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authorLinus Torvalds <torvalds@linux-foundation.org>2016-02-28 07:52:00 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-02-28 07:52:00 -0800
commit1b9540ce033ad15802e36ad1cd1c36bdad98eeea (patch)
tree4b6d5484b15a9a9ca8ff64f7444705600d0cbb68
parent4b696dcb1a55e40648ad0eec4af991c72f945a85 (diff)
parent0da4cf3e0a68c97ef811569804616a811f786729 (diff)
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Thomas Gleixner: "A rather largish series of 12 patches addressing a maze of race conditions in the perf core code from Peter Zijlstra" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Robustify task_function_call() perf: Fix scaling vs. perf_install_in_context() perf: Fix scaling vs. perf_event_enable() perf: Fix scaling vs. perf_event_enable_on_exec() perf: Fix ctx time tracking by introducing EVENT_TIME perf: Cure event->pending_disable race perf: Fix race between event install and jump_labels perf: Fix cloning perf: Only update context time when active perf: Allow perf_release() with !event->ctx perf: Do not double free perf: Close install vs. exit race
-rw-r--r--include/linux/perf_event.h7
-rw-r--r--kernel/events/core.c368
2 files changed, 244 insertions, 131 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b35a61a481fa..f5c5a3fa2c81 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -397,6 +397,7 @@ struct pmu {
* enum perf_event_active_state - the states of a event
*/
enum perf_event_active_state {
+ PERF_EVENT_STATE_DEAD = -4,
PERF_EVENT_STATE_EXIT = -3,
PERF_EVENT_STATE_ERROR = -2,
PERF_EVENT_STATE_OFF = -1,
@@ -905,7 +906,7 @@ perf_sw_event_sched(u32 event_id, u64 nr, u64 addr)
}
}
-extern struct static_key_deferred perf_sched_events;
+extern struct static_key_false perf_sched_events;
static __always_inline bool
perf_sw_migrate_enabled(void)
@@ -924,7 +925,7 @@ static inline void perf_event_task_migrate(struct task_struct *task)
static inline void perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task)
{
- if (static_key_false(&perf_sched_events.key))
+ if (static_branch_unlikely(&perf_sched_events))
__perf_event_task_sched_in(prev, task);
if (perf_sw_migrate_enabled() && task->sched_migrated) {
@@ -941,7 +942,7 @@ static inline void perf_event_task_sched_out(struct task_struct *prev,
{
perf_sw_event_sched(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 0);
- if (static_key_false(&perf_sched_events.key))
+ if (static_branch_unlikely(&perf_sched_events))
__perf_event_task_sched_out(prev, next);
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0d58522103cd..614614821f00 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -64,8 +64,17 @@ static void remote_function(void *data)
struct task_struct *p = tfc->p;
if (p) {
- tfc->ret = -EAGAIN;
- if (task_cpu(p) != smp_processor_id() || !task_curr(p))
+ /* -EAGAIN */
+ if (task_cpu(p) != smp_processor_id())
+ return;
+
+ /*
+ * Now that we're on right CPU with IRQs disabled, we can test
+ * if we hit the right task without races.
+ */
+
+ tfc->ret = -ESRCH; /* No such (running) process */
+ if (p != current)
return;
}
@@ -92,13 +101,17 @@ task_function_call(struct task_struct *p, remote_function_f func, void *info)
.p = p,
.func = func,
.info = info,
- .ret = -ESRCH, /* No such (running) process */
+ .ret = -EAGAIN,
};
+ int ret;
- if (task_curr(p))
- smp_call_function_single(task_cpu(p), remote_function, &data, 1);
+ do {
+ ret = smp_call_function_single(task_cpu(p), remote_function, &data, 1);
+ if (!ret)
+ ret = data.ret;
+ } while (ret == -EAGAIN);
- return data.ret;
+ return ret;
}
/**
@@ -169,19 +182,6 @@ static bool is_kernel_event(struct perf_event *event)
* rely on ctx->is_active and therefore cannot use event_function_call().
* See perf_install_in_context().
*
- * This is because we need a ctx->lock serialized variable (ctx->is_active)
- * to reliably determine if a particular task/context is scheduled in. The
- * task_curr() use in task_function_call() is racy in that a remote context
- * switch is not a single atomic operation.
- *
- * As is, the situation is 'safe' because we set rq->curr before we do the
- * actual context switch. This means that task_curr() will fail early, but
- * we'll continue spinning on ctx->is_active until we've passed
- * perf_event_task_sched_out().
- *
- * Without this ctx->lock serialized variable we could have race where we find
- * the task (and hence the context) would not be active while in fact they are.
- *
* If ctx->nr_events, then ctx->is_active and cpuctx->task_ctx are set.
*/
@@ -212,7 +212,7 @@ static int event_function(void *info)
*/
if (ctx->task) {
if (ctx->task != current) {
- ret = -EAGAIN;
+ ret = -ESRCH;
goto unlock;
}
@@ -276,10 +276,10 @@ static void event_function_call(struct perf_event *event, event_f func, void *da
return;
}
-again:
if (task == TASK_TOMBSTONE)
return;
+again:
if (!task_function_call(task, event_function, &efs))
return;
@@ -289,13 +289,15 @@ again:
* a concurrent perf_event_context_sched_out().
*/
task = ctx->task;
- if (task != TASK_TOMBSTONE) {
- if (ctx->is_active) {
- raw_spin_unlock_irq(&ctx->lock);
- goto again;
- }
- func(event, NULL, ctx, data);
+ if (task == TASK_TOMBSTONE) {
+ raw_spin_unlock_irq(&ctx->lock);
+ return;
}
+ if (ctx->is_active) {
+ raw_spin_unlock_irq(&ctx->lock);
+ goto again;
+ }
+ func(event, NULL, ctx, data);
raw_spin_unlock_irq(&ctx->lock);
}
@@ -314,6 +316,7 @@ again:
enum event_type_t {
EVENT_FLEXIBLE = 0x1,
EVENT_PINNED = 0x2,
+ EVENT_TIME = 0x4,
EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
};
@@ -321,7 +324,13 @@ enum event_type_t {
* perf_sched_events : >0 events exist
* perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
*/
-struct static_key_deferred perf_sched_events __read_mostly;
+
+static void perf_sched_delayed(struct work_struct *work);
+DEFINE_STATIC_KEY_FALSE(perf_sched_events);
+static DECLARE_DELAYED_WORK(perf_sched_work, perf_sched_delayed);
+static DEFINE_MUTEX(perf_sched_mutex);
+static atomic_t perf_sched_count;
+
static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
static DEFINE_PER_CPU(int, perf_sched_cb_usages);
@@ -1288,16 +1297,18 @@ static u64 perf_event_time(struct perf_event *event)
/*
* Update the total_time_enabled and total_time_running fields for a event.
- * The caller of this function needs to hold the ctx->lock.
*/
static void update_event_times(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
u64 run_end;
+ lockdep_assert_held(&ctx->lock);
+
if (event->state < PERF_EVENT_STATE_INACTIVE ||
event->group_leader->state < PERF_EVENT_STATE_INACTIVE)
return;
+
/*
* in cgroup mode, time_enabled represents
* the time the event was enabled AND active
@@ -1645,7 +1656,7 @@ out:
static bool is_orphaned_event(struct perf_event *event)
{
- return event->state == PERF_EVENT_STATE_EXIT;
+ return event->state == PERF_EVENT_STATE_DEAD;
}
static inline int pmu_filter_match(struct perf_event *event)
@@ -1690,14 +1701,14 @@ event_sched_out(struct perf_event *event,
perf_pmu_disable(event->pmu);
+ event->tstamp_stopped = tstamp;
+ event->pmu->del(event, 0);
+ event->oncpu = -1;
event->state = PERF_EVENT_STATE_INACTIVE;
if (event->pending_disable) {
event->pending_disable = 0;
event->state = PERF_EVENT_STATE_OFF;
}
- event->tstamp_stopped = tstamp;
- event->pmu->del(event, 0);
- event->oncpu = -1;
if (!is_software_event(event))
cpuctx->active_oncpu--;
@@ -1732,7 +1743,6 @@ group_sched_out(struct perf_event *group_event,
}
#define DETACH_GROUP 0x01UL
-#define DETACH_STATE 0x02UL
/*
* Cross CPU call to remove a performance event
@@ -1752,8 +1762,6 @@ __perf_remove_from_context(struct perf_event *event,
if (flags & DETACH_GROUP)
perf_group_detach(event);
list_del_event(event, ctx);
- if (flags & DETACH_STATE)
- event->state = PERF_EVENT_STATE_EXIT;
if (!ctx->nr_events && ctx->is_active) {
ctx->is_active = 0;
@@ -2063,14 +2071,27 @@ static void add_event_to_ctx(struct perf_event *event,
event->tstamp_stopped = tstamp;
}
-static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx);
+static void ctx_sched_out(struct perf_event_context *ctx,
+ struct perf_cpu_context *cpuctx,
+ enum event_type_t event_type);
static void
ctx_sched_in(struct perf_event_context *ctx,
struct perf_cpu_context *cpuctx,
enum event_type_t event_type,
struct task_struct *task);
+static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
+ struct perf_event_context *ctx)
+{
+ if (!cpuctx->task_ctx)
+ return;
+
+ if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
+ return;
+
+ ctx_sched_out(ctx, cpuctx, EVENT_ALL);
+}
+
static void perf_event_sched_in(struct perf_cpu_context *cpuctx,
struct perf_event_context *ctx,
struct task_struct *task)
@@ -2097,49 +2118,68 @@ static void ctx_resched(struct perf_cpu_context *cpuctx,
/*
* Cross CPU call to install and enable a performance event
*
- * Must be called with ctx->mutex held
+ * Very similar to remote_function() + event_function() but cannot assume that
+ * things like ctx->is_active and cpuctx->task_ctx are set.
*/
static int __perf_install_in_context(void *info)
{
- struct perf_event_context *ctx = info;
+ struct perf_event *event = info;
+ struct perf_event_context *ctx = event->ctx;
struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
struct perf_event_context *task_ctx = cpuctx->task_ctx;
+ bool activate = true;
+ int ret = 0;
raw_spin_lock(&cpuctx->ctx.lock);
if (ctx->task) {
raw_spin_lock(&ctx->lock);
- /*
- * If we hit the 'wrong' task, we've since scheduled and
- * everything should be sorted, nothing to do!
- */
task_ctx = ctx;
- if (ctx->task != current)
+
+ /* If we're on the wrong CPU, try again */
+ if (task_cpu(ctx->task) != smp_processor_id()) {
+ ret = -ESRCH;
goto unlock;
+ }
/*
- * If task_ctx is set, it had better be to us.
+ * If we're on the right CPU, see if the task we target is
+ * current, if not we don't have to activate the ctx, a future
+ * context switch will do that for us.
*/
- WARN_ON_ONCE(cpuctx->task_ctx != ctx && cpuctx->task_ctx);
+ if (ctx->task != current)
+ activate = false;
+ else
+ WARN_ON_ONCE(cpuctx->task_ctx && cpuctx->task_ctx != ctx);
+
} else if (task_ctx) {
raw_spin_lock(&task_ctx->lock);
}
- ctx_resched(cpuctx, task_ctx);
+ if (activate) {
+ ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+ add_event_to_ctx(event, ctx);
+ ctx_resched(cpuctx, task_ctx);
+ } else {
+ add_event_to_ctx(event, ctx);
+ }
+
unlock:
perf_ctx_unlock(cpuctx, task_ctx);
- return 0;
+ return ret;
}
/*
- * Attach a performance event to a context
+ * Attach a performance event to a context.
+ *
+ * Very similar to event_function_call, see comment there.
*/
static void
perf_install_in_context(struct perf_event_context *ctx,
struct perf_event *event,
int cpu)
{
- struct task_struct *task = NULL;
+ struct task_struct *task = READ_ONCE(ctx->task);
lockdep_assert_held(&ctx->mutex);
@@ -2147,40 +2187,46 @@ perf_install_in_context(struct perf_event_context *ctx,
if (event->cpu != -1)
event->cpu = cpu;
+ if (!task) {
+ cpu_function_call(cpu, __perf_install_in_context, event);
+ return;
+ }
+
+ /*
+ * Should not happen, we validate the ctx is still alive before calling.
+ */
+ if (WARN_ON_ONCE(task == TASK_TOMBSTONE))
+ return;
+
/*
* Installing events is tricky because we cannot rely on ctx->is_active
* to be set in case this is the nr_events 0 -> 1 transition.
- *
- * So what we do is we add the event to the list here, which will allow
- * a future context switch to DTRT and then send a racy IPI. If the IPI
- * fails to hit the right task, this means a context switch must have
- * happened and that will have taken care of business.
*/
- raw_spin_lock_irq(&ctx->lock);
- task = ctx->task;
+again:
/*
- * Worse, we cannot even rely on the ctx actually existing anymore. If
- * between find_get_context() and perf_install_in_context() the task
- * went through perf_event_exit_task() its dead and we should not be
- * adding new events.
+ * Cannot use task_function_call() because we need to run on the task's
+ * CPU regardless of whether its current or not.
*/
- if (task == TASK_TOMBSTONE) {
+ if (!cpu_function_call(task_cpu(task), __perf_install_in_context, event))
+ return;
+
+ raw_spin_lock_irq(&ctx->lock);
+ task = ctx->task;
+ if (WARN_ON_ONCE(task == TASK_TOMBSTONE)) {
+ /*
+ * Cannot happen because we already checked above (which also
+ * cannot happen), and we hold ctx->mutex, which serializes us
+ * against perf_event_exit_task_context().
+ */
raw_spin_unlock_irq(&ctx->lock);
return;
}
- update_context_time(ctx);
+ raw_spin_unlock_irq(&ctx->lock);
/*
- * Update cgrp time only if current cgrp matches event->cgrp.
- * Must be done before calling add_event_to_ctx().
+ * Since !ctx->is_active doesn't mean anything, we must IPI
+ * unconditionally.
*/
- update_cgrp_time_from_event(event);
- add_event_to_ctx(event, ctx);
- raw_spin_unlock_irq(&ctx->lock);
-
- if (task)
- task_function_call(task, __perf_install_in_context, ctx);
- else
- cpu_function_call(cpu, __perf_install_in_context, ctx);
+ goto again;
}
/*
@@ -2219,17 +2265,18 @@ static void __perf_event_enable(struct perf_event *event,
event->state <= PERF_EVENT_STATE_ERROR)
return;
- update_context_time(ctx);
+ if (ctx->is_active)
+ ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+
__perf_event_mark_enabled(event);
if (!ctx->is_active)
return;
if (!event_filter_match(event)) {
- if (is_cgroup_event(event)) {
- perf_cgroup_set_timestamp(current, ctx); // XXX ?
+ if (is_cgroup_event(event))
perf_cgroup_defer_enabled(event);
- }
+ ctx_sched_in(ctx, cpuctx, EVENT_TIME, current);
return;
}
@@ -2237,8 +2284,10 @@ static void __perf_event_enable(struct perf_event *event,
* If the event is in a group and isn't the group leader,
* then don't put it on unless the group is on.
*/
- if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
+ if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE) {
+ ctx_sched_in(ctx, cpuctx, EVENT_TIME, current);
return;
+ }
task_ctx = cpuctx->task_ctx;
if (ctx->task)
@@ -2344,24 +2393,33 @@ static void ctx_sched_out(struct perf_event_context *ctx,
}
ctx->is_active &= ~event_type;
+ if (!(ctx->is_active & EVENT_ALL))
+ ctx->is_active = 0;
+
if (ctx->task) {
WARN_ON_ONCE(cpuctx->task_ctx != ctx);
if (!ctx->is_active)
cpuctx->task_ctx = NULL;
}
- update_context_time(ctx);
- update_cgrp_time_from_cpuctx(cpuctx);
- if (!ctx->nr_active)
+ is_active ^= ctx->is_active; /* changed bits */
+
+ if (is_active & EVENT_TIME) {
+ /* update (and stop) ctx time */
+ update_context_time(ctx);
+ update_cgrp_time_from_cpuctx(cpuctx);
+ }
+
+ if (!ctx->nr_active || !(is_active & EVENT_ALL))
return;
perf_pmu_disable(ctx->pmu);
- if ((is_active & EVENT_PINNED) && (event_type & EVENT_PINNED)) {
+ if (is_active & EVENT_PINNED) {
list_for_each_entry(event, &ctx->pinned_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
}
- if ((is_active & EVENT_FLEXIBLE) && (event_type & EVENT_FLEXIBLE)) {
+ if (is_active & EVENT_FLEXIBLE) {
list_for_each_entry(event, &ctx->flexible_groups, group_entry)
group_sched_out(event, cpuctx, ctx);
}
@@ -2641,18 +2699,6 @@ void __perf_event_task_sched_out(struct task_struct *task,
perf_cgroup_sched_out(task, next);
}
-static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
- struct perf_event_context *ctx)
-{
- if (!cpuctx->task_ctx)
- return;
-
- if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
- return;
-
- ctx_sched_out(ctx, cpuctx, EVENT_ALL);
-}
-
/*
* Called with IRQs disabled
*/
@@ -2735,7 +2781,7 @@ ctx_sched_in(struct perf_event_context *ctx,
if (likely(!ctx->nr_events))
return;
- ctx->is_active |= event_type;
+ ctx->is_active |= (event_type | EVENT_TIME);
if (ctx->task) {
if (!is_active)
cpuctx->task_ctx = ctx;
@@ -2743,18 +2789,24 @@ ctx_sched_in(struct perf_event_context *ctx,
WARN_ON_ONCE(cpuctx->task_ctx != ctx);
}
- now = perf_clock();
- ctx->timestamp = now;
- perf_cgroup_set_timestamp(task, ctx);
+ is_active ^= ctx->is_active; /* changed bits */
+
+ if (is_active & EVENT_TIME) {
+ /* start ctx time */
+ now = perf_clock();
+ ctx->timestamp = now;
+ perf_cgroup_set_timestamp(task, ctx);
+ }
+
/*
* First go through the list and put on any pinned groups
* in order to give them the best chance of going on.
*/
- if (!(is_active & EVENT_PINNED) && (event_type & EVENT_PINNED))
+ if (is_active & EVENT_PINNED)
ctx_pinned_sched_in(ctx, cpuctx);
/* Then walk through the lower prio flexible groups */
- if (!(is_active & EVENT_FLEXIBLE) && (event_type & EVENT_FLEXIBLE))
+ if (is_active & EVENT_FLEXIBLE)
ctx_flexible_sched_in(ctx, cpuctx);
}
@@ -3120,6 +3172,7 @@ static void perf_event_enable_on_exec(int ctxn)
cpuctx = __get_cpu_context(ctx);
perf_ctx_lock(cpuctx, ctx);
+ ctx_sched_out(ctx, cpuctx, EVENT_TIME);
list_for_each_entry(event, &ctx->event_list, event_entry)
enabled |= event_enable_on_exec(event, ctx);
@@ -3537,12 +3590,22 @@ static void unaccount_event(struct perf_event *event)
if (has_branch_stack(event))
dec = true;
- if (dec)
- static_key_slow_dec_deferred(&perf_sched_events);
+ if (dec) {
+ if (!atomic_add_unless(&perf_sched_count, -1, 1))
+ schedule_delayed_work(&perf_sched_work, HZ);
+ }
unaccount_event_cpu(event, event->cpu);
}
+static void perf_sched_delayed(struct work_struct *work)
+{
+ mutex_lock(&perf_sched_mutex);
+ if (atomic_dec_and_test(&perf_sched_count))
+ static_branch_disable(&perf_sched_events);
+ mutex_unlock(&perf_sched_mutex);
+}
+
/*
* The following implement mutual exclusion of events on "exclusive" pmus
* (PERF_PMU_CAP_EXCLUSIVE). Such pmus can only have one event scheduled
@@ -3752,30 +3815,42 @@ static void put_event(struct perf_event *event)
*/
int perf_event_release_kernel(struct perf_event *event)
{
- struct perf_event_context *ctx;
+ struct perf_event_context *ctx = event->ctx;
struct perf_event *child, *tmp;
+ /*
+ * If we got here through err_file: fput(event_file); we will not have
+ * attached to a context yet.
+ */
+ if (!ctx) {
+ WARN_ON_ONCE(event->attach_state &
+ (PERF_ATTACH_CONTEXT|PERF_ATTACH_GROUP));
+ goto no_ctx;
+ }
+
if (!is_kernel_event(event))
perf_remove_from_owner(event);
ctx = perf_event_ctx_lock(event);
WARN_ON_ONCE(ctx->parent_ctx);
- perf_remove_from_context(event, DETACH_GROUP | DETACH_STATE);
- perf_event_ctx_unlock(event, ctx);
+ perf_remove_from_context(event, DETACH_GROUP);
+ raw_spin_lock_irq(&ctx->lock);
/*
- * At this point we must have event->state == PERF_EVENT_STATE_EXIT,
- * either from the above perf_remove_from_context() or through
- * perf_event_exit_event().
+ * Mark this even as STATE_DEAD, there is no external reference to it
+ * anymore.
*
- * Therefore, anybody acquiring event->child_mutex after the below
- * loop _must_ also see this, most importantly inherit_event() which
- * will avoid placing more children on the list.
+ * Anybody acquiring event->child_mutex after the below loop _must_
+ * also see this, most importantly inherit_event() which will avoid
+ * placing more children on the list.
*
* Thus this guarantees that we will in fact observe and kill _ALL_
* child events.
*/
- WARN_ON_ONCE(event->state != PERF_EVENT_STATE_EXIT);
+ event->state = PERF_EVENT_STATE_DEAD;
+ raw_spin_unlock_irq(&ctx->lock);
+
+ perf_event_ctx_unlock(event, ctx);
again:
mutex_lock(&event->child_mutex);
@@ -3830,8 +3905,8 @@ again:
}
mutex_unlock(&event->child_mutex);
- /* Must be the last reference */
- put_event(event);
+no_ctx:
+ put_event(event); /* Must be the 'last' reference */
return 0;
}
EXPORT_SYMBOL_GPL(perf_event_release_kernel);
@@ -3988,7 +4063,7 @@ static bool is_event_hup(struct perf_event *event)
{
bool no_children;
- if (event->state != PERF_EVENT_STATE_EXIT)
+ if (event->state > PERF_EVENT_STATE_EXIT)
return false;
mutex_lock(&event->child_mutex);
@@ -7769,8 +7844,28 @@ static void account_event(struct perf_event *event)
if (is_cgroup_event(event))
inc = true;
- if (inc)
- static_key_slow_inc(&perf_sched_events.key);
+ if (inc) {
+ if (atomic_inc_not_zero(&perf_sched_count))
+ goto enabled;
+
+ mutex_lock(&perf_sched_mutex);
+ if (!atomic_read(&perf_sched_count)) {
+ static_branch_enable(&perf_sched_events);
+ /*
+ * Guarantee that all CPUs observe they key change and
+ * call the perf scheduling hooks before proceeding to
+ * install events that need them.
+ */
+ synchronize_sched();
+ }
+ /*
+ * Now that we have waited for the sync_sched(), allow further
+ * increments to by-pass the mutex.
+ */
+ atomic_inc(&perf_sched_count);
+ mutex_unlock(&perf_sched_mutex);
+ }
+enabled:
account_event_cpu(event, event->cpu);
}
@@ -8389,10 +8484,19 @@ SYSCALL_DEFINE5(perf_event_open,
if (move_group) {
gctx = group_leader->ctx;
mutex_lock_double(&gctx->mutex, &ctx->mutex);
+ if (gctx->task == TASK_TOMBSTONE) {
+ err = -ESRCH;
+ goto err_locked;
+ }
} else {
mutex_lock(&ctx->mutex);
}
+ if (ctx->task == TASK_TOMBSTONE) {
+ err = -ESRCH;
+ goto err_locked;
+ }
+
if (!perf_event_validate_size(event)) {
err = -E2BIG;
goto err_locked;
@@ -8509,7 +8613,12 @@ err_context:
perf_unpin_context(ctx);
put_ctx(ctx);
err_alloc:
- free_event(event);
+ /*
+ * If event_file is set, the fput() above will have called ->release()
+ * and that will take care of freeing the event.
+ */
+ if (!event_file)
+ free_event(event);
err_cpus:
put_online_cpus();
err_task:
@@ -8563,12 +8672,14 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
+ if (ctx->task == TASK_TOMBSTONE) {
+ err = -ESRCH;
+ goto err_unlock;
+ }
+
if (!exclusive_event_installable(event, ctx)) {
- mutex_unlock(&ctx->mutex);
- perf_unpin_context(ctx);
- put_ctx(ctx);
err = -EBUSY;
- goto err_free;
+ goto err_unlock;
}
perf_install_in_context(ctx, event, cpu);
@@ -8577,6 +8688,10 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
return event;
+err_unlock:
+ mutex_unlock(&ctx->mutex);
+ perf_unpin_context(ctx);
+ put_ctx(ctx);
err_free:
free_event(event);
err:
@@ -8695,7 +8810,7 @@ perf_event_exit_event(struct perf_event *child_event,
if (parent_event)
perf_group_detach(child_event);
list_del_event(child_event, child_ctx);
- child_event->state = PERF_EVENT_STATE_EXIT; /* see perf_event_release_kernel() */
+ child_event->state = PERF_EVENT_STATE_EXIT; /* is_event_hup() */
raw_spin_unlock_irq(&child_ctx->lock);
/*
@@ -9313,9 +9428,6 @@ void __init perf_event_init(void)
ret = init_hw_breakpoint();
WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
- /* do not patch jump label more than once per second */
- jump_label_rate_limit(&perf_sched_events, HZ);
-
/*
* Build time assertion that we keep the data_head at the intended
* location. IOW, validation we got the __reserved[] size right.