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Merge branches 'cond_resched.2017.12.04a', 'dyntick.2017.11.28a', 'fixes.2017.12.11a', 'srbd.2017.12.05a' and 'torture.2017.12.11a' into HEAD

Browse Source 
cond_resched.2017.12.04a: Convert cond_resched_rcu_qs() to cond_resched()
dyntick.2017.11.28a: Make RCU dynticks handle interrupts from NMI
fixes.2017.12.11a: Miscellaneous fixes
srbd.2017.12.05a: Remove now-redundant smp_read_barrier_depends()
torture.2017.12.11a: Torture-testing update
This commit is contained in:
Paul E. McKenney
2017-12-11 09:21:58 -08:00
parent dc259accec 584c005951 84b12b752f 3a5db0b108 29d3939084
commit 1dfa55e019
72 changed files with 482 additions and 729 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
kernel/rcu/rcu.h
View File

@@ -30,31 +30,8 @@
#define RCU_TRACE(stmt)
#endif /* #else #ifdef CONFIG_RCU_TRACE */
/*
* Process-level increment to ->dynticks_nesting field. This allows for
* architectures that use half-interrupts and half-exceptions from
* process context.
*
* DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH
* that counts the number of process-based reasons why RCU cannot
* consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE
* is the value used to increment or decrement this field.
*
* The rest of the bits could in principle be used to count interrupts,
* but this would mean that a negative-one value in the interrupt
* field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field.
* We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK
* that is set to DYNTICK_TASK_FLAG upon initial exit from idle.
* The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon
* initial exit from idle.
*/
#define DYNTICK_TASK_NEST_WIDTH 7
#define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1)
#define DYNTICK_TASK_NEST_MASK (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1)
#define DYNTICK_TASK_FLAG ((DYNTICK_TASK_NEST_VALUE / 8) * 2)
#define DYNTICK_TASK_MASK ((DYNTICK_TASK_NEST_VALUE / 8) * 3)
#define DYNTICK_TASK_EXIT_IDLE (DYNTICK_TASK_NEST_VALUE + \
DYNTICK_TASK_FLAG)
/* Offset to allow for unmatched rcu_irq_{enter,exit}(). */
#define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1)
/*

6
kernel/rcu/rcuperf.c
View File

@@ -106,10 +106,6 @@ static int rcu_perf_writer_state;
#define MAX_MEAS 10000
#define MIN_MEAS 100
static int perf_runnable = IS_ENABLED(MODULE);
module_param(perf_runnable, int, 0444);
MODULE_PARM_DESC(perf_runnable, "Start rcuperf at boot");
/*
* Operations vector for selecting different types of tests.
*/
@@ -646,7 +642,7 @@ rcu_perf_init(void)
&tasks_ops,
};
if (!torture_init_begin(perf_type, verbose, &perf_runnable))
if (!torture_init_begin(perf_type, verbose))
return -EBUSY;
/* Process args and tell the world that the perf'er is on the job. */

12
kernel/rcu/rcutorture.c
View File

@@ -187,10 +187,6 @@ static const char *rcu_torture_writer_state_getname(void)
return rcu_torture_writer_state_names[i];
}
static int torture_runnable = IS_ENABLED(MODULE);
module_param(torture_runnable, int, 0444);
MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
#define rcu_can_boost() 1
#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
@@ -315,11 +311,9 @@ static void rcu_read_delay(struct torture_random_state *rrsp)
}
if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
udelay(shortdelay_us);
#ifdef CONFIG_PREEMPT
if (!preempt_count() &&
!(torture_random(rrsp) % (nrealreaders * 20000)))
preempt_schedule(); /* No QS if preempt_disable() in effect */
#endif
!(torture_random(rrsp) % (nrealreaders * 500)))
torture_preempt_schedule(); /* QS only if preemptible. */
}
static void rcu_torture_read_unlock(int idx) __releases(RCU)
@@ -1731,7 +1725,7 @@ rcu_torture_init(void)
&sched_ops, &tasks_ops,
};
if (!torture_init_begin(torture_type, verbose, &torture_runnable))
if (!torture_init_begin(torture_type, verbose))
return -EBUSY;
/* Process args and tell the world that the torturer is on the job. */

109
kernel/rcu/srcutree.c
View File

@@ -53,6 +53,33 @@ static void srcu_invoke_callbacks(struct work_struct *work);
static void srcu_reschedule(struct srcu_struct *sp, unsigned long delay);
static void process_srcu(struct work_struct *work);
/* Wrappers for lock acquisition and release, see raw_spin_lock_rcu_node(). */
#define spin_lock_rcu_node(p) \
do { \
spin_lock(&ACCESS_PRIVATE(p, lock)); \
smp_mb__after_unlock_lock(); \
} while (0)
#define spin_unlock_rcu_node(p) spin_unlock(&ACCESS_PRIVATE(p, lock))
#define spin_lock_irq_rcu_node(p) \
do { \
spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \
smp_mb__after_unlock_lock(); \
} while (0)
#define spin_unlock_irq_rcu_node(p) \
spin_unlock_irq(&ACCESS_PRIVATE(p, lock))
#define spin_lock_irqsave_rcu_node(p, flags) \
do { \
spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
smp_mb__after_unlock_lock(); \
} while (0)
#define spin_unlock_irqrestore_rcu_node(p, flags) \
spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags) \
/*
* Initialize SRCU combining tree. Note that statically allocated
* srcu_struct structures might already have srcu_read_lock() and
@@ -77,7 +104,7 @@ static void init_srcu_struct_nodes(struct srcu_struct *sp, bool is_static)
/* Each pass through this loop initializes one srcu_node structure. */
rcu_for_each_node_breadth_first(sp, snp) {
raw_spin_lock_init(&ACCESS_PRIVATE(snp, lock));
spin_lock_init(&ACCESS_PRIVATE(snp, lock));
WARN_ON_ONCE(ARRAY_SIZE(snp->srcu_have_cbs) !=
ARRAY_SIZE(snp->srcu_data_have_cbs));
for (i = 0; i < ARRAY_SIZE(snp->srcu_have_cbs); i++) {
@@ -111,7 +138,7 @@ static void init_srcu_struct_nodes(struct srcu_struct *sp, bool is_static)
snp_first = sp->level[level];
for_each_possible_cpu(cpu) {
sdp = per_cpu_ptr(sp->sda, cpu);
raw_spin_lock_init(&ACCESS_PRIVATE(sdp, lock));
spin_lock_init(&ACCESS_PRIVATE(sdp, lock));
rcu_segcblist_init(&sdp->srcu_cblist);
sdp->srcu_cblist_invoking = false;
sdp->srcu_gp_seq_needed = sp->srcu_gp_seq;
@@ -170,7 +197,7 @@ int __init_srcu_struct(struct srcu_struct *sp, const char *name,
/* Don't re-initialize a lock while it is held. */
debug_check_no_locks_freed((void *)sp, sizeof(*sp));
lockdep_init_map(&sp->dep_map, name, key, 0);
raw_spin_lock_init(&ACCESS_PRIVATE(sp, lock));
spin_lock_init(&ACCESS_PRIVATE(sp, lock));
return init_srcu_struct_fields(sp, false);
}
EXPORT_SYMBOL_GPL(__init_srcu_struct);
@@ -187,7 +214,7 @@ EXPORT_SYMBOL_GPL(__init_srcu_struct);
*/
int init_srcu_struct(struct srcu_struct *sp)
{
raw_spin_lock_init(&ACCESS_PRIVATE(sp, lock));
spin_lock_init(&ACCESS_PRIVATE(sp, lock));
return init_srcu_struct_fields(sp, false);
}
EXPORT_SYMBOL_GPL(init_srcu_struct);
@@ -210,13 +237,13 @@ static void check_init_srcu_struct(struct srcu_struct *sp)
/* The smp_load_acquire() pairs with the smp_store_release(). */
if (!rcu_seq_state(smp_load_acquire(&sp->srcu_gp_seq_needed))) /*^^^*/
return; /* Already initialized. */
raw_spin_lock_irqsave_rcu_node(sp, flags);
spin_lock_irqsave_rcu_node(sp, flags);
if (!rcu_seq_state(sp->srcu_gp_seq_needed)) {
raw_spin_unlock_irqrestore_rcu_node(sp, flags);
spin_unlock_irqrestore_rcu_node(sp, flags);
return;
}
init_srcu_struct_fields(sp, true);
raw_spin_unlock_irqrestore_rcu_node(sp, flags);
spin_unlock_irqrestore_rcu_node(sp, flags);
}
/*
@@ -513,7 +540,7 @@ static void srcu_gp_end(struct srcu_struct *sp)
mutex_lock(&sp->srcu_cb_mutex);
/* End the current grace period. */
raw_spin_lock_irq_rcu_node(sp);
spin_lock_irq_rcu_node(sp);
idx = rcu_seq_state(sp->srcu_gp_seq);
WARN_ON_ONCE(idx != SRCU_STATE_SCAN2);
cbdelay = srcu_get_delay(sp);
@@ -522,7 +549,7 @@ static void srcu_gp_end(struct srcu_struct *sp)
gpseq = rcu_seq_current(&sp->srcu_gp_seq);
if (ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, gpseq))
sp->srcu_gp_seq_needed_exp = gpseq;
raw_spin_unlock_irq_rcu_node(sp);
spin_unlock_irq_rcu_node(sp);
mutex_unlock(&sp->srcu_gp_mutex);
/* A new grace period can start at this point. But only one. */
@@ -530,7 +557,7 @@ static void srcu_gp_end(struct srcu_struct *sp)
idx = rcu_seq_ctr(gpseq) % ARRAY_SIZE(snp->srcu_have_cbs);
idxnext = (idx + 1) % ARRAY_SIZE(snp->srcu_have_cbs);
rcu_for_each_node_breadth_first(sp, snp) {
raw_spin_lock_irq_rcu_node(snp);
spin_lock_irq_rcu_node(snp);
cbs = false;
if (snp >= sp->level[rcu_num_lvls - 1])
cbs = snp->srcu_have_cbs[idx] == gpseq;
@@ -540,7 +567,7 @@ static void srcu_gp_end(struct srcu_struct *sp)
snp->srcu_gp_seq_needed_exp = gpseq;
mask = snp->srcu_data_have_cbs[idx];
snp->srcu_data_have_cbs[idx] = 0;
raw_spin_unlock_irq_rcu_node(snp);
spin_unlock_irq_rcu_node(snp);
if (cbs)
srcu_schedule_cbs_snp(sp, snp, mask, cbdelay);
@@ -548,11 +575,11 @@ static void srcu_gp_end(struct srcu_struct *sp)
if (!(gpseq & counter_wrap_check))
for (cpu = snp->grplo; cpu <= snp->grphi; cpu++) {
sdp = per_cpu_ptr(sp->sda, cpu);
raw_spin_lock_irqsave_rcu_node(sdp, flags);
spin_lock_irqsave_rcu_node(sdp, flags);
if (ULONG_CMP_GE(gpseq,
sdp->srcu_gp_seq_needed + 100))
sdp->srcu_gp_seq_needed = gpseq;
raw_spin_unlock_irqrestore_rcu_node(sdp, flags);
spin_unlock_irqrestore_rcu_node(sdp, flags);
}
}
@@ -560,17 +587,17 @@ static void srcu_gp_end(struct srcu_struct *sp)
mutex_unlock(&sp->srcu_cb_mutex);
/* Start a new grace period if needed. */
raw_spin_lock_irq_rcu_node(sp);
spin_lock_irq_rcu_node(sp);
gpseq = rcu_seq_current(&sp->srcu_gp_seq);
if (!rcu_seq_state(gpseq) &&
ULONG_CMP_LT(gpseq, sp->srcu_gp_seq_needed)) {
srcu_gp_start(sp);
raw_spin_unlock_irq_rcu_node(sp);
spin_unlock_irq_rcu_node(sp);
/* Throttle expedited grace periods: Should be rare! */
srcu_reschedule(sp, rcu_seq_ctr(gpseq) & 0x3ff
? 0 : SRCU_INTERVAL);
} else {
raw_spin_unlock_irq_rcu_node(sp);
spin_unlock_irq_rcu_node(sp);
}
}
@@ -590,18 +617,18 @@ static void srcu_funnel_exp_start(struct srcu_struct *sp, struct srcu_node *snp,
if (rcu_seq_done(&sp->srcu_gp_seq, s) ||
ULONG_CMP_GE(READ_ONCE(snp->srcu_gp_seq_needed_exp), s))
return;
raw_spin_lock_irqsave_rcu_node(snp, flags);
spin_lock_irqsave_rcu_node(snp, flags);
if (ULONG_CMP_GE(snp->srcu_gp_seq_needed_exp, s)) {
raw_spin_unlock_irqrestore_rcu_node(snp, flags);
spin_unlock_irqrestore_rcu_node(snp, flags);
return;
}
WRITE_ONCE(snp->srcu_gp_seq_needed_exp, s);
raw_spin_unlock_irqrestore_rcu_node(snp, flags);
spin_unlock_irqrestore_rcu_node(snp, flags);
}
raw_spin_lock_irqsave_rcu_node(sp, flags);
spin_lock_irqsave_rcu_node(sp, flags);
if (!ULONG_CMP_LT(sp->srcu_gp_seq_needed_exp, s))
sp->srcu_gp_seq_needed_exp = s;
raw_spin_unlock_irqrestore_rcu_node(sp, flags);
spin_unlock_irqrestore_rcu_node(sp, flags);
}
/*
@@ -623,12 +650,12 @@ static void srcu_funnel_gp_start(struct srcu_struct *sp, struct srcu_data *sdp,
for (; snp != NULL; snp = snp->srcu_parent) {
if (rcu_seq_done(&sp->srcu_gp_seq, s) && snp != sdp->mynode)
return; /* GP already done and CBs recorded. */
raw_spin_lock_irqsave_rcu_node(snp, flags);
spin_lock_irqsave_rcu_node(snp, flags);
if (ULONG_CMP_GE(snp->srcu_have_cbs[idx], s)) {
snp_seq = snp->srcu_have_cbs[idx];
if (snp == sdp->mynode && snp_seq == s)
snp->srcu_data_have_cbs[idx] |= sdp->grpmask;
raw_spin_unlock_irqrestore_rcu_node(snp, flags);
spin_unlock_irqrestore_rcu_node(snp, flags);
if (snp == sdp->mynode && snp_seq != s) {
srcu_schedule_cbs_sdp(sdp, do_norm
? SRCU_INTERVAL
@@ -644,11 +671,11 @@ static void srcu_funnel_gp_start(struct srcu_struct *sp, struct srcu_data *sdp,
snp->srcu_data_have_cbs[idx] |= sdp->grpmask;
if (!do_norm && ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, s))
snp->srcu_gp_seq_needed_exp = s;
raw_spin_unlock_irqrestore_rcu_node(snp, flags);
spin_unlock_irqrestore_rcu_node(snp, flags);
}
/* Top of tree, must ensure the grace period will be started. */
raw_spin_lock_irqsave_rcu_node(sp, flags);
spin_lock_irqsave_rcu_node(sp, flags);
if (ULONG_CMP_LT(sp->srcu_gp_seq_needed, s)) {
/*
* Record need for grace period s. Pair with load
@@ -667,7 +694,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *sp, struct srcu_data *sdp,
queue_delayed_work(system_power_efficient_wq, &sp->work,
srcu_get_delay(sp));
}
raw_spin_unlock_irqrestore_rcu_node(sp, flags);
spin_unlock_irqrestore_rcu_node(sp, flags);
}
/*
@@ -830,7 +857,7 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp,
rhp->func = func;
local_irq_save(flags);
sdp = this_cpu_ptr(sp->sda);
raw_spin_lock_rcu_node(sdp);
spin_lock_rcu_node(sdp);
rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp, false);
rcu_segcblist_advance(&sdp->srcu_cblist,
rcu_seq_current(&sp->srcu_gp_seq));
@@ -844,7 +871,7 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp,
sdp->srcu_gp_seq_needed_exp = s;
needexp = true;
}
raw_spin_unlock_irqrestore_rcu_node(sdp, flags);
spin_unlock_irqrestore_rcu_node(sdp, flags);
if (needgp)
srcu_funnel_gp_start(sp, sdp, s, do_norm);
else if (needexp)
@@ -900,7 +927,7 @@ static void __synchronize_srcu(struct srcu_struct *sp, bool do_norm)
/*
* Make sure that later code is ordered after the SRCU grace
* period. This pairs with the raw_spin_lock_irq_rcu_node()
* period. This pairs with the spin_lock_irq_rcu_node()
* in srcu_invoke_callbacks(). Unlike Tree RCU, this is needed
* because the current CPU might have been totally uninvolved with
* (and thus unordered against) that grace period.
@@ -1024,7 +1051,7 @@ void srcu_barrier(struct srcu_struct *sp)
*/
for_each_possible_cpu(cpu) {
sdp = per_cpu_ptr(sp->sda, cpu);
raw_spin_lock_irq_rcu_node(sdp);
spin_lock_irq_rcu_node(sdp);
atomic_inc(&sp->srcu_barrier_cpu_cnt);
sdp->srcu_barrier_head.func = srcu_barrier_cb;
debug_rcu_head_queue(&sdp->srcu_barrier_head);
@@ -1033,7 +1060,7 @@ void srcu_barrier(struct srcu_struct *sp)
debug_rcu_head_unqueue(&sdp->srcu_barrier_head);
atomic_dec(&sp->srcu_barrier_cpu_cnt);
}
raw_spin_unlock_irq_rcu_node(sdp);
spin_unlock_irq_rcu_node(sdp);
}
/* Remove the initial count, at which point reaching zero can happen. */
@@ -1082,17 +1109,17 @@ static void srcu_advance_state(struct srcu_struct *sp)
*/
idx = rcu_seq_state(smp_load_acquire(&sp->srcu_gp_seq)); /* ^^^ */
if (idx == SRCU_STATE_IDLE) {
raw_spin_lock_irq_rcu_node(sp);
spin_lock_irq_rcu_node(sp);
if (ULONG_CMP_GE(sp->srcu_gp_seq, sp->srcu_gp_seq_needed)) {
WARN_ON_ONCE(rcu_seq_state(sp->srcu_gp_seq));
raw_spin_unlock_irq_rcu_node(sp);
spin_unlock_irq_rcu_node(sp);
mutex_unlock(&sp->srcu_gp_mutex);
return;
}
idx = rcu_seq_state(READ_ONCE(sp->srcu_gp_seq));
if (idx == SRCU_STATE_IDLE)
srcu_gp_start(sp);
raw_spin_unlock_irq_rcu_node(sp);
spin_unlock_irq_rcu_node(sp);
if (idx != SRCU_STATE_IDLE) {
mutex_unlock(&sp->srcu_gp_mutex);
return; /* Someone else started the grace period. */
@@ -1141,19 +1168,19 @@ static void srcu_invoke_callbacks(struct work_struct *work)
sdp = container_of(work, struct srcu_data, work.work);
sp = sdp->sp;
rcu_cblist_init(&ready_cbs);
raw_spin_lock_irq_rcu_node(sdp);
spin_lock_irq_rcu_node(sdp);
rcu_segcblist_advance(&sdp->srcu_cblist,
rcu_seq_current(&sp->srcu_gp_seq));
if (sdp->srcu_cblist_invoking ||
!rcu_segcblist_ready_cbs(&sdp->srcu_cblist)) {
raw_spin_unlock_irq_rcu_node(sdp);
spin_unlock_irq_rcu_node(sdp);
return; /* Someone else on the job or nothing to do. */
}
/* We are on the job! Extract and invoke ready callbacks. */
sdp->srcu_cblist_invoking = true;
rcu_segcblist_extract_done_cbs(&sdp->srcu_cblist, &ready_cbs);
raw_spin_unlock_irq_rcu_node(sdp);
spin_unlock_irq_rcu_node(sdp);
rhp = rcu_cblist_dequeue(&ready_cbs);
for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) {
debug_rcu_head_unqueue(rhp);
@@ -1166,13 +1193,13 @@ static void srcu_invoke_callbacks(struct work_struct *work)
* Update counts, accelerate new callbacks, and if needed,
* schedule another round of callback invocation.
*/
raw_spin_lock_irq_rcu_node(sdp);
spin_lock_irq_rcu_node(sdp);
rcu_segcblist_insert_count(&sdp->srcu_cblist, &ready_cbs);
(void)rcu_segcblist_accelerate(&sdp->srcu_cblist,
rcu_seq_snap(&sp->srcu_gp_seq));
sdp->srcu_cblist_invoking = false;
more = rcu_segcblist_ready_cbs(&sdp->srcu_cblist);
raw_spin_unlock_irq_rcu_node(sdp);
spin_unlock_irq_rcu_node(sdp);
if (more)
srcu_schedule_cbs_sdp(sdp, 0);
}
@@ -1185,7 +1212,7 @@ static void srcu_reschedule(struct srcu_struct *sp, unsigned long delay)
{
bool pushgp = true;
raw_spin_lock_irq_rcu_node(sp);
spin_lock_irq_rcu_node(sp);
if (ULONG_CMP_GE(sp->srcu_gp_seq, sp->srcu_gp_seq_needed)) {
if (!WARN_ON_ONCE(rcu_seq_state(sp->srcu_gp_seq))) {
/* All requests fulfilled, time to go idle. */
@@ -1195,7 +1222,7 @@ static void srcu_reschedule(struct srcu_struct *sp, unsigned long delay)
/* Outstanding request and no GP. Start one. */
srcu_gp_start(sp);
}
raw_spin_unlock_irq_rcu_node(sp);
spin_unlock_irq_rcu_node(sp);
if (pushgp)
queue_delayed_work(system_power_efficient_wq, &sp->work, delay);

355
kernel/rcu/tree.c
View File

@@ -265,24 +265,11 @@ void rcu_bh_qs(void)
#endif
static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
.dynticks_nesting = DYNTICK_TASK_EXIT_IDLE,
.dynticks_nesting = 1,
.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
};
/*
* There's a few places, currently just in the tracing infrastructure,
* that uses rcu_irq_enter() to make sure RCU is watching. But there's
* a small location where that will not even work. In those cases
* rcu_irq_enter_disabled() needs to be checked to make sure rcu_irq_enter()
* can be called.
*/
static DEFINE_PER_CPU(bool, disable_rcu_irq_enter);
bool rcu_irq_enter_disabled(void)
{
return this_cpu_read(disable_rcu_irq_enter);
}
/*
* Record entry into an extended quiescent state. This is only to be
* called when not already in an extended quiescent state.
@@ -762,68 +749,39 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
}
/*
* rcu_eqs_enter_common - current CPU is entering an extended quiescent state
* Enter an RCU extended quiescent state, which can be either the
* idle loop or adaptive-tickless usermode execution.
*
* Enter idle, doing appropriate accounting. The caller must have
* disabled interrupts.
* We crowbar the ->dynticks_nmi_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.
*/
static void rcu_eqs_enter_common(bool user)
static void rcu_eqs_enter(bool user)
{
struct rcu_state *rsp;
struct rcu_data *rdp;
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
struct rcu_dynticks *rdtp;
rdtp = this_cpu_ptr(&rcu_dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
rdtp->dynticks_nesting == 0);
if (rdtp->dynticks_nesting != 1) {
rdtp->dynticks_nesting--;
return;
}
lockdep_assert_irqs_disabled();
trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!user && !is_idle_task(current)) {
struct task_struct *idle __maybe_unused =
idle_task(smp_processor_id());
trace_rcu_dyntick(TPS("Error on entry: not idle task"), rdtp->dynticks_nesting, 0);
rcu_ftrace_dump(DUMP_ORIG);
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
current->pid, current->comm,
idle->pid, idle->comm); /* must be idle task! */
}
trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
for_each_rcu_flavor(rsp) {
rdp = this_cpu_ptr(rsp->rda);
do_nocb_deferred_wakeup(rdp);
}
rcu_prepare_for_idle();
__this_cpu_inc(disable_rcu_irq_enter);
rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
__this_cpu_dec(disable_rcu_irq_enter);
WRITE_ONCE(rdtp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
rcu_dynticks_eqs_enter();
rcu_dynticks_task_enter();
/*
* It is illegal to enter an extended quiescent state while
* in an RCU read-side critical section.
*/
RCU_LOCKDEP_WARN(lock_is_held(&rcu_lock_map),
"Illegal idle entry in RCU read-side critical section.");
RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map),
"Illegal idle entry in RCU-bh read-side critical section.");
RCU_LOCKDEP_WARN(lock_is_held(&rcu_sched_lock_map),
"Illegal idle entry in RCU-sched read-side critical section.");
}
/*
* Enter an RCU extended quiescent state, which can be either the
* idle loop or adaptive-tickless usermode execution.
*/
static void rcu_eqs_enter(bool user)
{
struct rcu_dynticks *rdtp;
rdtp = this_cpu_ptr(&rcu_dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
(rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE)
rcu_eqs_enter_common(user);
else
rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
}
/**
@@ -834,10 +792,6 @@ static void rcu_eqs_enter(bool user)
* critical sections can occur in irq handlers in idle, a possibility
* handled by irq_enter() and irq_exit().)
*
* 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.
*/
@@ -866,6 +820,46 @@ void rcu_user_enter(void)
}
#endif /* CONFIG_NO_HZ_FULL */
/**
* rcu_nmi_exit - inform RCU of exit from NMI context
*
* If we are returning from the outermost NMI handler that interrupted an
* 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)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
/*
* Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
* (We are exiting an NMI handler, so RCU better be paying attention
* to us!)
*/
WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
/*
* If the nesting level is not 1, the CPU wasn't RCU-idle, so
* leave it in non-RCU-idle state.
*/
if (rdtp->dynticks_nmi_nesting != 1) {
trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, rdtp->dynticks_nmi_nesting - 2, rdtp->dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
rdtp->dynticks_nmi_nesting - 2);
return;
}
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0, rdtp->dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
rcu_dynticks_eqs_enter();
}
/**
* rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
*
@@ -875,8 +869,8 @@ void rcu_user_enter(void)
*
* This code assumes that the idle loop never does anything that might
* result in unbalanced calls to irq_enter() and irq_exit(). If your
* architecture violates this assumption, RCU will give you what you
* deserve, good and hard. But very infrequently and irreproducibly.
* architecture's idle loop violates this assumption, RCU will give you what
* you deserve, good and hard. But very infrequently and irreproducibly.
*
* Use things like work queues to work around this limitation.
*
@@ -887,23 +881,14 @@ void rcu_user_enter(void)
*/
void rcu_irq_exit(void)
{
struct rcu_dynticks *rdtp;
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
lockdep_assert_irqs_disabled();
rdtp = this_cpu_ptr(&rcu_dynticks);
/* Page faults can happen in NMI handlers, so check... */
if (rdtp->dynticks_nmi_nesting)
return;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
rdtp->dynticks_nesting < 1);
if (rdtp->dynticks_nesting <= 1) {
rcu_eqs_enter_common(true);
} else {
trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nesting, rdtp->dynticks_nesting - 1);
rdtp->dynticks_nesting--;
}
if (rdtp->dynticks_nmi_nesting == 1)
rcu_prepare_for_idle();
rcu_nmi_exit();
if (rdtp->dynticks_nmi_nesting == 0)
rcu_dynticks_task_enter();
}
/*
@@ -921,56 +906,34 @@ void rcu_irq_exit_irqson(void)
local_irq_restore(flags);
}
/*
* rcu_eqs_exit_common - current CPU moving away from extended quiescent state
*
* If the new value of the ->dynticks_nesting counter was previously zero,
* we really have exited idle, and must do the appropriate accounting.
* The caller must have disabled interrupts.
*/
static void rcu_eqs_exit_common(long long oldval, int user)
{
RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);)
rcu_dynticks_task_exit();
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!user && !is_idle_task(current)) {
struct task_struct *idle __maybe_unused =
idle_task(smp_processor_id());
trace_rcu_dyntick(TPS("Error on exit: not idle task"),
oldval, rdtp->dynticks_nesting);
rcu_ftrace_dump(DUMP_ORIG);
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
current->pid, current->comm,
idle->pid, idle->comm); /* must be idle task! */
}
}
/*
* Exit an RCU extended quiescent state, which can be either the
* idle loop or adaptive-tickless usermode execution.
*
* We crowbar the ->dynticks_nmi_nesting field to DYNTICK_IRQ_NONIDLE to
* allow for the possibility of usermode upcalls messing up our count of
* interrupt nesting level during the busy period that is just now starting.
*/
static void rcu_eqs_exit(bool user)
{
struct rcu_dynticks *rdtp;
long long oldval;
long oldval;
lockdep_assert_irqs_disabled();
rdtp = this_cpu_ptr(&rcu_dynticks);
oldval = rdtp->dynticks_nesting;
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 {
__this_cpu_inc(disable_rcu_irq_enter);
rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
rcu_eqs_exit_common(oldval, user);
__this_cpu_dec(disable_rcu_irq_enter);
if (oldval) {
rdtp->dynticks_nesting++;
return;
}
rcu_dynticks_task_exit();
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, 1, rdtp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
WRITE_ONCE(rdtp->dynticks_nesting, 1);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
}
/**
@@ -979,11 +942,6 @@ static void rcu_eqs_exit(bool user)
* Exit idle mode, in other words, -enter- the mode in which RCU
* read-side critical sections can occur.
*
* We crowbar the ->dynticks_nesting field to DYNTICK_TASK_NEST to
* 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.
*/
@@ -1012,65 +970,6 @@ void rcu_user_exit(void)
}
#endif /* CONFIG_NO_HZ_FULL */
/**
* rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
*
* Enter an interrupt handler, which might possibly result in exiting
* idle mode, in other words, entering the mode in which read-side critical
* sections can occur. The caller must have disabled interrupts.
*
* Note that the Linux kernel is fully capable of entering an interrupt
* handler that it never exits, for example when doing upcalls to
* user mode! This code assumes that the idle loop never does upcalls to
* user mode. If your architecture does do upcalls from the idle loop (or
* does anything else that results in unbalanced calls to the irq_enter()
* and irq_exit() functions), RCU will give you what you deserve, good
* and hard. But very infrequently and irreproducibly.
*
* 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)
{
struct rcu_dynticks *rdtp;
long long oldval;
lockdep_assert_irqs_disabled();
rdtp = this_cpu_ptr(&rcu_dynticks);
/* Page faults can happen in NMI handlers, so check... */
if (rdtp->dynticks_nmi_nesting)
return;
oldval = rdtp->dynticks_nesting;
rdtp->dynticks_nesting++;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
rdtp->dynticks_nesting == 0);
if (oldval)
trace_rcu_dyntick(TPS("++="), oldval, rdtp->dynticks_nesting);
else
rcu_eqs_exit_common(oldval, true);
}
/*
* 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)
{
unsigned long flags;
local_irq_save(flags);
rcu_irq_enter();
local_irq_restore(flags);
}
/**
* rcu_nmi_enter - inform RCU of entry to NMI context
*
@@ -1086,7 +985,7 @@ void rcu_irq_enter_irqson(void)
void rcu_nmi_enter(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
int incby = 2;
long incby = 2;
/* Complain about underflow. */
WARN_ON_ONCE(rdtp->dynticks_nmi_nesting < 0);
@@ -1103,45 +1002,61 @@ void rcu_nmi_enter(void)
rcu_dynticks_eqs_exit();
incby = 1;
}
rdtp->dynticks_nmi_nesting += incby;
trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
rdtp->dynticks_nmi_nesting,
rdtp->dynticks_nmi_nesting + incby, rdtp->dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
rdtp->dynticks_nmi_nesting + incby);
barrier();
}
/**
* rcu_nmi_exit - inform RCU of exit from NMI context
* rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
*
* If we are returning from the outermost NMI handler that interrupted an
* 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.
* Enter an interrupt handler, which might possibly result in exiting
* idle mode, in other words, entering the mode in which read-side critical
* sections can occur. The caller must have disabled interrupts.
*
* If you add or remove a call to rcu_nmi_exit(), be sure to test
* with CONFIG_RCU_EQS_DEBUG=y.
* Note that the Linux kernel is fully capable of entering an interrupt
* handler that it never exits, for example when doing upcalls to user mode!
* This code assumes that the idle loop never does upcalls to user mode.
* If your architecture's idle loop does do upcalls to user mode (or does
* anything else that results in unbalanced calls to the irq_enter() and
* irq_exit() functions), RCU will give you what you deserve, good and hard.
* But very infrequently and irreproducibly.
*
* 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_nmi_exit(void)
void rcu_irq_enter(void)
{
struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
/*
* Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
* (We are exiting an NMI handler, so RCU better be paying attention
* to us!)
*/
WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
lockdep_assert_irqs_disabled();
if (rdtp->dynticks_nmi_nesting == 0)
rcu_dynticks_task_exit();
rcu_nmi_enter();
if (rdtp->dynticks_nmi_nesting == 1)
rcu_cleanup_after_idle();
}
/*
* If the nesting level is not 1, the CPU wasn't RCU-idle, so
* leave it in non-RCU-idle state.
*/
if (rdtp->dynticks_nmi_nesting != 1) {
rdtp->dynticks_nmi_nesting -= 2;
return;
}
/*
* 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)
{
unsigned long flags;
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
rdtp->dynticks_nmi_nesting = 0;
rcu_dynticks_eqs_enter();
local_irq_save(flags);
rcu_irq_enter();
local_irq_restore(flags);
}
/**
@@ -1233,7 +1148,8 @@ EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online);
*/
static int rcu_is_cpu_rrupt_from_idle(void)
{
return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 1;
return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 0 &&
__this_cpu_read(rcu_dynticks.dynticks_nmi_nesting) <= 1;
}
/*
@@ -2789,6 +2705,11 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
rdp->n_force_qs_snap = rsp->n_force_qs;
} else if (count < rdp->qlen_last_fqs_check - qhimark)
rdp->qlen_last_fqs_check = count;
/*
* The following usually indicates a double call_rcu(). To track
* this down, try building with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.
*/
WARN_ON_ONCE(rcu_segcblist_empty(&rdp->cblist) != (count == 0));
local_irq_restore(flags);
@@ -3723,7 +3644,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
raw_spin_lock_irqsave_rcu_node(rnp, flags);
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1);
WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks)));
rdp->cpu = cpu;
rdp->rsp = rsp;
@@ -3752,7 +3673,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */
!init_nocb_callback_list(rdp))
rcu_segcblist_init(&rdp->cblist); /* Re-enable callbacks. */
rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
rdp->dynticks->dynticks_nesting = 1; /* CPU not up, no tearing. */
rcu_dynticks_eqs_online();
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */

5
kernel/rcu/tree.h
View File

@@ -38,9 +38,8 @@
* Dynticks per-CPU state.
*/
struct rcu_dynticks {
long long dynticks_nesting; /* Track irq/process nesting level. */
/* Process level is worth LLONG_MAX/2. */
int dynticks_nmi_nesting; /* Track NMI nesting level. */
long dynticks_nesting; /* Track process nesting level. */
long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */
atomic_t dynticks; /* Even value for idle, else odd. */
bool rcu_need_heavy_qs; /* GP old, need heavy quiescent state. */
unsigned long rcu_qs_ctr; /* Light universal quiescent state ctr. */

13
kernel/rcu/tree_plugin.h
View File

@@ -61,7 +61,6 @@ DEFINE_PER_CPU(char, rcu_cpu_has_work);
#ifdef CONFIG_RCU_NOCB_CPU
static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
static bool have_rcu_nocb_mask; /* Was rcu_nocb_mask allocated? */
static bool __read_mostly rcu_nocb_poll; /* Offload kthread are to poll. */
#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
@@ -1687,7 +1686,7 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
}
print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
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",
pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%ld/%ld softirq=%u/%u fqs=%ld %s\n",
cpu,
"O."[!!cpu_online(cpu)],
"o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
@@ -1752,7 +1751,6 @@ static void increment_cpu_stall_ticks(void)
static int __init rcu_nocb_setup(char *str)
{
alloc_bootmem_cpumask_var(&rcu_nocb_mask);
have_rcu_nocb_mask = true;
cpulist_parse(str, rcu_nocb_mask);
return 1;
}
@@ -1801,7 +1799,7 @@ static void rcu_init_one_nocb(struct rcu_node *rnp)
/* Is the specified CPU a no-CBs CPU? */
bool rcu_is_nocb_cpu(int cpu)
{
if (have_rcu_nocb_mask)
if (cpumask_available(rcu_nocb_mask))
return cpumask_test_cpu(cpu, rcu_nocb_mask);
return false;
}
@@ -2295,14 +2293,13 @@ void __init rcu_init_nohz(void)
need_rcu_nocb_mask = true;
#endif /* #if defined(CONFIG_NO_HZ_FULL) */
if (!have_rcu_nocb_mask && need_rcu_nocb_mask) {
if (!cpumask_available(rcu_nocb_mask) && need_rcu_nocb_mask) {
if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
pr_info("rcu_nocb_mask allocation failed, callback offloading disabled.\n");
return;
}
have_rcu_nocb_mask = true;
}
if (!have_rcu_nocb_mask)
if (!cpumask_available(rcu_nocb_mask))
return;
#if defined(CONFIG_NO_HZ_FULL)
@@ -2428,7 +2425,7 @@ static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp)
struct rcu_data *rdp_leader = NULL; /* Suppress misguided gcc warn. */
struct rcu_data *rdp_prev = NULL;
if (!have_rcu_nocb_mask)
if (!cpumask_available(rcu_nocb_mask))
return;
if (ls == -1) {
ls = int_sqrt(nr_cpu_ids);