From 6050cb0b0b366092d1383bc23d7b16cd26db00f0 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Tue, 23 Jul 2013 02:30:59 +0200 Subject: [PATCH] perf: Fix branch stack refcount leak on callchain init failure On callchain buffers allocation failure, free_event() is called and all the accounting performed in perf_event_alloc() for that event is cancelled. But if the event has branch stack sampling, it is unaccounted as well from the branch stack sampling events refcounts. This is a bug because this accounting is performed after the callchain buffer allocation. As a result, the branch stack sampling events refcount can become negative. To fix this, move the branch stack event accounting before the callchain buffer allocation. Reported-by: Peter Zijlstra Signed-off-by: Frederic Weisbecker Cc: Jiri Olsa Cc: Namhyung Kim Cc: Arnaldo Carvalho de Melo Cc: Stephane Eranian Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1374539466-4799-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 127411400116..f35aa7e69e2d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6567,6 +6567,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, atomic_inc(&nr_comm_events); if (event->attr.task) atomic_inc(&nr_task_events); + if (has_branch_stack(event)) { + static_key_slow_inc(&perf_sched_events.key); + if (!(event->attach_state & PERF_ATTACH_TASK)) + atomic_inc(&per_cpu(perf_branch_stack_events, + event->cpu)); + } if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) { err = get_callchain_buffers(); if (err) { @@ -6574,12 +6580,6 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, return ERR_PTR(err); } } - if (has_branch_stack(event)) { - static_key_slow_inc(&perf_sched_events.key); - if (!(event->attach_state & PERF_ATTACH_TASK)) - atomic_inc(&per_cpu(perf_branch_stack_events, - event->cpu)); - } } return event; -- GitLab