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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:
 "The main changes in this cycle are:

   - Documentation updates

   - RCU CPU stall-warning updates

   - Torture-test updates

   - Miscellaneous fixes

  Size wise the biggest updates are to documentation. Excluding
  documentation most of the code increase comes from a single commit
  which expands debugging"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  srcu: Add parameters to SRCU docbook comments
  doc: Rewrite confusing statement about memory barriers
  memory-barriers.txt: Fix typo in pairing example
  rcu/segcblist: Include rcupdate.h
  rcu: Add extended-quiescent-state testing advice
  rcu: Suppress lockdep false-positive ->boost_mtx complaints
  rcu: Do not include rtmutex_common.h unconditionally
  torture: Provide TMPDIR environment variable to specify tmpdir
  rcutorture: Dump writer stack if stalled
  rcutorture: Add interrupt-disable capability to stall-warning tests
  rcu: Suppress RCU CPU stall warnings while dumping trace
  rcu: Turn off tracing before dumping trace
  rcu: Make RCU CPU stall warnings check for irq-disabled CPUs
  sched,rcu: Make cond_resched() provide RCU quiescent state
  sched: Make resched_cpu() unconditional
  irq_work: Map irq_work_on_queue() to irq_work_on() in !SMP
  rcu: Create call_rcu_tasks() kthread at boot time
  rcu: Fix up pending cbs check in rcu_prepare_for_idle
  memory-barriers: Rework multicopy-atomicity section
  memory-barriers: Replace uses of "transitive"
  ...
This commit is contained in:
Linus Torvalds
2017-11-13 12:18:10 -08:00
parent f08d8bcc12 72bc286b81
commit 6098850e7e
35 changed files with 14590 additions and 248 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/rcu/rcu.h
View File

@@ -203,6 +203,21 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
extern int rcu_cpu_stall_suppress;
int rcu_jiffies_till_stall_check(void);
#define rcu_ftrace_dump_stall_suppress() \
do { \
if (!rcu_cpu_stall_suppress) \
rcu_cpu_stall_suppress = 3; \
} while (0)
#define rcu_ftrace_dump_stall_unsuppress() \
do { \
if (rcu_cpu_stall_suppress == 3) \
rcu_cpu_stall_suppress = 0; \
} while (0)
#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
#define rcu_ftrace_dump_stall_suppress()
#define rcu_ftrace_dump_stall_unsuppress()
#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
/*
@@ -220,8 +235,12 @@ do { \
static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
\
if (!atomic_read(&___rfd_beenhere) && \
!atomic_xchg(&___rfd_beenhere, 1)) \
!atomic_xchg(&___rfd_beenhere, 1)) { \
tracing_off(); \
rcu_ftrace_dump_stall_suppress(); \
ftrace_dump(oops_dump_mode); \
rcu_ftrace_dump_stall_unsuppress(); \
} \
} while (0)
void rcu_early_boot_tests(void);

1
kernel/rcu/rcu_segcblist.c
View File

@@ -23,6 +23,7 @@
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/rcupdate.h>
#include "rcu_segcblist.h"

24
kernel/rcu/rcutorture.c
View File

@@ -51,6 +51,7 @@
#include <asm/byteorder.h>
#include <linux/torture.h>
#include <linux/vmalloc.h>
#include <linux/sched/debug.h>
#include "rcu.h"
@@ -89,6 +90,7 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
torture_param(int, stall_cpu_holdoff, 10,
"Time to wait before starting stall (s).");
torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
torture_param(int, stat_interval, 60,
"Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of seconds to run/halt test");
@@ -1239,6 +1241,7 @@ rcu_torture_stats_print(void)
long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
static unsigned long rtcv_snap = ULONG_MAX;
static bool splatted;
struct task_struct *wtp;
for_each_possible_cpu(cpu) {
@@ -1324,6 +1327,10 @@ rcu_torture_stats_print(void)
gpnum, completed, flags,
wtp == NULL ? ~0UL : wtp->state,
wtp == NULL ? -1 : (int)task_cpu(wtp));
if (!splatted && wtp) {
sched_show_task(wtp);
splatted = true;
}
show_rcu_gp_kthreads();
rcu_ftrace_dump(DUMP_ALL);
}
@@ -1357,7 +1364,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
"test_boost=%d/%d test_boost_interval=%d "
"test_boost_duration=%d shutdown_secs=%d "
"stall_cpu=%d stall_cpu_holdoff=%d "
"stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
"n_barrier_cbs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
@@ -1365,7 +1372,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
test_boost, cur_ops->can_boost,
test_boost_interval, test_boost_duration, shutdown_secs,
stall_cpu, stall_cpu_holdoff,
stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
n_barrier_cbs,
onoff_interval, onoff_holdoff);
}
@@ -1430,12 +1437,19 @@ static int rcu_torture_stall(void *args)
if (!kthread_should_stop()) {
stop_at = get_seconds() + stall_cpu;
/* RCU CPU stall is expected behavior in following code. */
pr_alert("rcu_torture_stall start.\n");
rcu_read_lock();
preempt_disable();
if (stall_cpu_irqsoff)
local_irq_disable();
else
preempt_disable();
pr_alert("rcu_torture_stall start on CPU %d.\n",
smp_processor_id());
while (ULONG_CMP_LT(get_seconds(), stop_at))
continue; /* Induce RCU CPU stall warning. */
preempt_enable();
if (stall_cpu_irqsoff)
local_irq_enable();
else
preempt_enable();
rcu_read_unlock();
pr_alert("rcu_torture_stall end.\n");
}

159
kernel/rcu/tree.c
View File

@@ -534,8 +534,8 @@ module_param(rcu_kick_kthreads, bool, 0644);
* How long the grace period must be before we start recruiting
* quiescent-state help from rcu_note_context_switch().
*/
static ulong jiffies_till_sched_qs = HZ / 20;
module_param(jiffies_till_sched_qs, ulong, 0644);
static ulong jiffies_till_sched_qs = HZ / 10;
module_param(jiffies_till_sched_qs, ulong, 0444);
static bool rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp,
struct rcu_data *rdp);
@@ -837,6 +837,9 @@ static void rcu_eqs_enter(bool user)
* We crowbar the ->dynticks_nesting field to zero to allow for
* the possibility of usermode upcalls having messed up our count
* of interrupt nesting level during the prior busy period.
*
* If you add or remove a call to rcu_idle_enter(), be sure to test with
* CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_idle_enter(void)
{
@@ -852,6 +855,9 @@ void rcu_idle_enter(void)
* is permitted between this call and rcu_user_exit(). This way the
* CPU doesn't need to maintain the tick for RCU maintenance purposes
* when the CPU runs in userspace.
*
* If you add or remove a call to rcu_user_enter(), be sure to test with
* CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_user_enter(void)
{
@@ -875,6 +881,9 @@ void rcu_user_enter(void)
* Use things like work queues to work around this limitation.
*
* You have been warned.
*
* If you add or remove a call to rcu_irq_exit(), be sure to test with
* CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_exit(void)
{
@@ -899,6 +908,9 @@ void rcu_irq_exit(void)
/*
* Wrapper for rcu_irq_exit() where interrupts are enabled.
*
* If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
* with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_exit_irqson(void)
{
@@ -971,6 +983,9 @@ static void rcu_eqs_exit(bool user)
* allow for the possibility of usermode upcalls messing up our count
* of interrupt nesting level during the busy period that is just
* now starting.
*
* If you add or remove a call to rcu_idle_exit(), be sure to test with
* CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_idle_exit(void)
{
@@ -987,6 +1002,9 @@ void rcu_idle_exit(void)
*
* Exit RCU idle mode while entering the kernel because it can
* run a RCU read side critical section anytime.
*
* If you add or remove a call to rcu_user_exit(), be sure to test with
* CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_user_exit(void)
{
@@ -1012,6 +1030,9 @@ void rcu_user_exit(void)
* Use things like work queues to work around this limitation.
*
* You have been warned.
*
* If you add or remove a call to rcu_irq_enter(), be sure to test with
* CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_enter(void)
{
@@ -1037,6 +1058,9 @@ void rcu_irq_enter(void)
/*
* Wrapper for rcu_irq_enter() where interrupts are enabled.
*
* If you add or remove a call to rcu_irq_enter_irqson(), be sure to test
* with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_irq_enter_irqson(void)
{
@@ -1055,6 +1079,9 @@ void rcu_irq_enter_irqson(void)
* that the CPU is active. This implementation permits nested NMIs, as
* long as the nesting level does not overflow an int. (You will probably
* run out of stack space first.)
*
* If you add or remove a call to rcu_nmi_enter(), be sure to test
* with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_nmi_enter(void)
{
@@ -1087,6 +1114,9 @@ void rcu_nmi_enter(void)
* RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
* to let the RCU grace-period handling know that the CPU is back to
* being RCU-idle.
*
* If you add or remove a call to rcu_nmi_exit(), be sure to test
* with CONFIG_RCU_EQS_DEBUG=y.
*/
void rcu_nmi_exit(void)
{
@@ -1206,6 +1236,22 @@ static int rcu_is_cpu_rrupt_from_idle(void)
return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 1;
}
/*
* We are reporting a quiescent state on behalf of some other CPU, so
* it is our responsibility to check for and handle potential overflow
* of the rcu_node ->gpnum counter with respect to the rcu_data counters.
* After all, the CPU might be in deep idle state, and thus executing no
* code whatsoever.
*/
static void rcu_gpnum_ovf(struct rcu_node *rnp, struct rcu_data *rdp)
{
lockdep_assert_held(&rnp->lock);
if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4, rnp->gpnum))
WRITE_ONCE(rdp->gpwrap, true);
if (ULONG_CMP_LT(rdp->rcu_iw_gpnum + ULONG_MAX / 4, rnp->gpnum))
rdp->rcu_iw_gpnum = rnp->gpnum + ULONG_MAX / 4;
}
/*
* Snapshot the specified CPU's dynticks counter so that we can later
* credit them with an implicit quiescent state. Return 1 if this CPU
@@ -1216,14 +1262,33 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp)
rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks);
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
if (ULONG_CMP_LT(READ_ONCE(rdp->gpnum) + ULONG_MAX / 4,
rdp->mynode->gpnum))
WRITE_ONCE(rdp->gpwrap, true);
rcu_gpnum_ovf(rdp->mynode, rdp);
return 1;
}
return 0;
}
/*
* Handler for the irq_work request posted when a grace period has
* gone on for too long, but not yet long enough for an RCU CPU
* stall warning. Set state appropriately, but just complain if
* there is unexpected state on entry.
*/
static void rcu_iw_handler(struct irq_work *iwp)
{
struct rcu_data *rdp;
struct rcu_node *rnp;
rdp = container_of(iwp, struct rcu_data, rcu_iw);
rnp = rdp->mynode;
raw_spin_lock_rcu_node(rnp);
if (!WARN_ON_ONCE(!rdp->rcu_iw_pending)) {
rdp->rcu_iw_gpnum = rnp->gpnum;
rdp->rcu_iw_pending = false;
}
raw_spin_unlock_rcu_node(rnp);
}
/*
* Return true if the specified CPU has passed through a quiescent
* state by virtue of being in or having passed through an dynticks
@@ -1235,8 +1300,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
unsigned long jtsq;
bool *rnhqp;
bool *ruqp;
unsigned long rjtsc;
struct rcu_node *rnp;
struct rcu_node *rnp = rdp->mynode;
/*
* If the CPU passed through or entered a dynticks idle phase with
@@ -1249,34 +1313,25 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
if (rcu_dynticks_in_eqs_since(rdp->dynticks, rdp->dynticks_snap)) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("dti"));
rdp->dynticks_fqs++;
rcu_gpnum_ovf(rnp, rdp);
return 1;
}
/* Compute and saturate jiffies_till_sched_qs. */
jtsq = jiffies_till_sched_qs;
rjtsc = rcu_jiffies_till_stall_check();
if (jtsq > rjtsc / 2) {
WRITE_ONCE(jiffies_till_sched_qs, rjtsc);
jtsq = rjtsc / 2;
} else if (jtsq < 1) {
WRITE_ONCE(jiffies_till_sched_qs, 1);
jtsq = 1;
}
/*
* Has this CPU encountered a cond_resched_rcu_qs() since the
* beginning of the grace period? For this to be the case,
* the CPU has to have noticed the current grace period. This
* might not be the case for nohz_full CPUs looping in the kernel.
*/
rnp = rdp->mynode;
jtsq = jiffies_till_sched_qs;
ruqp = per_cpu_ptr(&rcu_dynticks.rcu_urgent_qs, rdp->cpu);
if (time_after(jiffies, rdp->rsp->gp_start + jtsq) &&
READ_ONCE(rdp->rcu_qs_ctr_snap) != per_cpu(rcu_dynticks.rcu_qs_ctr, rdp->cpu) &&
READ_ONCE(rdp->gpnum) == rnp->gpnum && !rdp->gpwrap) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("rqc"));
rcu_gpnum_ovf(rnp, rdp);
return 1;
} else {
} else if (time_after(jiffies, rdp->rsp->gp_start + jtsq)) {
/* Load rcu_qs_ctr before store to rcu_urgent_qs. */
smp_store_release(ruqp, true);
}
@@ -1285,6 +1340,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp))) {
trace_rcu_fqs(rdp->rsp->name, rdp->gpnum, rdp->cpu, TPS("ofl"));
rdp->offline_fqs++;
rcu_gpnum_ovf(rnp, rdp);
return 1;
}
@@ -1304,10 +1360,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
* updates are only once every few jiffies, the probability of
* lossage (and thus of slight grace-period extension) is
* quite low.
*
* Note that if the jiffies_till_sched_qs boot/sysfs parameter
* is set too high, we override with half of the RCU CPU stall
* warning delay.
*/
rnhqp = &per_cpu(rcu_dynticks.rcu_need_heavy_qs, rdp->cpu);
if (!READ_ONCE(*rnhqp) &&
@@ -1316,15 +1368,26 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
WRITE_ONCE(*rnhqp, true);
/* Store rcu_need_heavy_qs before rcu_urgent_qs. */
smp_store_release(ruqp, true);
rdp->rsp->jiffies_resched += 5; /* Re-enable beating. */
rdp->rsp->jiffies_resched += jtsq; /* Re-enable beating. */
}
/*
* If more than halfway to RCU CPU stall-warning time, do
* a resched_cpu() to try to loosen things up a bit.
* If more than halfway to RCU CPU stall-warning time, do a
* resched_cpu() to try to loosen things up a bit. Also check to
* see if the CPU is getting hammered with interrupts, but only
* once per grace period, just to keep the IPIs down to a dull roar.
*/
if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2)
if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2) {
resched_cpu(rdp->cpu);
if (IS_ENABLED(CONFIG_IRQ_WORK) &&
!rdp->rcu_iw_pending && rdp->rcu_iw_gpnum != rnp->gpnum &&
(rnp->ffmask & rdp->grpmask)) {
init_irq_work(&rdp->rcu_iw, rcu_iw_handler);
rdp->rcu_iw_pending = true;
rdp->rcu_iw_gpnum = rnp->gpnum;
irq_work_queue_on(&rdp->rcu_iw, rdp->cpu);
}
}
return 0;
}
@@ -1513,6 +1576,7 @@ static void print_cpu_stall(struct rcu_state *rsp)
{
int cpu;
unsigned long flags;
struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
struct rcu_node *rnp = rcu_get_root(rsp);
long totqlen = 0;
@@ -1528,7 +1592,9 @@ static void print_cpu_stall(struct rcu_state *rsp)
*/
pr_err("INFO: %s self-detected stall on CPU", rsp->name);
print_cpu_stall_info_begin();
raw_spin_lock_irqsave_rcu_node(rdp->mynode, flags);
print_cpu_stall_info(rsp, smp_processor_id());
raw_spin_unlock_irqrestore_rcu_node(rdp->mynode, flags);
print_cpu_stall_info_end();
for_each_possible_cpu(cpu)
totqlen += rcu_segcblist_n_cbs(&per_cpu_ptr(rsp->rda,
@@ -1922,6 +1988,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
rdp->core_needs_qs = need_gp;
zero_cpu_stall_ticks(rdp);
WRITE_ONCE(rdp->gpwrap, false);
rcu_gpnum_ovf(rnp, rdp);
}
return ret;
}
@@ -3702,6 +3769,8 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->cpu_no_qs.b.norm = true;
rdp->rcu_qs_ctr_snap = per_cpu(rcu_dynticks.rcu_qs_ctr, cpu);
rdp->core_needs_qs = false;
rdp->rcu_iw_pending = false;
rdp->rcu_iw_gpnum = rnp->gpnum - 1;
trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
@@ -3739,10 +3808,24 @@ static void rcutree_affinity_setting(unsigned int cpu, int outgoing)
*/
int rcutree_online_cpu(unsigned int cpu)
{
sync_sched_exp_online_cleanup(cpu);
rcutree_affinity_setting(cpu, -1);
unsigned long flags;
struct rcu_data *rdp;
struct rcu_node *rnp;
struct rcu_state *rsp;
for_each_rcu_flavor(rsp) {
rdp = per_cpu_ptr(rsp->rda, cpu);
rnp = rdp->mynode;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rnp->ffmask |= rdp->grpmask;
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
if (IS_ENABLED(CONFIG_TREE_SRCU))
srcu_online_cpu(cpu);
if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
return 0; /* Too early in boot for scheduler work. */
sync_sched_exp_online_cleanup(cpu);
rcutree_affinity_setting(cpu, -1);
return 0;
}
@@ -3752,6 +3835,19 @@ int rcutree_online_cpu(unsigned int cpu)
*/
int rcutree_offline_cpu(unsigned int cpu)
{
unsigned long flags;
struct rcu_data *rdp;
struct rcu_node *rnp;
struct rcu_state *rsp;
for_each_rcu_flavor(rsp) {
rdp = per_cpu_ptr(rsp->rda, cpu);
rnp = rdp->mynode;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rnp->ffmask &= ~rdp->grpmask;
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}
rcutree_affinity_setting(cpu, cpu);
if (IS_ENABLED(CONFIG_TREE_SRCU))
srcu_offline_cpu(cpu);
@@ -4200,8 +4296,7 @@ void __init rcu_init(void)
for_each_online_cpu(cpu) {
rcutree_prepare_cpu(cpu);
rcu_cpu_starting(cpu);
if (IS_ENABLED(CONFIG_TREE_SRCU))
srcu_online_cpu(cpu);
rcutree_online_cpu(cpu);
}
}

5
kernel/rcu/tree.h
View File

@@ -103,6 +103,7 @@ struct rcu_node {
/* Online CPUs for next expedited GP. */
/* Any CPU that has ever been online will */
/* have its bit set. */
unsigned long ffmask; /* Fully functional CPUs. */
unsigned long grpmask; /* Mask to apply to parent qsmask. */
/* Only one bit will be set in this mask. */
int grplo; /* lowest-numbered CPU or group here. */
@@ -285,6 +286,10 @@ struct rcu_data {
/* 8) RCU CPU stall data. */
unsigned int softirq_snap; /* Snapshot of softirq activity. */
/* ->rcu_iw* fields protected by leaf rcu_node ->lock. */
struct irq_work rcu_iw; /* Check for non-irq activity. */
bool rcu_iw_pending; /* Is ->rcu_iw pending? */
unsigned long rcu_iw_gpnum; /* ->gpnum associated with ->rcu_iw. */
int cpu;
struct rcu_state *rsp;

14
kernel/rcu/tree_plugin.h
View File

@@ -54,6 +54,7 @@ DEFINE_PER_CPU(char, rcu_cpu_has_work);
* This probably needs to be excluded from -rt builds.
*/
#define rt_mutex_owner(a) ({ WARN_ON_ONCE(1); NULL; })
#define rt_mutex_futex_unlock(x) WARN_ON_ONCE(1)
#endif /* #else #ifdef CONFIG_RCU_BOOST */
@@ -530,7 +531,7 @@ void rcu_read_unlock_special(struct task_struct *t)
/* Unboost if we were boosted. */
if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
rt_mutex_unlock(&rnp->boost_mtx);
rt_mutex_futex_unlock(&rnp->boost_mtx);
/*
* If this was the last task on the expedited lists,
@@ -911,8 +912,6 @@ void exit_rcu(void)
#ifdef CONFIG_RCU_BOOST
#include "../locking/rtmutex_common.h"
static void rcu_wake_cond(struct task_struct *t, int status)
{
/*
@@ -1507,7 +1506,7 @@ static void rcu_prepare_for_idle(void)
rdtp->last_accelerate = jiffies;
for_each_rcu_flavor(rsp) {
rdp = this_cpu_ptr(rsp->rda);
if (rcu_segcblist_pend_cbs(&rdp->cblist))
if (!rcu_segcblist_pend_cbs(&rdp->cblist))
continue;
rnp = rdp->mynode;
raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
@@ -1671,6 +1670,7 @@ static void print_cpu_stall_info_begin(void)
*/
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
{
unsigned long delta;
char fast_no_hz[72];
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_dynticks *rdtp = rdp->dynticks;
@@ -1685,11 +1685,15 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
ticks_value = rsp->gpnum - rdp->gpnum;
}
print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
pr_err("\t%d-%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
delta = rdp->mynode->gpnum - rdp->rcu_iw_gpnum;
pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
cpu,
"O."[!!cpu_online(cpu)],
"o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
"N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)],
!IS_ENABLED(CONFIG_IRQ_WORK) ? '?' :
rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
"!."[!delta],
ticks_value, ticks_title,
rcu_dynticks_snap(rdtp) & 0xfff,
rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,

25
kernel/rcu/update.c
View File

@@ -494,6 +494,7 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
#endif
int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
module_param(rcu_cpu_stall_suppress, int, 0644);
@@ -575,7 +576,6 @@ DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu);
static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT;
module_param(rcu_task_stall_timeout, int, 0644);
static void rcu_spawn_tasks_kthread(void);
static struct task_struct *rcu_tasks_kthread_ptr;
/**
@@ -600,7 +600,6 @@ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
{
unsigned long flags;
bool needwake;
bool havetask = READ_ONCE(rcu_tasks_kthread_ptr);
rhp->next = NULL;
rhp->func = func;
@@ -610,11 +609,8 @@ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
rcu_tasks_cbs_tail = &rhp->next;
raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
/* We can't create the thread unless interrupts are enabled. */
if ((needwake && havetask) ||
(!havetask && !irqs_disabled_flags(flags))) {
rcu_spawn_tasks_kthread();
if (needwake && READ_ONCE(rcu_tasks_kthread_ptr))
wake_up(&rcu_tasks_cbs_wq);
}
}
EXPORT_SYMBOL_GPL(call_rcu_tasks);
@@ -853,27 +849,18 @@ static int __noreturn rcu_tasks_kthread(void *arg)
}
}
/* Spawn rcu_tasks_kthread() at first call to call_rcu_tasks(). */
static void rcu_spawn_tasks_kthread(void)
/* Spawn rcu_tasks_kthread() at core_initcall() time. */
static int __init rcu_spawn_tasks_kthread(void)
{
static DEFINE_MUTEX(rcu_tasks_kthread_mutex);
struct task_struct *t;
if (READ_ONCE(rcu_tasks_kthread_ptr)) {
smp_mb(); /* Ensure caller sees full kthread. */
return;
}
mutex_lock(&rcu_tasks_kthread_mutex);
if (rcu_tasks_kthread_ptr) {
mutex_unlock(&rcu_tasks_kthread_mutex);
return;
}
t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
BUG_ON(IS_ERR(t));
smp_mb(); /* Ensure others see full kthread. */
WRITE_ONCE(rcu_tasks_kthread_ptr, t);
mutex_unlock(&rcu_tasks_kthread_mutex);
return 0;
}
core_initcall(rcu_spawn_tasks_kthread);
/* Do the srcu_read_lock() for the above synchronize_srcu(). */
void exit_tasks_rcu_start(void)