diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 142 |
1 files changed, 79 insertions, 63 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 8e1b8126c0e4..45fa7167cee2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2209,6 +2209,26 @@ out: perf_event__header_size(leader); } +static void sync_child_event(struct perf_event *child_event); + +static void perf_child_detach(struct perf_event *event) +{ + struct perf_event *parent_event = event->parent; + + if (!(event->attach_state & PERF_ATTACH_CHILD)) + return; + + event->attach_state &= ~PERF_ATTACH_CHILD; + + if (WARN_ON_ONCE(!parent_event)) + return; + + lockdep_assert_held(&parent_event->child_mutex); + + sync_child_event(event); + list_del_init(&event->child_list); +} + static bool is_orphaned_event(struct perf_event *event) { return event->state == PERF_EVENT_STATE_DEAD; @@ -2316,6 +2336,7 @@ group_sched_out(struct perf_event *group_event, } #define DETACH_GROUP 0x01UL +#define DETACH_CHILD 0x02UL /* * Cross CPU call to remove a performance event @@ -2339,6 +2360,8 @@ __perf_remove_from_context(struct perf_event *event, event_sched_out(event, cpuctx, ctx); if (flags & DETACH_GROUP) perf_group_detach(event); + if (flags & DETACH_CHILD) + perf_child_detach(event); list_del_event(event, ctx); if (!ctx->nr_events && ctx->is_active) { @@ -2367,25 +2390,21 @@ static void perf_remove_from_context(struct perf_event *event, unsigned long fla lockdep_assert_held(&ctx->mutex); - event_function_call(event, __perf_remove_from_context, (void *)flags); - /* - * The above event_function_call() can NO-OP when it hits - * TASK_TOMBSTONE. In that case we must already have been detached - * from the context (by perf_event_exit_event()) but the grouping - * might still be in-tact. + * Because of perf_event_exit_task(), perf_remove_from_context() ought + * to work in the face of TASK_TOMBSTONE, unlike every other + * event_function_call() user. */ - WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT); - if ((flags & DETACH_GROUP) && - (event->attach_state & PERF_ATTACH_GROUP)) { - /* - * Since in that case we cannot possibly be scheduled, simply - * detach now. - */ - raw_spin_lock_irq(&ctx->lock); - perf_group_detach(event); + raw_spin_lock_irq(&ctx->lock); + if (!ctx->is_active) { + __perf_remove_from_context(event, __get_cpu_context(ctx), + ctx, (void *)flags); raw_spin_unlock_irq(&ctx->lock); + return; } + raw_spin_unlock_irq(&ctx->lock); + + event_function_call(event, __perf_remove_from_context, (void *)flags); } /* @@ -12249,14 +12268,17 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu) } EXPORT_SYMBOL_GPL(perf_pmu_migrate_context); -static void sync_child_event(struct perf_event *child_event, - struct task_struct *child) +static void sync_child_event(struct perf_event *child_event) { struct perf_event *parent_event = child_event->parent; u64 child_val; - if (child_event->attr.inherit_stat) - perf_event_read_event(child_event, child); + if (child_event->attr.inherit_stat) { + struct task_struct *task = child_event->ctx->task; + + if (task && task != TASK_TOMBSTONE) + perf_event_read_event(child_event, task); + } child_val = perf_event_count(child_event); @@ -12271,60 +12293,53 @@ static void sync_child_event(struct perf_event *child_event, } static void -perf_event_exit_event(struct perf_event *child_event, - struct perf_event_context *child_ctx, - struct task_struct *child) +perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx) { - struct perf_event *parent_event = child_event->parent; + struct perf_event *parent_event = event->parent; + unsigned long detach_flags = 0; - /* - * Do not destroy the 'original' grouping; because of the context - * switch optimization the original events could've ended up in a - * random child task. - * - * If we were to destroy the original group, all group related - * operations would cease to function properly after this random - * child dies. - * - * Do destroy all inherited groups, we don't care about those - * and being thorough is better. - */ - raw_spin_lock_irq(&child_ctx->lock); - WARN_ON_ONCE(child_ctx->is_active); + if (parent_event) { + /* + * Do not destroy the 'original' grouping; because of the + * context switch optimization the original events could've + * ended up in a random child task. + * + * If we were to destroy the original group, all group related + * operations would cease to function properly after this + * random child dies. + * + * Do destroy all inherited groups, we don't care about those + * and being thorough is better. + */ + detach_flags = DETACH_GROUP | DETACH_CHILD; + mutex_lock(&parent_event->child_mutex); + } - if (parent_event) - perf_group_detach(child_event); - list_del_event(child_event, child_ctx); - perf_event_set_state(child_event, PERF_EVENT_STATE_EXIT); /* is_event_hup() */ - raw_spin_unlock_irq(&child_ctx->lock); + perf_remove_from_context(event, detach_flags); + + raw_spin_lock_irq(&ctx->lock); + if (event->state > PERF_EVENT_STATE_EXIT) + perf_event_set_state(event, PERF_EVENT_STATE_EXIT); + raw_spin_unlock_irq(&ctx->lock); /* - * Parent events are governed by their filedesc, retain them. + * Child events can be freed. */ - if (!parent_event) { - perf_event_wakeup(child_event); + if (parent_event) { + mutex_unlock(&parent_event->child_mutex); + /* + * Kick perf_poll() for is_event_hup(); + */ + perf_event_wakeup(parent_event); + free_event(event); + put_event(parent_event); return; } - /* - * Child events can be cleaned up. - */ - - sync_child_event(child_event, child); /* - * Remove this event from the parent's list - */ - WARN_ON_ONCE(parent_event->ctx->parent_ctx); - mutex_lock(&parent_event->child_mutex); - list_del_init(&child_event->child_list); - mutex_unlock(&parent_event->child_mutex); - - /* - * Kick perf_poll() for is_event_hup(). + * Parent events are governed by their filedesc, retain them. */ - perf_event_wakeup(parent_event); - free_event(child_event); - put_event(parent_event); + perf_event_wakeup(event); } static void perf_event_exit_task_context(struct task_struct *child, int ctxn) @@ -12381,7 +12396,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn) perf_event_task(child, child_ctx, 0); list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry) - perf_event_exit_event(child_event, child_ctx, child); + perf_event_exit_event(child_event, child_ctx); mutex_unlock(&child_ctx->mutex); @@ -12641,6 +12656,7 @@ inherit_event(struct perf_event *parent_event, */ raw_spin_lock_irqsave(&child_ctx->lock, flags); add_event_to_ctx(child_event, child_ctx); + child_event->attach_state |= PERF_ATTACH_CHILD; raw_spin_unlock_irqrestore(&child_ctx->lock, flags); /* |