From 050735b08ca8a016bbace4445fa025b88fee770b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 11 May 2010 11:51:53 +0200 Subject: [PATCH] perf: Fix exit() vs PERF_FORMAT_GROUP Both Stephane and Corey reported that PERF_FORMAT_GROUP didn't work as expected if the task the counters were attached to quit before the read() call. The cause is that we unconditionally destroy the grouping when we remove counters from their context. Fix this by splitting off the group destroy from the list removal such that perf_event_remove_from_context() does not do this and change perf_event_release() to do so. Reported-by: Corey Ashford Reported-by: Stephane Eranian Signed-off-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Paul Mackerras Cc: # .34.x LKML-Reference: <1273571513.5605.3527.camel@twins> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index a9047463fd83..c97e82518403 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -308,8 +308,6 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx) static void list_del_event(struct perf_event *event, struct perf_event_context *ctx) { - struct perf_event *sibling, *tmp; - if (list_empty(&event->group_entry)) return; ctx->nr_events--; @@ -333,6 +331,12 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx) */ if (event->state > PERF_EVENT_STATE_OFF) event->state = PERF_EVENT_STATE_OFF; +} + +static void +perf_destroy_group(struct perf_event *event, struct perf_event_context *ctx) +{ + struct perf_event *sibling, *tmp; /* * If this was a group event with sibling events then @@ -1868,6 +1872,12 @@ int perf_event_release_kernel(struct perf_event *event) { struct perf_event_context *ctx = event->ctx; + /* + * Remove from the PMU, can't get re-enabled since we got + * here because the last ref went. + */ + perf_event_disable(event); + WARN_ON_ONCE(ctx->parent_ctx); /* * There are two ways this annotation is useful: @@ -1882,7 +1892,10 @@ int perf_event_release_kernel(struct perf_event *event) * to trigger the AB-BA case. */ mutex_lock_nested(&ctx->mutex, SINGLE_DEPTH_NESTING); - perf_event_remove_from_context(event); + raw_spin_lock_irq(&ctx->lock); + list_del_event(event, ctx); + perf_destroy_group(event, ctx); + raw_spin_unlock_irq(&ctx->lock); mutex_unlock(&ctx->mutex); mutex_lock(&event->owner->perf_event_mutex); -- 2.30.2