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Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse Source 
Pull RCU updates from Ingo Molnar:

 - Continued initialization/Kconfig updates: hide most Kconfig options
   from unsuspecting users.

   There's now a single high level configuration option:

        *
        * RCU Subsystem
        *
        Make expert-level adjustments to RCU configuration (RCU_EXPERT) [N/y/?] (NEW)

   Which if answered in the negative, leaves us with a single
   interactive configuration option:

        Offload RCU callback processing from boot-selected CPUs (RCU_NOCB_CPU) [N/y/?] (NEW)

   All the rest of the RCU options are configured automatically.  Later
   on we'll remove this single leftover configuration option as well.

 - Remove all uses of RCU-protected array indexes: replace the
   rcu_[access|dereference]_index_check() APIs with READ_ONCE() and
   rcu_lockdep_assert()

 - RCU CPU-hotplug cleanups

 - Updates to Tiny RCU: a race fix and further code shrinkage.

 - RCU torture-testing updates: fixes, speedups, cleanups and
   documentation updates.

 - Miscellaneous fixes

 - Documentation updates

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
  rcutorture: Allow repetition factors in Kconfig-fragment lists
  rcutorture: Display "make oldconfig" errors
  rcutorture: Update TREE_RCU-kconfig.txt
  rcutorture: Make rcutorture scripts force RCU_EXPERT
  rcutorture: Update configuration fragments for rcutree.rcu_fanout_exact
  rcutorture: TASKS_RCU set directly, so don't explicitly set it
  rcutorture: Test SRCU cleanup code path
  rcutorture: Replace barriers with smp_store_release() and smp_load_acquire()
  locktorture: Change longdelay_us to longdelay_ms
  rcutorture: Allow negative values of nreaders to oversubscribe
  rcutorture: Exchange TREE03 and TREE08 NR_CPUS, speed up CPU hotplug
  rcutorture: Exchange TREE03 and TREE04 geometries
  locktorture: fix deadlock in 'rw_lock_irq' type
  rcu: Correctly handle non-empty Tiny RCU callback list with none ready
  rcutorture: Test both RCU-sched and RCU-bh for Tiny RCU
  rcu: Further shrink Tiny RCU by making empty functions static inlines
  rcu: Conditionally compile RCU's eqs warnings
  rcu: Remove prompt for RCU implementation
  rcu: Make RCU able to tolerate undefined CONFIG_RCU_KTHREAD_PRIO
  rcu: Make RCU able to tolerate undefined CONFIG_RCU_FANOUT_LEAF
  ...
This commit is contained in:
Linus Torvalds
2015-06-22 14:01:01 -07:00
parent 052b398a43 085c789783
commit fc934d4017
57 changed files with 808 additions and 623 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/cpu.c
View File

@@ -398,7 +398,6 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
if (err) {
/* CPU didn't die: tell everyone. Can't complain. */
smpboot_unpark_threads(cpu);
cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
goto out_release;
}
@@ -463,6 +462,7 @@ static int smpboot_thread_call(struct notifier_block *nfb,
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_FAILED:
case CPU_ONLINE:
smpboot_unpark_threads(cpu);
break;
@@ -479,7 +479,7 @@ static struct notifier_block smpboot_thread_notifier = {
.priority = CPU_PRI_SMPBOOT,
};
void __cpuinit smpboot_thread_init(void)
void smpboot_thread_init(void)
{
register_cpu_notifier(&smpboot_thread_notifier);
}

2
kernel/events/ring_buffer.c
View File

@@ -141,7 +141,7 @@ int perf_output_begin(struct perf_output_handle *handle,
perf_output_get_handle(handle);
do {
tail = ACCESS_ONCE(rb->user_page->data_tail);
tail = READ_ONCE_CTRL(rb->user_page->data_tail);
offset = head = local_read(&rb->head);
if (!rb->overwrite &&
unlikely(CIRC_SPACE(head, tail, perf_data_size(rb)) < size))

14
kernel/locking/locktorture.c
View File

@@ -122,12 +122,12 @@ static int torture_lock_busted_write_lock(void)
static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
{
const unsigned long longdelay_us = 100;
const unsigned long longdelay_ms = 100;
/* We want a long delay occasionally to force massive contention. */
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2000 * longdelay_us)))
mdelay(longdelay_us);
(cxt.nrealwriters_stress * 2000 * longdelay_ms)))
mdelay(longdelay_ms);
#ifdef CONFIG_PREEMPT
if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
preempt_schedule(); /* Allow test to be preempted. */
@@ -160,14 +160,14 @@ static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
{
const unsigned long shortdelay_us = 2;
const unsigned long longdelay_us = 100;
const unsigned long longdelay_ms = 100;
/* We want a short delay mostly to emulate likely code, and
* we want a long delay occasionally to force massive contention.
*/
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2000 * longdelay_us)))
mdelay(longdelay_us);
(cxt.nrealwriters_stress * 2000 * longdelay_ms)))
mdelay(longdelay_ms);
if (!(torture_random(trsp) %
(cxt.nrealwriters_stress * 2 * shortdelay_us)))
udelay(shortdelay_us);
@@ -309,7 +309,7 @@ static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
static void torture_rwlock_read_unlock_irq(void)
__releases(torture_rwlock)
{
write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
read_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
}
static struct lock_torture_ops rw_lock_irq_ops = {

103
kernel/rcu/rcutorture.c
View File

@@ -241,6 +241,7 @@ rcu_torture_free(struct rcu_torture *p)
struct rcu_torture_ops {
int ttype;
void (*init)(void);
void (*cleanup)(void);
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *rrsp);
void (*readunlock)(int idx);
@@ -477,10 +478,12 @@ static struct rcu_torture_ops rcu_busted_ops = {
*/
DEFINE_STATIC_SRCU(srcu_ctl);
static struct srcu_struct srcu_ctld;
static struct srcu_struct *srcu_ctlp = &srcu_ctl;
static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
{
return srcu_read_lock(&srcu_ctl);
return srcu_read_lock(srcu_ctlp);
}
static void srcu_read_delay(struct torture_random_state *rrsp)
@@ -499,49 +502,49 @@ static void srcu_read_delay(struct torture_random_state *rrsp)
rcu_read_delay(rrsp);
}
static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
{
srcu_read_unlock(&srcu_ctl, idx);
srcu_read_unlock(srcu_ctlp, idx);
}
static unsigned long srcu_torture_completed(void)
{
return srcu_batches_completed(&srcu_ctl);
return srcu_batches_completed(srcu_ctlp);
}
static void srcu_torture_deferred_free(struct rcu_torture *rp)
{
call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
}
static void srcu_torture_synchronize(void)
{
synchronize_srcu(&srcu_ctl);
synchronize_srcu(srcu_ctlp);
}
static void srcu_torture_call(struct rcu_head *head,
void (*func)(struct rcu_head *head))
{
call_srcu(&srcu_ctl, head, func);
call_srcu(srcu_ctlp, head, func);
}
static void srcu_torture_barrier(void)
{
srcu_barrier(&srcu_ctl);
srcu_barrier(srcu_ctlp);
}
static void srcu_torture_stats(void)
{
int cpu;
int idx = srcu_ctl.completed & 0x1;
int idx = srcu_ctlp->completed & 0x1;
pr_alert("%s%s per-CPU(idx=%d):",
torture_type, TORTURE_FLAG, idx);
for_each_possible_cpu(cpu) {
long c0, c1;
c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
}
pr_cont("\n");
@@ -549,7 +552,7 @@ static void srcu_torture_stats(void)
static void srcu_torture_synchronize_expedited(void)
{
synchronize_srcu_expedited(&srcu_ctl);
synchronize_srcu_expedited(srcu_ctlp);
}
static struct rcu_torture_ops srcu_ops = {
@@ -569,6 +572,38 @@ static struct rcu_torture_ops srcu_ops = {
.name = "srcu"
};
static void srcu_torture_init(void)
{
rcu_sync_torture_init();
WARN_ON(init_srcu_struct(&srcu_ctld));
srcu_ctlp = &srcu_ctld;
}
static void srcu_torture_cleanup(void)
{
cleanup_srcu_struct(&srcu_ctld);
srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
}
/* As above, but dynamically allocated. */
static struct rcu_torture_ops srcud_ops = {
.ttype = SRCU_FLAVOR,
.init = srcu_torture_init,
.cleanup = srcu_torture_cleanup,
.readlock = srcu_torture_read_lock,
.read_delay = srcu_read_delay,
.readunlock = srcu_torture_read_unlock,
.started = NULL,
.completed = srcu_torture_completed,
.deferred_free = srcu_torture_deferred_free,
.sync = srcu_torture_synchronize,
.exp_sync = srcu_torture_synchronize_expedited,
.call = srcu_torture_call,
.cb_barrier = srcu_torture_barrier,
.stats = srcu_torture_stats,
.name = "srcud"
};
/*
* Definitions for sched torture testing.
*/
@@ -672,8 +707,8 @@ static void rcu_torture_boost_cb(struct rcu_head *head)
struct rcu_boost_inflight *rbip =
container_of(head, struct rcu_boost_inflight, rcu);
smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
rbip->inflight = 0;
/* Ensure RCU-core accesses precede clearing ->inflight */
smp_store_release(&rbip->inflight, 0);
}
static int rcu_torture_boost(void *arg)
@@ -710,9 +745,9 @@ static int rcu_torture_boost(void *arg)
call_rcu_time = jiffies;
while (ULONG_CMP_LT(jiffies, endtime)) {
/* If we don't have a callback in flight, post one. */
if (!rbi.inflight) {
smp_mb(); /* RCU core before ->inflight = 1. */
rbi.inflight = 1;
if (!smp_load_acquire(&rbi.inflight)) {
/* RCU core before ->inflight = 1. */
smp_store_release(&rbi.inflight, 1);
call_rcu(&rbi.rcu, rcu_torture_boost_cb);
if (jiffies - call_rcu_time >
test_boost_duration * HZ - HZ / 2) {
@@ -751,11 +786,10 @@ checkwait: stutter_wait("rcu_torture_boost");
} while (!torture_must_stop());
/* Clean up and exit. */
while (!kthread_should_stop() || rbi.inflight) {
while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
torture_shutdown_absorb("rcu_torture_boost");
schedule_timeout_uninterruptible(1);
}
smp_mb(); /* order accesses to ->inflight before stack-frame death. */
destroy_rcu_head_on_stack(&rbi.rcu);
torture_kthread_stopping("rcu_torture_boost");
return 0;
@@ -1054,7 +1088,7 @@ static void rcu_torture_timer(unsigned long unused)
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
srcu_read_lock_held(&srcu_ctl));
srcu_read_lock_held(srcu_ctlp));
if (p == NULL) {
/* Leave because rcu_torture_writer is not yet underway */
cur_ops->readunlock(idx);
@@ -1128,7 +1162,7 @@ rcu_torture_reader(void *arg)
p = rcu_dereference_check(rcu_torture_current,
rcu_read_lock_bh_held() ||
rcu_read_lock_sched_held() ||
srcu_read_lock_held(&srcu_ctl));
srcu_read_lock_held(srcu_ctlp));
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
cur_ops->readunlock(idx);
@@ -1413,12 +1447,15 @@ static int rcu_torture_barrier_cbs(void *arg)
do {
wait_event(barrier_cbs_wq[myid],
(newphase =
ACCESS_ONCE(barrier_phase)) != lastphase ||
smp_load_acquire(&barrier_phase)) != lastphase ||
torture_must_stop());
lastphase = newphase;
smp_mb(); /* ensure barrier_phase load before ->call(). */
if (torture_must_stop())
break;
/*
* The above smp_load_acquire() ensures barrier_phase load
* is ordered before the folloiwng ->call().
*/
cur_ops->call(&rcu, rcu_torture_barrier_cbf);
if (atomic_dec_and_test(&barrier_cbs_count))
wake_up(&barrier_wq);
@@ -1439,8 +1476,8 @@ static int rcu_torture_barrier(void *arg)
do {
atomic_set(&barrier_cbs_invoked, 0);
atomic_set(&barrier_cbs_count, n_barrier_cbs);
smp_mb(); /* Ensure barrier_phase after prior assignments. */
barrier_phase = !barrier_phase;
/* Ensure barrier_phase ordered after prior assignments. */
smp_store_release(&barrier_phase, !barrier_phase);
for (i = 0; i < n_barrier_cbs; i++)
wake_up(&barrier_cbs_wq[i]);
wait_event(barrier_wq,
@@ -1588,10 +1625,14 @@ rcu_torture_cleanup(void)
rcutorture_booster_cleanup(i);
}
/* Wait for all RCU callbacks to fire. */
/*
* Wait for all RCU callbacks to fire, then do flavor-specific
* cleanup operations.
*/
if (cur_ops->cb_barrier != NULL)
cur_ops->cb_barrier();
if (cur_ops->cleanup != NULL)
cur_ops->cleanup();
rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
@@ -1668,8 +1709,8 @@ rcu_torture_init(void)
int cpu;
int firsterr = 0;
static struct rcu_torture_ops *torture_ops[] = {
&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
RCUTORTURE_TASKS_OPS
&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
&sched_ops, RCUTORTURE_TASKS_OPS
};
if (!torture_init_begin(torture_type, verbose, &torture_runnable))
@@ -1701,7 +1742,7 @@ rcu_torture_init(void)
if (nreaders >= 0) {
nrealreaders = nreaders;
} else {
nrealreaders = num_online_cpus() - 1;
nrealreaders = num_online_cpus() - 2 - nreaders;
if (nrealreaders <= 0)
nrealreaders = 1;
}

10
kernel/rcu/srcu.c
View File

@@ -151,7 +151,7 @@ static unsigned long srcu_readers_seq_idx(struct srcu_struct *sp, int idx)
unsigned long t;
for_each_possible_cpu(cpu) {
t = ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->seq[idx]);
t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->seq[idx]);
sum += t;
}
return sum;
@@ -168,7 +168,7 @@ static unsigned long srcu_readers_active_idx(struct srcu_struct *sp, int idx)
unsigned long t;
for_each_possible_cpu(cpu) {
t = ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx]);
t = READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx]);
sum += t;
}
return sum;
@@ -265,8 +265,8 @@ static int srcu_readers_active(struct srcu_struct *sp)
unsigned long sum = 0;
for_each_possible_cpu(cpu) {
sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]);
sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]);
sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]);
sum += READ_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]);
}
return sum;
}
@@ -296,7 +296,7 @@ int __srcu_read_lock(struct srcu_struct *sp)
{
int idx;
idx = ACCESS_ONCE(sp->completed) & 0x1;
idx = READ_ONCE(sp->completed) & 0x1;
preempt_disable();
__this_cpu_inc(sp->per_cpu_ref->c[idx]);
smp_mb(); /* B */ /* Avoid leaking the critical section. */

38
kernel/rcu/tiny.c
View File

@@ -49,39 +49,6 @@ static void __call_rcu(struct rcu_head *head,
#include "tiny_plugin.h"
/*
* Enter idle, which is an extended quiescent state if we have fully
* entered that mode.
*/
void rcu_idle_enter(void)
{
}
EXPORT_SYMBOL_GPL(rcu_idle_enter);
/*
* Exit an interrupt handler towards idle.
*/
void rcu_irq_exit(void)
{
}
EXPORT_SYMBOL_GPL(rcu_irq_exit);
/*
* Exit idle, so that we are no longer in an extended quiescent state.
*/
void rcu_idle_exit(void)
{
}
EXPORT_SYMBOL_GPL(rcu_idle_exit);
/*
* Enter an interrupt handler, moving away from idle.
*/
void rcu_irq_enter(void)
{
}
EXPORT_SYMBOL_GPL(rcu_irq_enter);
#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE)
/*
@@ -170,6 +137,11 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp)
/* Move the ready-to-invoke callbacks to a local list. */
local_irq_save(flags);
if (rcp->donetail == &rcp->rcucblist) {
/* No callbacks ready, so just leave. */
local_irq_restore(flags);
return;
}
RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, rcp->qlen, -1));
list = rcp->rcucblist;
rcp->rcucblist = *rcp->donetail;

12
kernel/rcu/tiny_plugin.h
View File

@@ -144,16 +144,17 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp)
return;
rcp->ticks_this_gp++;
j = jiffies;
js = ACCESS_ONCE(rcp->jiffies_stall);
js = READ_ONCE(rcp->jiffies_stall);
if (rcp->rcucblist && ULONG_CMP_GE(j, js)) {
pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
rcp->name, rcp->ticks_this_gp, DYNTICK_TASK_EXIT_IDLE,
jiffies - rcp->gp_start, rcp->qlen);
dump_stack();
ACCESS_ONCE(rcp->jiffies_stall) = jiffies +
3 * rcu_jiffies_till_stall_check() + 3;
WRITE_ONCE(rcp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
} else if (ULONG_CMP_GE(j, js)) {
ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check();
WRITE_ONCE(rcp->jiffies_stall,
jiffies + rcu_jiffies_till_stall_check());
}
}
@@ -161,7 +162,8 @@ static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
{
rcp->ticks_this_gp = 0;
rcp->gp_start = jiffies;
ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check();
WRITE_ONCE(rcp->jiffies_stall,
jiffies + rcu_jiffies_till_stall_check());
}
static void check_cpu_stalls(void)

365
kernel/rcu/tree.c
View File

@@ -91,7 +91,7 @@ static const char *tp_##sname##_varname __used __tracepoint_string = sname##_var
#define RCU_STATE_INITIALIZER(sname, sabbr, cr) \
DEFINE_RCU_TPS(sname) \
DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, sname##_data); \
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, sname##_data); \
struct rcu_state sname##_state = { \
.level = { &sname##_state.node[0] }, \
.rda = &sname##_data, \
@@ -110,11 +110,18 @@ struct rcu_state sname##_state = { \
RCU_STATE_INITIALIZER(rcu_sched, 's', call_rcu_sched);
RCU_STATE_INITIALIZER(rcu_bh, 'b', call_rcu_bh);
static struct rcu_state *rcu_state_p;
static struct rcu_state *const rcu_state_p;
static struct rcu_data __percpu *const rcu_data_p;
LIST_HEAD(rcu_struct_flavors);
/* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */
static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF;
/* Dump rcu_node combining tree at boot to verify correct setup. */
static bool dump_tree;
module_param(dump_tree, bool, 0444);
/* Control rcu_node-tree auto-balancing at boot time. */
static bool rcu_fanout_exact;
module_param(rcu_fanout_exact, bool, 0444);
/* Increase (but not decrease) the RCU_FANOUT_LEAF at boot time. */
static int rcu_fanout_leaf = RCU_FANOUT_LEAF;
module_param(rcu_fanout_leaf, int, 0444);
int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
static int num_rcu_lvl[] = { /* Number of rcu_nodes at specified level. */
@@ -159,17 +166,46 @@ static void invoke_rcu_core(void);
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
/* rcuc/rcub kthread realtime priority */
#ifdef CONFIG_RCU_KTHREAD_PRIO
static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO;
#else /* #ifdef CONFIG_RCU_KTHREAD_PRIO */
static int kthread_prio = IS_ENABLED(CONFIG_RCU_BOOST) ? 1 : 0;
#endif /* #else #ifdef CONFIG_RCU_KTHREAD_PRIO */
module_param(kthread_prio, int, 0644);
/* Delay in jiffies for grace-period initialization delays, debug only. */
#ifdef CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT
static int gp_preinit_delay = CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT_DELAY;
module_param(gp_preinit_delay, int, 0644);
#else /* #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT */
static const int gp_preinit_delay;
#endif /* #else #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT */
#ifdef CONFIG_RCU_TORTURE_TEST_SLOW_INIT
static int gp_init_delay = CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY;
module_param(gp_init_delay, int, 0644);
#else /* #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_INIT */
static const int gp_init_delay;
#endif /* #else #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_INIT */
#define PER_RCU_NODE_PERIOD 10 /* Number of grace periods between delays. */
#ifdef CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP
static int gp_cleanup_delay = CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY;
module_param(gp_cleanup_delay, int, 0644);
#else /* #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP */
static const int gp_cleanup_delay;
#endif /* #else #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP */
/*
* Number of grace periods between delays, normalized by the duration of
* the delay. The longer the the delay, the more the grace periods between
* each delay. The reason for this normalization is that it means that,
* for non-zero delays, the overall slowdown of grace periods is constant
* regardless of the duration of the delay. This arrangement balances
* the need for long delays to increase some race probabilities with the
* need for fast grace periods to increase other race probabilities.
*/
#define PER_RCU_NODE_PERIOD 3 /* Number of grace periods between delays. */
/*
* Track the rcutorture test sequence number and the update version
@@ -191,17 +227,17 @@ unsigned long rcutorture_vernum;
*/
unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
{
return ACCESS_ONCE(rnp->qsmaskinitnext);
return READ_ONCE(rnp->qsmaskinitnext);
}
/*
* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
* Return true if an RCU grace period is in progress. The READ_ONCE()s
* permit this function to be invoked without holding the root rcu_node
* structure's ->lock, but of course results can be subject to change.
*/
static int rcu_gp_in_progress(struct rcu_state *rsp)
{
return ACCESS_ONCE(rsp->completed) != ACCESS_ONCE(rsp->gpnum);
return READ_ONCE(rsp->completed) != READ_ONCE(rsp->gpnum);
}
/*
@@ -278,8 +314,8 @@ static void rcu_momentary_dyntick_idle(void)
if (!(resched_mask & rsp->flavor_mask))
continue;
smp_mb(); /* rcu_sched_qs_mask before cond_resched_completed. */
if (ACCESS_ONCE(rdp->mynode->completed) !=
ACCESS_ONCE(rdp->cond_resched_completed))
if (READ_ONCE(rdp->mynode->completed) !=
READ_ONCE(rdp->cond_resched_completed))
continue;
/*
@@ -491,9 +527,9 @@ void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
break;
}
if (rsp != NULL) {
*flags = ACCESS_ONCE(rsp->gp_flags);
*gpnum = ACCESS_ONCE(rsp->gpnum);
*completed = ACCESS_ONCE(rsp->completed);
*flags = READ_ONCE(rsp->gp_flags);
*gpnum = READ_ONCE(rsp->gpnum);
*completed = READ_ONCE(rsp->completed);
return;
}
*flags = 0;
@@ -539,10 +575,10 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp)
static int rcu_future_needs_gp(struct rcu_state *rsp)
{
struct rcu_node *rnp = rcu_get_root(rsp);
int idx = (ACCESS_ONCE(rnp->completed) + 1) & 0x1;
int idx = (READ_ONCE(rnp->completed) + 1) & 0x1;
int *fp = &rnp->need_future_gp[idx];
return ACCESS_ONCE(*fp);
return READ_ONCE(*fp);
}
/*
@@ -565,7 +601,7 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
return 1; /* Yes, this CPU has newly registered callbacks. */
for (i = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++)
if (rdp->nxttail[i - 1] != rdp->nxttail[i] &&
ULONG_CMP_LT(ACCESS_ONCE(rsp->completed),
ULONG_CMP_LT(READ_ONCE(rsp->completed),
rdp->nxtcompleted[i]))
return 1; /* Yes, CBs for future grace period. */
return 0; /* No grace period needed. */
@@ -585,7 +621,8 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
if (!user && !is_idle_task(current)) {
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!user && !is_idle_task(current)) {
struct task_struct *idle __maybe_unused =
idle_task(smp_processor_id());
@@ -604,7 +641,8 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
smp_mb__before_atomic(); /* See above. */
atomic_inc(&rdtp->dynticks);
smp_mb__after_atomic(); /* Force ordering with next sojourn. */
WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
atomic_read(&rdtp->dynticks) & 0x1);
rcu_dynticks_task_enter();
/*
@@ -630,7 +668,8 @@ static void rcu_eqs_enter(bool user)
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
WARN_ON_ONCE((oldval & DYNTICK_TASK_NEST_MASK) == 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
(oldval & DYNTICK_TASK_NEST_MASK) == 0);
if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
rdtp->dynticks_nesting = 0;
rcu_eqs_enter_common(oldval, user);
@@ -703,7 +742,8 @@ void rcu_irq_exit(void)
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
rdtp->dynticks_nesting--;
WARN_ON_ONCE(rdtp->dynticks_nesting < 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
rdtp->dynticks_nesting < 0);
if (rdtp->dynticks_nesting)
trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting);
else
@@ -728,10 +768,12 @@ static void rcu_eqs_exit_common(long long oldval, int user)
atomic_inc(&rdtp->dynticks);
/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
smp_mb__after_atomic(); /* See above. */
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!(atomic_read(&rdtp->dynticks) & 0x1));
rcu_cleanup_after_idle();
trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting);
if (!user && !is_idle_task(current)) {
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!user && !is_idle_task(current)) {
struct task_struct *idle __maybe_unused =
idle_task(smp_processor_id());
@@ -755,7 +797,7 @@ static void rcu_eqs_exit(bool user)
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
WARN_ON_ONCE(oldval < 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
if (oldval & DYNTICK_TASK_NEST_MASK) {
rdtp->dynticks_nesting += DYNTICK_TASK_NEST_VALUE;
} else {
@@ -828,7 +870,8 @@ void rcu_irq_enter(void)
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
rdtp->dynticks_nesting++;
WARN_ON_ONCE(rdtp->dynticks_nesting == 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
rdtp->dynticks_nesting == 0);
if (oldval)
trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting);
else
@@ -1011,9 +1054,9 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp,
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
return 1;
} else {
if (ULONG_CMP_LT(ACCESS_ONCE(rdp->gpnum) + ULONG_MAX / 4,
if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
rdp->mynode->gpnum))
ACCESS_ONCE(rdp->gpwrap) = true;
WRITE_ONCE(rdp->gpwrap, true);
return 0;
}
}
@@ -1093,12 +1136,12 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
if (ULONG_CMP_GE(jiffies,
rdp->rsp->gp_start + jiffies_till_sched_qs) ||
ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) {
if (!(ACCESS_ONCE(*rcrmp) & rdp->rsp->flavor_mask)) {
ACCESS_ONCE(rdp->cond_resched_completed) =
ACCESS_ONCE(rdp->mynode->completed);
if (!(READ_ONCE(*rcrmp) & rdp->rsp->flavor_mask)) {
WRITE_ONCE(rdp->cond_resched_completed,
READ_ONCE(rdp->mynode->completed));
smp_mb(); /* ->cond_resched_completed before *rcrmp. */
ACCESS_ONCE(*rcrmp) =
ACCESS_ONCE(*rcrmp) + rdp->rsp->flavor_mask;
WRITE_ONCE(*rcrmp,
READ_ONCE(*rcrmp) + rdp->rsp->flavor_mask);
resched_cpu(rdp->cpu); /* Force CPU into scheduler. */
rdp->rsp->jiffies_resched += 5; /* Enable beating. */
} else if (ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) {
@@ -1119,9 +1162,9 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
rsp->gp_start = j;
smp_wmb(); /* Record start time before stall time. */
j1 = rcu_jiffies_till_stall_check();
ACCESS_ONCE(rsp->jiffies_stall) = j + j1;
WRITE_ONCE(rsp->jiffies_stall, j + j1);
rsp->jiffies_resched = j + j1 / 2;
rsp->n_force_qs_gpstart = ACCESS_ONCE(rsp->n_force_qs);
rsp->n_force_qs_gpstart = READ_ONCE(rsp->n_force_qs);
}
/*
@@ -1133,10 +1176,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
unsigned long j;
j = jiffies;
gpa = ACCESS_ONCE(rsp->gp_activity);
gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ)
pr_err("%s kthread starved for %ld jiffies!\n",
rsp->name, j - gpa);
pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x\n",
rsp->name, j - gpa,
rsp->gpnum, rsp->completed, rsp->gp_flags);
}
/*
@@ -1173,12 +1217,13 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
/* Only let one CPU complain about others per time interval. */
raw_spin_lock_irqsave(&rnp->lock, flags);
delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall);
delta = jiffies - READ_ONCE(rsp->jiffies_stall);
if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
ACCESS_ONCE(rsp->jiffies_stall) = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
WRITE_ONCE(rsp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
/*
@@ -1212,12 +1257,12 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
if (ndetected) {
rcu_dump_cpu_stacks(rsp);
} else {
if (ACCESS_ONCE(rsp->gpnum) != gpnum ||
ACCESS_ONCE(rsp->completed) == gpnum) {
if (READ_ONCE(rsp->gpnum) != gpnum ||
READ_ONCE(rsp->completed) == gpnum) {
pr_err("INFO: Stall ended before state dump start\n");
} else {
j = jiffies;
gpa = ACCESS_ONCE(rsp->gp_activity);
gpa = READ_ONCE(rsp->gp_activity);
pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n",
rsp->name, j - gpa, j, gpa,
jiffies_till_next_fqs,
@@ -1262,9 +1307,9 @@ static void print_cpu_stall(struct rcu_state *rsp)
rcu_dump_cpu_stacks(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
if (ULONG_CMP_GE(jiffies, ACCESS_ONCE(rsp->jiffies_stall)))
ACCESS_ONCE(rsp->jiffies_stall) = jiffies +
3 * rcu_jiffies_till_stall_check() + 3;
if (ULONG_CMP_GE(jiffies, READ_ONCE(rsp->jiffies_stall)))
WRITE_ONCE(rsp->jiffies_stall,
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
/*
@@ -1307,20 +1352,20 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
* Given this check, comparisons of jiffies, rsp->jiffies_stall,
* and rsp->gp_start suffice to forestall false positives.
*/
gpnum = ACCESS_ONCE(rsp->gpnum);
gpnum = READ_ONCE(rsp->gpnum);
smp_rmb(); /* Pick up ->gpnum first... */
js = ACCESS_ONCE(rsp->jiffies_stall);
js = READ_ONCE(rsp->jiffies_stall);
smp_rmb(); /* ...then ->jiffies_stall before the rest... */
gps = ACCESS_ONCE(rsp->gp_start);
gps = READ_ONCE(rsp->gp_start);
smp_rmb(); /* ...and finally ->gp_start before ->completed. */
completed = ACCESS_ONCE(rsp->completed);
completed = READ_ONCE(rsp->completed);
if (ULONG_CMP_GE(completed, gpnum) ||
ULONG_CMP_LT(j, js) ||
ULONG_CMP_GE(gps, js))
return; /* No stall or GP completed since entering function. */
rnp = rdp->mynode;
if (rcu_gp_in_progress(rsp) &&
(ACCESS_ONCE(rnp->qsmask) & rdp->grpmask)) {
(READ_ONCE(rnp->qsmask) & rdp->grpmask)) {
/* We haven't checked in, so go dump stack. */
print_cpu_stall(rsp);
@@ -1347,7 +1392,7 @@ void rcu_cpu_stall_reset(void)
struct rcu_state *rsp;
for_each_rcu_flavor(rsp)
ACCESS_ONCE(rsp->jiffies_stall) = jiffies + ULONG_MAX / 2;
WRITE_ONCE(rsp->jiffies_stall, jiffies + ULONG_MAX / 2);
}
/*
@@ -1457,7 +1502,7 @@ rcu_start_future_gp(struct rcu_node *rnp, struct rcu_data *rdp,
* doing some extra useless work.
*/
if (rnp->gpnum != rnp->completed ||
ACCESS_ONCE(rnp_root->gpnum) != ACCESS_ONCE(rnp_root->completed)) {
READ_ONCE(rnp_root->gpnum) != READ_ONCE(rnp_root->completed)) {
rnp->need_future_gp[c & 0x1]++;
trace_rcu_future_gp(rnp, rdp, c, TPS("Startedleaf"));
goto out;
@@ -1542,7 +1587,7 @@ static int rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
static void rcu_gp_kthread_wake(struct rcu_state *rsp)
{
if (current == rsp->gp_kthread ||
!ACCESS_ONCE(rsp->gp_flags) ||
!READ_ONCE(rsp->gp_flags) ||
!rsp->gp_kthread)
return;
wake_up(&rsp->gp_wq);
@@ -1677,7 +1722,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
/* Handle the ends of any preceding grace periods first. */
if (rdp->completed == rnp->completed &&
!unlikely(ACCESS_ONCE(rdp->gpwrap))) {
!unlikely(READ_ONCE(rdp->gpwrap))) {
/* No grace period end, so just accelerate recent callbacks. */
ret = rcu_accelerate_cbs(rsp, rnp, rdp);
@@ -1692,7 +1737,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuend"));
}
if (rdp->gpnum != rnp->gpnum || unlikely(ACCESS_ONCE(rdp->gpwrap))) {
if (rdp->gpnum != rnp->gpnum || unlikely(READ_ONCE(rdp->gpwrap))) {
/*
* If the current grace period is waiting for this CPU,
* set up to detect a quiescent state, otherwise don't
@@ -1704,7 +1749,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
rdp->qs_pending = !!(rnp->qsmask & rdp->grpmask);
zero_cpu_stall_ticks(rdp);
ACCESS_ONCE(rdp->gpwrap) = false;
WRITE_ONCE(rdp->gpwrap, false);
}
return ret;
}
@@ -1717,9 +1762,9 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
local_irq_save(flags);
rnp = rdp->mynode;
if ((rdp->gpnum == ACCESS_ONCE(rnp->gpnum) &&
rdp->completed == ACCESS_ONCE(rnp->completed) &&
!unlikely(ACCESS_ONCE(rdp->gpwrap))) || /* w/out lock. */
if ((rdp->gpnum == READ_ONCE(rnp->gpnum) &&
rdp->completed == READ_ONCE(rnp->completed) &&
!unlikely(READ_ONCE(rdp->gpwrap))) || /* w/out lock. */
!raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
local_irq_restore(flags);
return;
@@ -1731,6 +1776,13 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
rcu_gp_kthread_wake(rsp);
}
static void rcu_gp_slow(struct rcu_state *rsp, int delay)
{
if (delay > 0 &&
!(rsp->gpnum % (rcu_num_nodes * PER_RCU_NODE_PERIOD * delay)))
schedule_timeout_uninterruptible(delay);
}
/*
* Initialize a new grace period. Return 0 if no grace period required.
*/
@@ -1740,15 +1792,15 @@ static int rcu_gp_init(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
if (!ACCESS_ONCE(rsp->gp_flags)) {
if (!READ_ONCE(rsp->gp_flags)) {
/* Spurious wakeup, tell caller to go back to sleep. */
raw_spin_unlock_irq(&rnp->lock);
return 0;
}
ACCESS_ONCE(rsp->gp_flags) = 0; /* Clear all flags: New grace period. */
WRITE_ONCE(rsp->gp_flags, 0); /* Clear all flags: New grace period. */
if (WARN_ON_ONCE(rcu_gp_in_progress(rsp))) {
/*
@@ -1773,6 +1825,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
* will handle subsequent offline CPUs.
*/
rcu_for_each_leaf_node(rsp, rnp) {
rcu_gp_slow(rsp, gp_preinit_delay);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
if (rnp->qsmaskinit == rnp->qsmaskinitnext &&
@@ -1829,14 +1882,15 @@ static int rcu_gp_init(struct rcu_state *rsp)
* process finishes, because this kthread handles both.
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
rcu_gp_slow(rsp, gp_init_delay);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
rdp = this_cpu_ptr(rsp->rda);
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
ACCESS_ONCE(rnp->gpnum) = rsp->gpnum;
WRITE_ONCE(rnp->gpnum, rsp->gpnum);
if (WARN_ON_ONCE(rnp->completed != rsp->completed))
ACCESS_ONCE(rnp->completed) = rsp->completed;
WRITE_ONCE(rnp->completed, rsp->completed);
if (rnp == rdp->mynode)
(void)__note_gp_changes(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp);
@@ -1845,10 +1899,7 @@ static int rcu_gp_init(struct rcu_state *rsp)
rnp->grphi, rnp->qsmask);
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
ACCESS_ONCE(rsp->gp_activity) = jiffies;
if (gp_init_delay > 0 &&
!(rsp->gpnum % (rcu_num_nodes * PER_RCU_NODE_PERIOD)))
schedule_timeout_uninterruptible(gp_init_delay);
WRITE_ONCE(rsp->gp_activity, jiffies);
}
return 1;
@@ -1864,7 +1915,7 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
unsigned long maxj;
struct rcu_node *rnp = rcu_get_root(rsp);
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
rsp->n_force_qs++;
if (fqs_state == RCU_SAVE_DYNTICK) {
/* Collect dyntick-idle snapshots. */
@@ -1882,11 +1933,11 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
}
/* Clear flag to prevent immediate re-entry. */
if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
ACCESS_ONCE(rsp->gp_flags) =
ACCESS_ONCE(rsp->gp_flags) & ~RCU_GP_FLAG_FQS;
WRITE_ONCE(rsp->gp_flags,
READ_ONCE(rsp->gp_flags) & ~RCU_GP_FLAG_FQS);
raw_spin_unlock_irq(&rnp->lock);
}
return fqs_state;
@@ -1903,7 +1954,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
gp_duration = jiffies - rsp->gp_start;
@@ -1934,7 +1985,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
smp_mb__after_unlock_lock();
WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
WARN_ON_ONCE(rnp->qsmask);
ACCESS_ONCE(rnp->completed) = rsp->gpnum;
WRITE_ONCE(rnp->completed, rsp->gpnum);
rdp = this_cpu_ptr(rsp->rda);
if (rnp == rdp->mynode)
needgp = __note_gp_changes(rsp, rnp, rdp) || needgp;
@@ -1942,7 +1993,8 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
nocb += rcu_future_gp_cleanup(rsp, rnp);
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
rcu_gp_slow(rsp, gp_cleanup_delay);
}
rnp = rcu_get_root(rsp);
raw_spin_lock_irq(&rnp->lock);
@@ -1950,16 +2002,16 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rcu_nocb_gp_set(rnp, nocb);
/* Declare grace period done. */
ACCESS_ONCE(rsp->completed) = rsp->gpnum;
WRITE_ONCE(rsp->completed, rsp->gpnum);
trace_rcu_grace_period(rsp->name, rsp->completed, TPS("end"));
rsp->fqs_state = RCU_GP_IDLE;
rdp = this_cpu_ptr(rsp->rda);
/* Advance CBs to reduce false positives below. */
needgp = rcu_advance_cbs(rsp, rnp, rdp) || needgp;
if (needgp || cpu_needs_another_gp(rsp, rdp)) {
ACCESS_ONCE(rsp->gp_flags) = RCU_GP_FLAG_INIT;
WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("newreq"));
}
raw_spin_unlock_irq(&rnp->lock);
@@ -1983,20 +2035,20 @@ static int __noreturn rcu_gp_kthread(void *arg)
/* Handle grace-period start. */
for (;;) {
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("reqwait"));
rsp->gp_state = RCU_GP_WAIT_GPS;
wait_event_interruptible(rsp->gp_wq,
ACCESS_ONCE(rsp->gp_flags) &
READ_ONCE(rsp->gp_flags) &
RCU_GP_FLAG_INIT);
/* Locking provides needed memory barrier. */
if (rcu_gp_init(rsp))
break;
cond_resched_rcu_qs();
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("reqwaitsig"));
}
@@ -2012,39 +2064,39 @@ static int __noreturn rcu_gp_kthread(void *arg)
if (!ret)
rsp->jiffies_force_qs = jiffies + j;
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("fqswait"));
rsp->gp_state = RCU_GP_WAIT_FQS;
ret = wait_event_interruptible_timeout(rsp->gp_wq,
((gf = ACCESS_ONCE(rsp->gp_flags)) &
((gf = READ_ONCE(rsp->gp_flags)) &
RCU_GP_FLAG_FQS) ||
(!ACCESS_ONCE(rnp->qsmask) &&
(!READ_ONCE(rnp->qsmask) &&
!rcu_preempt_blocked_readers_cgp(rnp)),
j);
/* Locking provides needed memory barriers. */
/* If grace period done, leave loop. */
if (!ACCESS_ONCE(rnp->qsmask) &&
if (!READ_ONCE(rnp->qsmask) &&
!rcu_preempt_blocked_readers_cgp(rnp))
break;
/* If time for quiescent-state forcing, do it. */
if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) ||
(gf & RCU_GP_FLAG_FQS)) {
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("fqsstart"));
fqs_state = rcu_gp_fqs(rsp, fqs_state);
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("fqsend"));
cond_resched_rcu_qs();
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
} else {
/* Deal with stray signal. */
cond_resched_rcu_qs();
ACCESS_ONCE(rsp->gp_activity) = jiffies;
WRITE_ONCE(rsp->gp_activity, jiffies);
WARN_ON(signal_pending(current));
trace_rcu_grace_period(rsp->name,
ACCESS_ONCE(rsp->gpnum),
READ_ONCE(rsp->gpnum),
TPS("fqswaitsig"));
}
j = jiffies_till_next_fqs;
@@ -2086,8 +2138,8 @@ rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
*/
return false;
}
ACCESS_ONCE(rsp->gp_flags) = RCU_GP_FLAG_INIT;
trace_rcu_grace_period(rsp->name, ACCESS_ONCE(rsp->gpnum),
WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
TPS("newreq"));
/*
@@ -2137,6 +2189,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
__releases(rcu_get_root(rsp)->lock)
{
WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
rcu_gp_kthread_wake(rsp);
}
@@ -2334,8 +2387,6 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
rcu_report_qs_rdp(rdp->cpu, rsp, rdp);
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* Send the specified CPU's RCU callbacks to the orphanage. The
* specified CPU must be offline, and the caller must hold the
@@ -2346,7 +2397,7 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
struct rcu_node *rnp, struct rcu_data *rdp)
{
/* No-CBs CPUs do not have orphanable callbacks. */
if (rcu_is_nocb_cpu(rdp->cpu))
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) || rcu_is_nocb_cpu(rdp->cpu))
return;
/*
@@ -2359,7 +2410,7 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
rsp->qlen += rdp->qlen;
rdp->n_cbs_orphaned += rdp->qlen;
rdp->qlen_lazy = 0;
ACCESS_ONCE(rdp->qlen) = 0;
WRITE_ONCE(rdp->qlen, 0);
}
/*
@@ -2405,7 +2456,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
struct rcu_data *rdp = raw_cpu_ptr(rsp->rda);
/* No-CBs CPUs are handled specially. */
if (rcu_nocb_adopt_orphan_cbs(rsp, rdp, flags))
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||
rcu_nocb_adopt_orphan_cbs(rsp, rdp, flags))
return;
/* Do the accounting first. */
@@ -2452,6 +2504,9 @@ static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
RCU_TRACE(struct rcu_data *rdp = this_cpu_ptr(rsp->rda));
RCU_TRACE(struct rcu_node *rnp = rdp->mynode);
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
return;
RCU_TRACE(mask = rdp->grpmask);
trace_rcu_grace_period(rsp->name,
rnp->gpnum + 1 - !!(rnp->qsmask & mask),
@@ -2480,7 +2535,8 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
long mask;
struct rcu_node *rnp = rnp_leaf;
if (rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU) ||
rnp->qsmaskinit || rcu_preempt_has_tasks(rnp))
return;
for (;;) {
mask = rnp->grpmask;
@@ -2511,6 +2567,9 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
return;
/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
mask = rdp->grpmask;
raw_spin_lock_irqsave(&rnp->lock, flags);
@@ -2532,6 +2591,9 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
return;
/* Adjust any no-longer-needed kthreads. */
rcu_boost_kthread_setaffinity(rnp, -1);
@@ -2546,26 +2608,6 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
cpu, rdp->qlen, rdp->nxtlist);
}
#else /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_cleanup_dying_cpu(struct rcu_state *rsp)
{
}
static void __maybe_unused rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
{
}
static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
{
}
static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
{
}
#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
/*
* Invoke any RCU callbacks that have made it to the end of their grace
* period. Thottle as specified by rdp->blimit.
@@ -2580,7 +2622,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
/* If no callbacks are ready, just return. */
if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
trace_rcu_batch_start(rsp->name, rdp->qlen_lazy, rdp->qlen, 0);
trace_rcu_batch_end(rsp->name, 0, !!ACCESS_ONCE(rdp->nxtlist),
trace_rcu_batch_end(rsp->name, 0, !!READ_ONCE(rdp->nxtlist),
need_resched(), is_idle_task(current),
rcu_is_callbacks_kthread());
return;
@@ -2636,7 +2678,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
}
smp_mb(); /* List handling before counting for rcu_barrier(). */
rdp->qlen_lazy -= count_lazy;
ACCESS_ONCE(rdp->qlen) = rdp->qlen - count;
WRITE_ONCE(rdp->qlen, rdp->qlen - count);
rdp->n_cbs_invoked += count;
/* Reinstate batch limit if we have worked down the excess. */
@@ -2730,10 +2772,6 @@ static void force_qs_rnp(struct rcu_state *rsp,
mask = 0;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
if (!rcu_gp_in_progress(rsp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
if (rnp->qsmask == 0) {
if (rcu_state_p == &rcu_sched_state ||
rsp != rcu_state_p ||
@@ -2763,8 +2801,6 @@ static void force_qs_rnp(struct rcu_state *rsp,
bit = 1;
for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
if ((rnp->qsmask & bit) != 0) {
if ((rnp->qsmaskinit & bit) == 0)
*isidle = false; /* Pending hotplug. */
if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
mask |= bit;
}
@@ -2793,7 +2829,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
/* Funnel through hierarchy to reduce memory contention. */
rnp = __this_cpu_read(rsp->rda->mynode);
for (; rnp != NULL; rnp = rnp->parent) {
ret = (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
ret = (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) ||
!raw_spin_trylock(&rnp->fqslock);
if (rnp_old != NULL)
raw_spin_unlock(&rnp_old->fqslock);
@@ -2809,13 +2845,12 @@ static void force_quiescent_state(struct rcu_state *rsp)
raw_spin_lock_irqsave(&rnp_old->lock, flags);
smp_mb__after_unlock_lock();
raw_spin_unlock(&rnp_old->fqslock);
if (ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
if (READ_ONCE(rsp->gp_flags) & RCU_GP_FLAG_FQS) {
rsp->n_force_qs_lh++;
raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
return; /* Someone beat us to it. */
}
ACCESS_ONCE(rsp->gp_flags) =
ACCESS_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS;
WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
rcu_gp_kthread_wake(rsp);
}
@@ -2881,7 +2916,7 @@ static void rcu_process_callbacks(struct softirq_action *unused)
*/
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
{
if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active)))
if (unlikely(!READ_ONCE(rcu_scheduler_fully_active)))
return;
if (likely(!rsp->boost)) {
rcu_do_batch(rsp, rdp);
@@ -2972,7 +3007,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
WARN_ON_ONCE((unsigned long)head & 0x1); /* Misaligned rcu_head! */
if (debug_rcu_head_queue(head)) {
/* Probable double call_rcu(), so leak the callback. */
ACCESS_ONCE(head->func) = rcu_leak_callback;
WRITE_ONCE(head->func, rcu_leak_callback);
WARN_ONCE(1, "__call_rcu(): Leaked duplicate callback\n");
return;
}
@@ -3011,7 +3046,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
if (!likely(rdp->nxtlist))
init_default_callback_list(rdp);
}
ACCESS_ONCE(rdp->qlen) = rdp->qlen + 1;
WRITE_ONCE(rdp->qlen, rdp->qlen + 1);
if (lazy)
rdp->qlen_lazy++;
else
@@ -3287,7 +3322,7 @@ void synchronize_sched_expedited(void)
if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start),
(ulong)atomic_long_read(&rsp->expedited_done) +
ULONG_MAX / 8)) {
synchronize_sched();
wait_rcu_gp(call_rcu_sched);
atomic_long_inc(&rsp->expedited_wrap);
return;
}
@@ -3450,14 +3485,14 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
}
/* Has another RCU grace period completed? */
if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
if (READ_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
rdp->n_rp_gp_completed++;
return 1;
}
/* Has a new RCU grace period started? */
if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum ||
unlikely(ACCESS_ONCE(rdp->gpwrap))) { /* outside lock */
if (READ_ONCE(rnp->gpnum) != rdp->gpnum ||
unlikely(READ_ONCE(rdp->gpwrap))) { /* outside lock */
rdp->n_rp_gp_started++;
return 1;
}
@@ -3493,7 +3528,7 @@ static int rcu_pending(void)
* non-NULL, store an indication of whether all callbacks are lazy.
* (If there are no callbacks, all of them are deemed to be lazy.)
*/
static int __maybe_unused rcu_cpu_has_callbacks(bool *all_lazy)
static bool __maybe_unused rcu_cpu_has_callbacks(bool *all_lazy)
{
bool al = true;
bool hc = false;
@@ -3564,7 +3599,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
{
int cpu;
struct rcu_data *rdp;
unsigned long snap = ACCESS_ONCE(rsp->n_barrier_done);
unsigned long snap = READ_ONCE(rsp->n_barrier_done);
unsigned long snap_done;
_rcu_barrier_trace(rsp, "Begin", -1, snap);
@@ -3606,10 +3641,10 @@ static void _rcu_barrier(struct rcu_state *rsp)
/*
* Increment ->n_barrier_done to avoid duplicate work. Use
* ACCESS_ONCE() to prevent the compiler from speculating
* WRITE_ONCE() to prevent the compiler from speculating
* the increment to precede the early-exit check.
*/
ACCESS_ONCE(rsp->n_barrier_done) = rsp->n_barrier_done + 1;
WRITE_ONCE(rsp->n_barrier_done, rsp->n_barrier_done + 1);
WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 1);
_rcu_barrier_trace(rsp, "Inc1", -1, rsp->n_barrier_done);
smp_mb(); /* Order ->n_barrier_done increment with below mechanism. */
@@ -3645,7 +3680,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
__call_rcu(&rdp->barrier_head,
rcu_barrier_callback, rsp, cpu, 0);
}
} else if (ACCESS_ONCE(rdp->qlen)) {
} else if (READ_ONCE(rdp->qlen)) {
_rcu_barrier_trace(rsp, "OnlineQ", cpu,
rsp->n_barrier_done);
smp_call_function_single(cpu, rcu_barrier_func, rsp, 1);
@@ -3665,7 +3700,7 @@ static void _rcu_barrier(struct rcu_state *rsp)
/* Increment ->n_barrier_done to prevent duplicate work. */
smp_mb(); /* Keep increment after above mechanism. */
ACCESS_ONCE(rsp->n_barrier_done) = rsp->n_barrier_done + 1;
WRITE_ONCE(rsp->n_barrier_done, rsp->n_barrier_done + 1);
WARN_ON_ONCE((rsp->n_barrier_done & 0x1) != 0);
_rcu_barrier_trace(rsp, "Inc2", -1, rsp->n_barrier_done);
smp_mb(); /* Keep increment before caller's subsequent code. */
@@ -3780,7 +3815,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->gpnum = rnp->completed; /* Make CPU later note any new GP. */
rdp->completed = rnp->completed;
rdp->passed_quiesce = false;
rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
rdp->rcu_qs_ctr_snap = per_cpu(rcu_qs_ctr, cpu);
rdp->qs_pending = false;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
raw_spin_unlock_irqrestore(&rnp->lock, flags);
@@ -3924,16 +3959,16 @@ void rcu_scheduler_starting(void)
/*
* Compute the per-level fanout, either using the exact fanout specified
* or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT.
* or balancing the tree, depending on the rcu_fanout_exact boot parameter.
*/
static void __init rcu_init_levelspread(struct rcu_state *rsp)
{
int i;
if (IS_ENABLED(CONFIG_RCU_FANOUT_EXACT)) {
if (rcu_fanout_exact) {
rsp->levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
for (i = rcu_num_lvls - 2; i >= 0; i--)
rsp->levelspread[i] = CONFIG_RCU_FANOUT;
rsp->levelspread[i] = RCU_FANOUT;
} else {
int ccur;
int cprv;
@@ -3971,9 +4006,9 @@ static void __init rcu_init_one(struct rcu_state *rsp,
BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
/* Silence gcc 4.8 warning about array index out of range. */
if (rcu_num_lvls > RCU_NUM_LVLS)
panic("rcu_init_one: rcu_num_lvls overflow");
/* Silence gcc 4.8 false positive about array index out of range. */
if (rcu_num_lvls <= 0 || rcu_num_lvls > RCU_NUM_LVLS)
panic("rcu_init_one: rcu_num_lvls out of range");
/* Initialize the level-tracking arrays. */
@@ -4059,7 +4094,7 @@ static void __init rcu_init_geometry(void)
jiffies_till_next_fqs = d;
/* If the compile-time values are accurate, just leave. */
if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF &&
if (rcu_fanout_leaf == RCU_FANOUT_LEAF &&
nr_cpu_ids == NR_CPUS)
return;
pr_info("RCU: Adjusting geometry for rcu_fanout_leaf=%d, nr_cpu_ids=%d\n",
@@ -4073,7 +4108,7 @@ static void __init rcu_init_geometry(void)
rcu_capacity[0] = 1;
rcu_capacity[1] = rcu_fanout_leaf;
for (i = 2; i <= MAX_RCU_LVLS; i++)
rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT;
rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT;
/*
* The boot-time rcu_fanout_leaf parameter is only permitted
@@ -4083,7 +4118,7 @@ static void __init rcu_init_geometry(void)
* the configured number of CPUs. Complain and fall back to the
* compile-time values if these limits are exceeded.
*/
if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF ||
if (rcu_fanout_leaf < RCU_FANOUT_LEAF ||
rcu_fanout_leaf > sizeof(unsigned long) * 8 ||
n > rcu_capacity[MAX_RCU_LVLS]) {
WARN_ON(1);
@@ -4109,6 +4144,28 @@ static void __init rcu_init_geometry(void)
rcu_num_nodes -= n;
}
/*
* Dump out the structure of the rcu_node combining tree associated
* with the rcu_state structure referenced by rsp.
*/
static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp)
{
int level = 0;
struct rcu_node *rnp;
pr_info("rcu_node tree layout dump\n");
pr_info(" ");
rcu_for_each_node_breadth_first(rsp, rnp) {
if (rnp->level != level) {
pr_cont("\n");
pr_info(" ");
level = rnp->level;
}
pr_cont("%d:%d ^%d ", rnp->grplo, rnp->grphi, rnp->grpnum);
}
pr_cont("\n");
}
void __init rcu_init(void)
{
int cpu;
@@ -4119,6 +4176,8 @@ void __init rcu_init(void)
rcu_init_geometry();
rcu_init_one(&rcu_bh_state, &rcu_bh_data);
rcu_init_one(&rcu_sched_state, &rcu_sched_data);
if (dump_tree)
rcu_dump_rcu_node_tree(&rcu_sched_state);
__rcu_init_preempt();
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);

35
kernel/rcu/tree.h
View File

@@ -35,11 +35,33 @@
* In practice, this did work well going from three levels to four.
* Of course, your mileage may vary.
*/
#define MAX_RCU_LVLS 4
#define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF)
#define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
#define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
#define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)
#ifdef CONFIG_RCU_FANOUT
#define RCU_FANOUT CONFIG_RCU_FANOUT
#else /* #ifdef CONFIG_RCU_FANOUT */
# ifdef CONFIG_64BIT
# define RCU_FANOUT 64
# else
# define RCU_FANOUT 32
# endif
#endif /* #else #ifdef CONFIG_RCU_FANOUT */
#ifdef CONFIG_RCU_FANOUT_LEAF
#define RCU_FANOUT_LEAF CONFIG_RCU_FANOUT_LEAF
#else /* #ifdef CONFIG_RCU_FANOUT_LEAF */
# ifdef CONFIG_64BIT
# define RCU_FANOUT_LEAF 64
# else
# define RCU_FANOUT_LEAF 32
# endif
#endif /* #else #ifdef CONFIG_RCU_FANOUT_LEAF */
#define RCU_FANOUT_1 (RCU_FANOUT_LEAF)
#define RCU_FANOUT_2 (RCU_FANOUT_1 * RCU_FANOUT)
#define RCU_FANOUT_3 (RCU_FANOUT_2 * RCU_FANOUT)
#define RCU_FANOUT_4 (RCU_FANOUT_3 * RCU_FANOUT)
#if NR_CPUS <= RCU_FANOUT_1
# define RCU_NUM_LVLS 1
@@ -170,7 +192,6 @@ struct rcu_node {
/* if there is no such task. If there */
/* is no current expedited grace period, */
/* then there can cannot be any such task. */
#ifdef CONFIG_RCU_BOOST
struct list_head *boost_tasks;
/* Pointer to first task that needs to be */
/* priority boosted, or NULL if no priority */
@@ -208,7 +229,6 @@ struct rcu_node {
unsigned long n_balk_nos;
/* Refused to boost: not sure why, though. */
/* This can happen due to race conditions. */
#endif /* #ifdef CONFIG_RCU_BOOST */
#ifdef CONFIG_RCU_NOCB_CPU
wait_queue_head_t nocb_gp_wq[2];
/* Place for rcu_nocb_kthread() to wait GP. */
@@ -519,14 +539,11 @@ extern struct list_head rcu_struct_flavors;
* RCU implementation internal declarations:
*/
extern struct rcu_state rcu_sched_state;
DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
extern struct rcu_state rcu_bh_state;
DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
#ifdef CONFIG_PREEMPT_RCU
extern struct rcu_state rcu_preempt_state;
DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
#endif /* #ifdef CONFIG_PREEMPT_RCU */
#ifdef CONFIG_RCU_BOOST

216
kernel/rcu/tree_plugin.h
View File

@@ -43,7 +43,17 @@ DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
DEFINE_PER_CPU(char, rcu_cpu_has_work);
#endif /* #ifdef CONFIG_RCU_BOOST */
#else /* #ifdef CONFIG_RCU_BOOST */
/*
* Some architectures do not define rt_mutexes, but if !CONFIG_RCU_BOOST,
* all uses are in dead code. Provide a definition to keep the compiler
* happy, but add WARN_ON_ONCE() to complain if used in the wrong place.
* This probably needs to be excluded from -rt builds.
*/
#define rt_mutex_owner(a) ({ WARN_ON_ONCE(1); NULL; })
#endif /* #else #ifdef CONFIG_RCU_BOOST */
#ifdef CONFIG_RCU_NOCB_CPU
static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
@@ -60,11 +70,11 @@ static void __init rcu_bootup_announce_oddness(void)
{
if (IS_ENABLED(CONFIG_RCU_TRACE))
pr_info("\tRCU debugfs-based tracing is enabled.\n");
if ((IS_ENABLED(CONFIG_64BIT) && CONFIG_RCU_FANOUT != 64) ||
(!IS_ENABLED(CONFIG_64BIT) && CONFIG_RCU_FANOUT != 32))
if ((IS_ENABLED(CONFIG_64BIT) && RCU_FANOUT != 64) ||
(!IS_ENABLED(CONFIG_64BIT) && RCU_FANOUT != 32))
pr_info("\tCONFIG_RCU_FANOUT set to non-default value of %d\n",
CONFIG_RCU_FANOUT);
if (IS_ENABLED(CONFIG_RCU_FANOUT_EXACT))
RCU_FANOUT);
if (rcu_fanout_exact)
pr_info("\tHierarchical RCU autobalancing is disabled.\n");
if (IS_ENABLED(CONFIG_RCU_FAST_NO_HZ))
pr_info("\tRCU dyntick-idle grace-period acceleration is enabled.\n");
@@ -76,10 +86,10 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tAdditional per-CPU info printed with stalls.\n");
if (NUM_RCU_LVL_4 != 0)
pr_info("\tFour-level hierarchy is enabled.\n");
if (CONFIG_RCU_FANOUT_LEAF != 16)
if (RCU_FANOUT_LEAF != 16)
pr_info("\tBuild-time adjustment of leaf fanout to %d.\n",
CONFIG_RCU_FANOUT_LEAF);
if (rcu_fanout_leaf != CONFIG_RCU_FANOUT_LEAF)
RCU_FANOUT_LEAF);
if (rcu_fanout_leaf != RCU_FANOUT_LEAF)
pr_info("\tBoot-time adjustment of leaf fanout to %d.\n", rcu_fanout_leaf);
if (nr_cpu_ids != NR_CPUS)
pr_info("\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);
@@ -90,7 +100,8 @@ static void __init rcu_bootup_announce_oddness(void)
#ifdef CONFIG_PREEMPT_RCU
RCU_STATE_INITIALIZER(rcu_preempt, 'p', call_rcu);
static struct rcu_state *rcu_state_p = &rcu_preempt_state;
static struct rcu_state *const rcu_state_p = &rcu_preempt_state;
static struct rcu_data __percpu *const rcu_data_p = &rcu_preempt_data;
static int rcu_preempted_readers_exp(struct rcu_node *rnp);
static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
@@ -116,11 +127,11 @@ static void __init rcu_bootup_announce(void)
*/
static void rcu_preempt_qs(void)
{
if (!__this_cpu_read(rcu_preempt_data.passed_quiesce)) {
if (!__this_cpu_read(rcu_data_p->passed_quiesce)) {
trace_rcu_grace_period(TPS("rcu_preempt"),
__this_cpu_read(rcu_preempt_data.gpnum),
__this_cpu_read(rcu_data_p->gpnum),
TPS("cpuqs"));
__this_cpu_write(rcu_preempt_data.passed_quiesce, 1);
__this_cpu_write(rcu_data_p->passed_quiesce, 1);
barrier(); /* Coordinate with rcu_preempt_check_callbacks(). */
current->rcu_read_unlock_special.b.need_qs = false;
}
@@ -150,7 +161,7 @@ static void rcu_preempt_note_context_switch(void)
!t->rcu_read_unlock_special.b.blocked) {
/* Possibly blocking in an RCU read-side critical section. */
rdp = this_cpu_ptr(rcu_preempt_state.rda);
rdp = this_cpu_ptr(rcu_state_p->rda);
rnp = rdp->mynode;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
@@ -180,10 +191,9 @@ static void rcu_preempt_note_context_switch(void)
if ((rnp->qsmask & rdp->grpmask) && rnp->gp_tasks != NULL) {
list_add(&t->rcu_node_entry, rnp->gp_tasks->prev);
rnp->gp_tasks = &t->rcu_node_entry;
#ifdef CONFIG_RCU_BOOST
if (rnp->boost_tasks != NULL)
if (IS_ENABLED(CONFIG_RCU_BOOST) &&
rnp->boost_tasks != NULL)
rnp->boost_tasks = rnp->gp_tasks;
#endif /* #ifdef CONFIG_RCU_BOOST */
} else {
list_add(&t->rcu_node_entry, &rnp->blkd_tasks);
if (rnp->qsmask & rdp->grpmask)
@@ -263,9 +273,7 @@ void rcu_read_unlock_special(struct task_struct *t)
bool empty_exp_now;
unsigned long flags;
struct list_head *np;
#ifdef CONFIG_RCU_BOOST
bool drop_boost_mutex = false;
#endif /* #ifdef CONFIG_RCU_BOOST */
struct rcu_node *rnp;
union rcu_special special;
@@ -307,9 +315,11 @@ void rcu_read_unlock_special(struct task_struct *t)
t->rcu_read_unlock_special.b.blocked = false;
/*
* Remove this task from the list it blocked on. The
* task can migrate while we acquire the lock, but at
* most one time. So at most two passes through loop.
* Remove this task from the list it blocked on. The task
* now remains queued on the rcu_node corresponding to
* the CPU it first blocked on, so the first attempt to
* acquire the task's rcu_node's ->lock will succeed.
* Keep the loop and add a WARN_ON() out of sheer paranoia.
*/
for (;;) {
rnp = t->rcu_blocked_node;
@@ -317,6 +327,7 @@ void rcu_read_unlock_special(struct task_struct *t)
smp_mb__after_unlock_lock();
if (rnp == t->rcu_blocked_node)
break;
WARN_ON_ONCE(1);
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
empty_norm = !rcu_preempt_blocked_readers_cgp(rnp);
@@ -331,12 +342,12 @@ void rcu_read_unlock_special(struct task_struct *t)
rnp->gp_tasks = np;
if (&t->rcu_node_entry == rnp->exp_tasks)
rnp->exp_tasks = np;
#ifdef CONFIG_RCU_BOOST
if (&t->rcu_node_entry == rnp->boost_tasks)
rnp->boost_tasks = np;
/* Snapshot ->boost_mtx ownership with rcu_node lock held. */
drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx) == t;
#endif /* #ifdef CONFIG_RCU_BOOST */
if (IS_ENABLED(CONFIG_RCU_BOOST)) {
if (&t->rcu_node_entry == rnp->boost_tasks)
rnp->boost_tasks = np;
/* Snapshot ->boost_mtx ownership w/rnp->lock held. */
drop_boost_mutex = rt_mutex_owner(&rnp->boost_mtx) == t;
}
/*
* If this was the last task on the current list, and if
@@ -353,24 +364,21 @@ void rcu_read_unlock_special(struct task_struct *t)
rnp->grplo,
rnp->grphi,
!!rnp->gp_tasks);
rcu_report_unblock_qs_rnp(&rcu_preempt_state,
rnp, flags);
rcu_report_unblock_qs_rnp(rcu_state_p, rnp, flags);
} else {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
#ifdef CONFIG_RCU_BOOST
/* Unboost if we were boosted. */
if (drop_boost_mutex)
if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
rt_mutex_unlock(&rnp->boost_mtx);
#endif /* #ifdef CONFIG_RCU_BOOST */
/*
* If this was the last task on the expedited lists,
* then we need to report up the rcu_node hierarchy.
*/
if (!empty_exp && empty_exp_now)
rcu_report_exp_rnp(&rcu_preempt_state, rnp, true);
rcu_report_exp_rnp(rcu_state_p, rnp, true);
} else {
local_irq_restore(flags);
}
@@ -390,7 +398,7 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
t = list_entry(rnp->gp_tasks,
t = list_entry(rnp->gp_tasks->prev,
struct task_struct, rcu_node_entry);
list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
sched_show_task(t);
@@ -447,7 +455,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp)
if (!rcu_preempt_blocked_readers_cgp(rnp))
return 0;
rcu_print_task_stall_begin(rnp);
t = list_entry(rnp->gp_tasks,
t = list_entry(rnp->gp_tasks->prev,
struct task_struct, rcu_node_entry);
list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) {
pr_cont(" P%d", t->pid);
@@ -491,8 +499,8 @@ static void rcu_preempt_check_callbacks(void)
return;
}
if (t->rcu_read_lock_nesting > 0 &&
__this_cpu_read(rcu_preempt_data.qs_pending) &&
!__this_cpu_read(rcu_preempt_data.passed_quiesce))
__this_cpu_read(rcu_data_p->qs_pending) &&
!__this_cpu_read(rcu_data_p->passed_quiesce))
t->rcu_read_unlock_special.b.need_qs = true;
}
@@ -500,7 +508,7 @@ static void rcu_preempt_check_callbacks(void)
static void rcu_preempt_do_callbacks(void)
{
rcu_do_batch(&rcu_preempt_state, this_cpu_ptr(&rcu_preempt_data));
rcu_do_batch(rcu_state_p, this_cpu_ptr(rcu_data_p));
}
#endif /* #ifdef CONFIG_RCU_BOOST */
@@ -510,7 +518,7 @@ static void rcu_preempt_do_callbacks(void)
*/
void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
{
__call_rcu(head, func, &rcu_preempt_state, -1, 0);
__call_rcu(head, func, rcu_state_p, -1, 0);
}
EXPORT_SYMBOL_GPL(call_rcu);
@@ -570,7 +578,7 @@ static int rcu_preempted_readers_exp(struct rcu_node *rnp)
static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
{
return !rcu_preempted_readers_exp(rnp) &&
ACCESS_ONCE(rnp->expmask) == 0;
READ_ONCE(rnp->expmask) == 0;
}
/*
@@ -711,12 +719,12 @@ sync_rcu_preempt_exp_init2(struct rcu_state *rsp, struct rcu_node *rnp)
void synchronize_rcu_expedited(void)
{
struct rcu_node *rnp;
struct rcu_state *rsp = &rcu_preempt_state;
struct rcu_state *rsp = rcu_state_p;
unsigned long snap;
int trycount = 0;
smp_mb(); /* Caller's modifications seen first by other CPUs. */
snap = ACCESS_ONCE(sync_rcu_preempt_exp_count) + 1;
snap = READ_ONCE(sync_rcu_preempt_exp_count) + 1;
smp_mb(); /* Above access cannot bleed into critical section. */
/*
@@ -740,7 +748,7 @@ void synchronize_rcu_expedited(void)
*/
while (!mutex_trylock(&sync_rcu_preempt_exp_mutex)) {
if (ULONG_CMP_LT(snap,
ACCESS_ONCE(sync_rcu_preempt_exp_count))) {
READ_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto mb_ret; /* Others did our work for us. */
}
@@ -752,7 +760,7 @@ void synchronize_rcu_expedited(void)
return;
}
}
if (ULONG_CMP_LT(snap, ACCESS_ONCE(sync_rcu_preempt_exp_count))) {
if (ULONG_CMP_LT(snap, READ_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto unlock_mb_ret; /* Others did our work for us. */
}
@@ -780,8 +788,7 @@ void synchronize_rcu_expedited(void)
/* Clean up and exit. */
smp_mb(); /* ensure expedited GP seen before counter increment. */
ACCESS_ONCE(sync_rcu_preempt_exp_count) =
sync_rcu_preempt_exp_count + 1;
WRITE_ONCE(sync_rcu_preempt_exp_count, sync_rcu_preempt_exp_count + 1);
unlock_mb_ret:
mutex_unlock(&sync_rcu_preempt_exp_mutex);
mb_ret:
@@ -799,7 +806,7 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
*/
void rcu_barrier(void)
{
_rcu_barrier(&rcu_preempt_state);
_rcu_barrier(rcu_state_p);
}
EXPORT_SYMBOL_GPL(rcu_barrier);
@@ -808,7 +815,7 @@ EXPORT_SYMBOL_GPL(rcu_barrier);
*/
static void __init __rcu_init_preempt(void)
{
rcu_init_one(&rcu_preempt_state, &rcu_preempt_data);
rcu_init_one(rcu_state_p, rcu_data_p);
}
/*
@@ -831,7 +838,8 @@ void exit_rcu(void)
#else /* #ifdef CONFIG_PREEMPT_RCU */
static struct rcu_state *rcu_state_p = &rcu_sched_state;
static struct rcu_state *const rcu_state_p = &rcu_sched_state;
static struct rcu_data __percpu *const rcu_data_p = &rcu_sched_data;
/*
* Tell them what RCU they are running.
@@ -994,8 +1002,8 @@ static int rcu_boost(struct rcu_node *rnp)
struct task_struct *t;
struct list_head *tb;
if (ACCESS_ONCE(rnp->exp_tasks) == NULL &&
ACCESS_ONCE(rnp->boost_tasks) == NULL)
if (READ_ONCE(rnp->exp_tasks) == NULL &&
READ_ONCE(rnp->boost_tasks) == NULL)
return 0; /* Nothing left to boost. */
raw_spin_lock_irqsave(&rnp->lock, flags);
@@ -1048,8 +1056,8 @@ static int rcu_boost(struct rcu_node *rnp)
rt_mutex_lock(&rnp->boost_mtx);
rt_mutex_unlock(&rnp->boost_mtx); /* Then keep lockdep happy. */
return ACCESS_ONCE(rnp->exp_tasks) != NULL ||
ACCESS_ONCE(rnp->boost_tasks) != NULL;
return READ_ONCE(rnp->exp_tasks) != NULL ||
READ_ONCE(rnp->boost_tasks) != NULL;
}
/*
@@ -1173,7 +1181,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
struct sched_param sp;
struct task_struct *t;
if (&rcu_preempt_state != rsp)
if (rcu_state_p != rsp)
return 0;
if (!rcu_scheduler_fully_active || rcu_rnp_online_cpus(rnp) == 0)
@@ -1367,13 +1375,12 @@ static void rcu_prepare_kthreads(int cpu)
* Because we not have RCU_FAST_NO_HZ, just check whether this CPU needs
* any flavor of RCU.
*/
#ifndef CONFIG_RCU_NOCB_CPU_ALL
int rcu_needs_cpu(unsigned long *delta_jiffies)
{
*delta_jiffies = ULONG_MAX;
return rcu_cpu_has_callbacks(NULL);
return IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL)
? 0 : rcu_cpu_has_callbacks(NULL);
}
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
/*
* Because we do not have RCU_FAST_NO_HZ, don't bother cleaning up
@@ -1462,7 +1469,7 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
* callbacks not yet ready to invoke.
*/
if ((rdp->completed != rnp->completed ||
unlikely(ACCESS_ONCE(rdp->gpwrap))) &&
unlikely(READ_ONCE(rdp->gpwrap))) &&
rdp->nxttail[RCU_DONE_TAIL] != rdp->nxttail[RCU_NEXT_TAIL])
note_gp_changes(rsp, rdp);
@@ -1480,11 +1487,15 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
*
* The caller must have disabled interrupts.
*/
#ifndef CONFIG_RCU_NOCB_CPU_ALL
int rcu_needs_cpu(unsigned long *dj)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL)) {
*dj = ULONG_MAX;
return 0;
}
/* Snapshot to detect later posting of non-lazy callback. */
rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted;
@@ -1511,7 +1522,6 @@ int rcu_needs_cpu(unsigned long *dj)
}
return 0;
}
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
/*
* Prepare a CPU for idle from an RCU perspective. The first major task
@@ -1525,7 +1535,6 @@ int rcu_needs_cpu(unsigned long *dj)
*/
static void rcu_prepare_for_idle(void)
{
#ifndef CONFIG_RCU_NOCB_CPU_ALL
bool needwake;
struct rcu_data *rdp;
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
@@ -1533,8 +1542,11 @@ static void rcu_prepare_for_idle(void)
struct rcu_state *rsp;
int tne;
if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL))
return;
/* Handle nohz enablement switches conservatively. */
tne = ACCESS_ONCE(tick_nohz_active);
tne = READ_ONCE(tick_nohz_active);
if (tne != rdtp->tick_nohz_enabled_snap) {
if (rcu_cpu_has_callbacks(NULL))
invoke_rcu_core(); /* force nohz to see update. */
@@ -1580,7 +1592,6 @@ static void rcu_prepare_for_idle(void)
if (needwake)
rcu_gp_kthread_wake(rsp);
}
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
}
/*
@@ -1590,12 +1601,11 @@ static void rcu_prepare_for_idle(void)
*/
static void rcu_cleanup_after_idle(void)
{
#ifndef CONFIG_RCU_NOCB_CPU_ALL
if (rcu_is_nocb_cpu(smp_processor_id()))
if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL) ||
rcu_is_nocb_cpu(smp_processor_id()))
return;
if (rcu_try_advance_all_cbs())
invoke_rcu_core();
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
}
/*
@@ -1760,7 +1770,7 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
atomic_read(&rdtp->dynticks) & 0xfff,
rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
ACCESS_ONCE(rsp->n_force_qs) - rsp->n_force_qs_gpstart,
READ_ONCE(rsp->n_force_qs) - rsp->n_force_qs_gpstart,
fast_no_hz);
}
@@ -1898,11 +1908,11 @@ static void wake_nocb_leader(struct rcu_data *rdp, bool force)
{
struct rcu_data *rdp_leader = rdp->nocb_leader;
if (!ACCESS_ONCE(rdp_leader->nocb_kthread))
if (!READ_ONCE(rdp_leader->nocb_kthread))
return;
if (ACCESS_ONCE(rdp_leader->nocb_leader_sleep) || force) {
if (READ_ONCE(rdp_leader->nocb_leader_sleep) || force) {
/* Prior smp_mb__after_atomic() orders against prior enqueue. */
ACCESS_ONCE(rdp_leader->nocb_leader_sleep) = false;
WRITE_ONCE(rdp_leader->nocb_leader_sleep, false);
wake_up(&rdp_leader->nocb_wq);
}
}
@@ -1934,14 +1944,14 @@ static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
ret = atomic_long_read(&rdp->nocb_q_count);
#ifdef CONFIG_PROVE_RCU
rhp = ACCESS_ONCE(rdp->nocb_head);
rhp = READ_ONCE(rdp->nocb_head);
if (!rhp)
rhp = ACCESS_ONCE(rdp->nocb_gp_head);
rhp = READ_ONCE(rdp->nocb_gp_head);
if (!rhp)
rhp = ACCESS_ONCE(rdp->nocb_follower_head);
rhp = READ_ONCE(rdp->nocb_follower_head);
/* Having no rcuo kthread but CBs after scheduler starts is bad! */
if (!ACCESS_ONCE(rdp->nocb_kthread) && rhp &&
if (!READ_ONCE(rdp->nocb_kthread) && rhp &&
rcu_scheduler_fully_active) {
/* RCU callback enqueued before CPU first came online??? */
pr_err("RCU: Never-onlined no-CBs CPU %d has CB %p\n",
@@ -1975,12 +1985,12 @@ static void __call_rcu_nocb_enqueue(struct rcu_data *rdp,
atomic_long_add(rhcount, &rdp->nocb_q_count);
/* rcu_barrier() relies on ->nocb_q_count add before xchg. */
old_rhpp = xchg(&rdp->nocb_tail, rhtp);
ACCESS_ONCE(*old_rhpp) = rhp;
WRITE_ONCE(*old_rhpp, rhp);
atomic_long_add(rhcount_lazy, &rdp->nocb_q_count_lazy);
smp_mb__after_atomic(); /* Store *old_rhpp before _wake test. */
/* If we are not being polled and there is a kthread, awaken it ... */
t = ACCESS_ONCE(rdp->nocb_kthread);
t = READ_ONCE(rdp->nocb_kthread);
if (rcu_nocb_poll || !t) {
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
TPS("WakeNotPoll"));
@@ -2118,7 +2128,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp)
for (;;) {
wait_event_interruptible(
rnp->nocb_gp_wq[c & 0x1],
(d = ULONG_CMP_GE(ACCESS_ONCE(rnp->completed), c)));
(d = ULONG_CMP_GE(READ_ONCE(rnp->completed), c)));
if (likely(d))
break;
WARN_ON(signal_pending(current));
@@ -2145,7 +2155,7 @@ wait_again:
if (!rcu_nocb_poll) {
trace_rcu_nocb_wake(my_rdp->rsp->name, my_rdp->cpu, "Sleep");
wait_event_interruptible(my_rdp->nocb_wq,
!ACCESS_ONCE(my_rdp->nocb_leader_sleep));
!READ_ONCE(my_rdp->nocb_leader_sleep));
/* Memory barrier handled by smp_mb() calls below and repoll. */
} else if (firsttime) {
firsttime = false; /* Don't drown trace log with "Poll"! */
@@ -2159,12 +2169,12 @@ wait_again:
*/
gotcbs = false;
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower) {
rdp->nocb_gp_head = ACCESS_ONCE(rdp->nocb_head);
rdp->nocb_gp_head = READ_ONCE(rdp->nocb_head);
if (!rdp->nocb_gp_head)
continue; /* No CBs here, try next follower. */
/* Move callbacks to wait-for-GP list, which is empty. */
ACCESS_ONCE(rdp->nocb_head) = NULL;
WRITE_ONCE(rdp->nocb_head, NULL);
rdp->nocb_gp_tail = xchg(&rdp->nocb_tail, &rdp->nocb_head);
gotcbs = true;
}
@@ -2184,7 +2194,7 @@ wait_again:
my_rdp->nocb_leader_sleep = true;
smp_mb(); /* Ensure _sleep true before scan. */
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower)
if (ACCESS_ONCE(rdp->nocb_head)) {
if (READ_ONCE(rdp->nocb_head)) {
/* Found CB, so short-circuit next wait. */
my_rdp->nocb_leader_sleep = false;
break;
@@ -2205,7 +2215,7 @@ wait_again:
/* Each pass through the following loop wakes a follower, if needed. */
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower) {
if (ACCESS_ONCE(rdp->nocb_head))
if (READ_ONCE(rdp->nocb_head))
my_rdp->nocb_leader_sleep = false;/* No need to sleep.*/
if (!rdp->nocb_gp_head)
continue; /* No CBs, so no need to wake follower. */
@@ -2241,7 +2251,7 @@ static void nocb_follower_wait(struct rcu_data *rdp)
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
"FollowerSleep");
wait_event_interruptible(rdp->nocb_wq,
ACCESS_ONCE(rdp->nocb_follower_head));
READ_ONCE(rdp->nocb_follower_head));
} else if (firsttime) {
/* Don't drown trace log with "Poll"! */
firsttime = false;
@@ -2282,10 +2292,10 @@ static int rcu_nocb_kthread(void *arg)
nocb_follower_wait(rdp);
/* Pull the ready-to-invoke callbacks onto local list. */
list = ACCESS_ONCE(rdp->nocb_follower_head);
list = READ_ONCE(rdp->nocb_follower_head);
BUG_ON(!list);
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, "WokeNonEmpty");
ACCESS_ONCE(rdp->nocb_follower_head) = NULL;
WRITE_ONCE(rdp->nocb_follower_head, NULL);
tail = xchg(&rdp->nocb_follower_tail, &rdp->nocb_follower_head);
/* Each pass through the following loop invokes a callback. */
@@ -2324,7 +2334,7 @@ static int rcu_nocb_kthread(void *arg)
/* Is a deferred wakeup of rcu_nocb_kthread() required? */
static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp)
{
return ACCESS_ONCE(rdp->nocb_defer_wakeup);
return READ_ONCE(rdp->nocb_defer_wakeup);
}
/* Do a deferred wakeup of rcu_nocb_kthread(). */
@@ -2334,8 +2344,8 @@ static void do_nocb_deferred_wakeup(struct rcu_data *rdp)
if (!rcu_nocb_need_deferred_wakeup(rdp))
return;
ndw = ACCESS_ONCE(rdp->nocb_defer_wakeup);
ACCESS_ONCE(rdp->nocb_defer_wakeup) = RCU_NOGP_WAKE_NOT;
ndw = READ_ONCE(rdp->nocb_defer_wakeup);
WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOGP_WAKE_NOT);
wake_nocb_leader(rdp, ndw == RCU_NOGP_WAKE_FORCE);
trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, TPS("DeferredWake"));
}
@@ -2448,7 +2458,7 @@ static void rcu_spawn_one_nocb_kthread(struct rcu_state *rsp, int cpu)
t = kthread_run(rcu_nocb_kthread, rdp_spawn,
"rcuo%c/%d", rsp->abbr, cpu);
BUG_ON(IS_ERR(t));
ACCESS_ONCE(rdp_spawn->nocb_kthread) = t;
WRITE_ONCE(rdp_spawn->nocb_kthread, t);
}
/*
@@ -2663,7 +2673,7 @@ static void rcu_sysidle_enter(int irq)
/* Record start of fully idle period. */
j = jiffies;
ACCESS_ONCE(rdtp->dynticks_idle_jiffies) = j;
WRITE_ONCE(rdtp->dynticks_idle_jiffies, j);
smp_mb__before_atomic();
atomic_inc(&rdtp->dynticks_idle);
smp_mb__after_atomic();
@@ -2681,7 +2691,7 @@ static void rcu_sysidle_enter(int irq)
*/
void rcu_sysidle_force_exit(void)
{
int oldstate = ACCESS_ONCE(full_sysidle_state);
int oldstate = READ_ONCE(full_sysidle_state);
int newoldstate;
/*
@@ -2794,7 +2804,7 @@ static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
smp_mb(); /* Read counters before timestamps. */
/* Pick up timestamps. */
j = ACCESS_ONCE(rdtp->dynticks_idle_jiffies);
j = READ_ONCE(rdtp->dynticks_idle_jiffies);
/* If this CPU entered idle more recently, update maxj timestamp. */
if (ULONG_CMP_LT(*maxj, j))
*maxj = j;
@@ -2831,11 +2841,11 @@ static unsigned long rcu_sysidle_delay(void)
static void rcu_sysidle(unsigned long j)
{
/* Check the current state. */
switch (ACCESS_ONCE(full_sysidle_state)) {
switch (READ_ONCE(full_sysidle_state)) {
case RCU_SYSIDLE_NOT:
/* First time all are idle, so note a short idle period. */
ACCESS_ONCE(full_sysidle_state) = RCU_SYSIDLE_SHORT;
WRITE_ONCE(full_sysidle_state, RCU_SYSIDLE_SHORT);
break;
case RCU_SYSIDLE_SHORT:
@@ -2873,7 +2883,7 @@ static void rcu_sysidle_cancel(void)
{
smp_mb();
if (full_sysidle_state > RCU_SYSIDLE_SHORT)
ACCESS_ONCE(full_sysidle_state) = RCU_SYSIDLE_NOT;
WRITE_ONCE(full_sysidle_state, RCU_SYSIDLE_NOT);
}
/*
@@ -2925,7 +2935,7 @@ static void rcu_sysidle_cb(struct rcu_head *rhp)
smp_mb(); /* grace period precedes setting inuse. */
rshp = container_of(rhp, struct rcu_sysidle_head, rh);
ACCESS_ONCE(rshp->inuse) = 0;
WRITE_ONCE(rshp->inuse, 0);
}
/*
@@ -2936,7 +2946,7 @@ static void rcu_sysidle_cb(struct rcu_head *rhp)
bool rcu_sys_is_idle(void)
{
static struct rcu_sysidle_head rsh;
int rss = ACCESS_ONCE(full_sysidle_state);
int rss = READ_ONCE(full_sysidle_state);
if (WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu))
return false;
@@ -2964,7 +2974,7 @@ bool rcu_sys_is_idle(void)
}
rcu_sysidle_report(rcu_state_p, isidle, maxj, false);
oldrss = rss;
rss = ACCESS_ONCE(full_sysidle_state);
rss = READ_ONCE(full_sysidle_state);
}
}
@@ -3048,10 +3058,10 @@ static bool rcu_nohz_full_cpu(struct rcu_state *rsp)
#ifdef CONFIG_NO_HZ_FULL
if (tick_nohz_full_cpu(smp_processor_id()) &&
(!rcu_gp_in_progress(rsp) ||
ULONG_CMP_LT(jiffies, ACCESS_ONCE(rsp->gp_start) + HZ)))
return 1;
ULONG_CMP_LT(jiffies, READ_ONCE(rsp->gp_start) + HZ)))
return true;
#endif /* #ifdef CONFIG_NO_HZ_FULL */
return 0;
return false;
}
/*
@@ -3077,7 +3087,7 @@ static void rcu_bind_gp_kthread(void)
static void rcu_dynticks_task_enter(void)
{
#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
ACCESS_ONCE(current->rcu_tasks_idle_cpu) = smp_processor_id();
WRITE_ONCE(current->rcu_tasks_idle_cpu, smp_processor_id());
#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
}
@@ -3085,6 +3095,6 @@ static void rcu_dynticks_task_enter(void)
static void rcu_dynticks_task_exit(void)
{
#if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL)
ACCESS_ONCE(current->rcu_tasks_idle_cpu) = -1;
WRITE_ONCE(current->rcu_tasks_idle_cpu, -1);
#endif /* #if defined(CONFIG_TASKS_RCU) && defined(CONFIG_NO_HZ_FULL) */
}

6
kernel/rcu/tree_trace.c
View File

@@ -277,7 +277,7 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
rsp->n_force_qs, rsp->n_force_qs_ngp,
rsp->n_force_qs - rsp->n_force_qs_ngp,
ACCESS_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
READ_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
if (rnp->level != level) {
seq_puts(m, "\n");
@@ -323,8 +323,8 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
struct rcu_node *rnp = &rsp->node[0];
raw_spin_lock_irqsave(&rnp->lock, flags);
completed = ACCESS_ONCE(rsp->completed);
gpnum = ACCESS_ONCE(rsp->gpnum);
completed = READ_ONCE(rsp->completed);
gpnum = READ_ONCE(rsp->gpnum);
if (completed == gpnum)
gpage = 0;
else

30
kernel/rcu/update.c
View File

@@ -150,14 +150,14 @@ void __rcu_read_unlock(void)
barrier(); /* critical section before exit code. */
t->rcu_read_lock_nesting = INT_MIN;
barrier(); /* assign before ->rcu_read_unlock_special load */
if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special.s)))
if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s)))
rcu_read_unlock_special(t);
barrier(); /* ->rcu_read_unlock_special load before assign */
t->rcu_read_lock_nesting = 0;
}
#ifdef CONFIG_PROVE_LOCKING
{
int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting);
int rrln = READ_ONCE(t->rcu_read_lock_nesting);
WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2);
}
@@ -389,17 +389,17 @@ module_param(rcu_cpu_stall_timeout, int, 0644);
int rcu_jiffies_till_stall_check(void)
{
int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout);
int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout);
/*
* Limit check must be consistent with the Kconfig limits
* for CONFIG_RCU_CPU_STALL_TIMEOUT.
*/
if (till_stall_check < 3) {
ACCESS_ONCE(rcu_cpu_stall_timeout) = 3;
WRITE_ONCE(rcu_cpu_stall_timeout, 3);
till_stall_check = 3;
} else if (till_stall_check > 300) {
ACCESS_ONCE(rcu_cpu_stall_timeout) = 300;
WRITE_ONCE(rcu_cpu_stall_timeout, 300);
till_stall_check = 300;
}
return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
@@ -550,12 +550,12 @@ static void check_holdout_task(struct task_struct *t,
{
int cpu;
if (!ACCESS_ONCE(t->rcu_tasks_holdout) ||
t->rcu_tasks_nvcsw != ACCESS_ONCE(t->nvcsw) ||
!ACCESS_ONCE(t->on_rq) ||
if (!READ_ONCE(t->rcu_tasks_holdout) ||
t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) ||
!READ_ONCE(t->on_rq) ||
(IS_ENABLED(CONFIG_NO_HZ_FULL) &&
!is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
ACCESS_ONCE(t->rcu_tasks_holdout) = false;
WRITE_ONCE(t->rcu_tasks_holdout, false);
list_del_init(&t->rcu_tasks_holdout_list);
put_task_struct(t);
return;
@@ -639,11 +639,11 @@ static int __noreturn rcu_tasks_kthread(void *arg)
*/
rcu_read_lock();
for_each_process_thread(g, t) {
if (t != current && ACCESS_ONCE(t->on_rq) &&
if (t != current && READ_ONCE(t->on_rq) &&
!is_idle_task(t)) {
get_task_struct(t);
t->rcu_tasks_nvcsw = ACCESS_ONCE(t->nvcsw);
ACCESS_ONCE(t->rcu_tasks_holdout) = true;
t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw);
WRITE_ONCE(t->rcu_tasks_holdout, true);
list_add(&t->rcu_tasks_holdout_list,
&rcu_tasks_holdouts);
}
@@ -672,7 +672,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
struct task_struct *t1;
schedule_timeout_interruptible(HZ);
rtst = ACCESS_ONCE(rcu_task_stall_timeout);
rtst = READ_ONCE(rcu_task_stall_timeout);
needreport = rtst > 0 &&
time_after(jiffies, lastreport + rtst);
if (needreport)
@@ -728,7 +728,7 @@ static void rcu_spawn_tasks_kthread(void)
static struct task_struct *rcu_tasks_kthread_ptr;
struct task_struct *t;
if (ACCESS_ONCE(rcu_tasks_kthread_ptr)) {
if (READ_ONCE(rcu_tasks_kthread_ptr)) {
smp_mb(); /* Ensure caller sees full kthread. */
return;
}
@@ -740,7 +740,7 @@ static void rcu_spawn_tasks_kthread(void)
t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
BUG_ON(IS_ERR(t));
smp_mb(); /* Ensure others see full kthread. */
ACCESS_ONCE(rcu_tasks_kthread_ptr) = t;
WRITE_ONCE(rcu_tasks_kthread_ptr, t);
mutex_unlock(&rcu_tasks_kthread_mutex);
}

26
kernel/torture.c
View File

@@ -409,7 +409,7 @@ static void (*torture_shutdown_hook)(void);
*/
void torture_shutdown_absorb(const char *title)
{
while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
pr_notice("torture thread %s parking due to system shutdown\n",
title);
schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
@@ -480,9 +480,9 @@ static int torture_shutdown_notify(struct notifier_block *unused1,
unsigned long unused2, void *unused3)
{
mutex_lock(&fullstop_mutex);
if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN;
WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
} else {
pr_warn("Concurrent rmmod and shutdown illegal!\n");
}
@@ -523,13 +523,13 @@ static int stutter;
*/
void stutter_wait(const char *title)
{
while (ACCESS_ONCE(stutter_pause_test) ||
(torture_runnable && !ACCESS_ONCE(*torture_runnable))) {
while (READ_ONCE(stutter_pause_test) ||
(torture_runnable && !READ_ONCE(*torture_runnable))) {
if (stutter_pause_test)
if (ACCESS_ONCE(stutter_pause_test) == 1)
if (READ_ONCE(stutter_pause_test) == 1)
schedule_timeout_interruptible(1);
else
while (ACCESS_ONCE(stutter_pause_test))
while (READ_ONCE(stutter_pause_test))
cond_resched();
else
schedule_timeout_interruptible(round_jiffies_relative(HZ));
@@ -549,14 +549,14 @@ static int torture_stutter(void *arg)
if (!torture_must_stop()) {
if (stutter > 1) {
schedule_timeout_interruptible(stutter - 1);
ACCESS_ONCE(stutter_pause_test) = 2;
WRITE_ONCE(stutter_pause_test, 2);
}
schedule_timeout_interruptible(1);
ACCESS_ONCE(stutter_pause_test) = 1;
WRITE_ONCE(stutter_pause_test, 1);
}
if (!torture_must_stop())
schedule_timeout_interruptible(stutter);
ACCESS_ONCE(stutter_pause_test) = 0;
WRITE_ONCE(stutter_pause_test, 0);
torture_shutdown_absorb("torture_stutter");
} while (!torture_must_stop());
torture_kthread_stopping("torture_stutter");
@@ -642,13 +642,13 @@ EXPORT_SYMBOL_GPL(torture_init_end);
bool torture_cleanup_begin(void)
{
mutex_lock(&fullstop_mutex);
if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
pr_warn("Concurrent rmmod and shutdown illegal!\n");
mutex_unlock(&fullstop_mutex);
schedule_timeout_uninterruptible(10);
return true;
}
ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;
WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
mutex_unlock(&fullstop_mutex);
torture_shutdown_cleanup();
torture_shuffle_cleanup();
@@ -681,7 +681,7 @@ EXPORT_SYMBOL_GPL(torture_must_stop);
*/
bool torture_must_stop_irq(void)
{
return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
}
EXPORT_SYMBOL_GPL(torture_must_stop_irq);