diff options
author | Peter Zijlstra <peterz@infradead.org> | 2025-01-17 17:27:07 +0300 |
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committer | Peter Zijlstra <peterz@infradead.org> | 2025-04-08 21:55:46 +0300 |
commit | 59f3aa4a3ee27e96132e16d2d2bdc3acadb4bf79 (patch) | |
tree | d0bcf8a462a5eb4f2e045e29640a47c0e4cb762e | |
parent | 0a00a43b8c200df5b9ca2b3e1726479b5916264b (diff) | |
download | linux-59f3aa4a3ee27e96132e16d2d2bdc3acadb4bf79.tar.xz |
perf: Simplify perf_event_free_task() wait
Simplify the code by moving the duplicated wakeup condition into
put_ctx().
Notably, wait_var_event() is in perf_event_free_task() and will have
set ctx->task = TASK_TOMBSTONE.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lkml.kernel.org/r/20250307193723.044499344@infradead.org
-rw-r--r-- | kernel/events/core.c | 25 |
1 files changed, 3 insertions, 22 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 3c92b7520688..fa6dab08be47 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1270,6 +1270,9 @@ static void put_ctx(struct perf_event_context *ctx) if (ctx->task && ctx->task != TASK_TOMBSTONE) put_task_struct(ctx->task); call_rcu(&ctx->rcu_head, free_ctx); + } else if (ctx->task == TASK_TOMBSTONE) { + smp_mb(); /* pairs with wait_var_event() */ + wake_up_var(&ctx->refcount); } } @@ -5729,8 +5732,6 @@ int perf_event_release_kernel(struct perf_event *event) again: mutex_lock(&event->child_mutex); list_for_each_entry(child, &event->child_list, child_list) { - void *var = NULL; - /* * Cannot change, child events are not migrated, see the * comment with perf_event_ctx_lock_nested(). @@ -5765,40 +5766,20 @@ again: if (tmp == child) { perf_remove_from_context(child, DETACH_GROUP | DETACH_CHILD); list_add(&child->child_list, &free_list); - } else { - var = &ctx->refcount; } mutex_unlock(&event->child_mutex); mutex_unlock(&ctx->mutex); put_ctx(ctx); - if (var) { - /* - * If perf_event_free_task() has deleted all events from the - * ctx while the child_mutex got released above, make sure to - * notify about the preceding put_ctx(). - */ - smp_mb(); /* pairs with wait_var_event() */ - wake_up_var(var); - } goto again; } mutex_unlock(&event->child_mutex); list_for_each_entry_safe(child, tmp, &free_list, child_list) { - void *var = &child->ctx->refcount; - list_del(&child->child_list); /* Last reference unless ->pending_task work is pending */ put_event(child); - - /* - * Wake any perf_event_free_task() waiting for this event to be - * freed. - */ - smp_mb(); /* pairs with wait_var_event() */ - wake_up_var(var); } no_ctx: |