Commit-ID: a4f4bb6d0c69d0bb573f1d9e6f1b806f9b038b19
Gitweb: http://git.kernel.org/tip/a4f4bb6d0c69d0bb573f1d9e6f1b806f9b038b19
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 24 Feb 2016 18:45:42 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 25 Feb 2016 08:42:33 +0100
perf: Allow perf_release() with !event->ctx
In the err_file: fput(event_file) case, the event will not yet have
been attached to a context. However perf_release() does assume it has
been. Cure this.
Tested-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: dvyukov@xxxxxxxxxx
Cc: eranian@xxxxxxxxxx
Cc: oleg@xxxxxxxxxx
Cc: panand@xxxxxxxxxx
Cc: sasha.levin@xxxxxxxxxx
Cc: vince@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20160224174947.793996260@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 211a5ce..d5299e2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3754,9 +3754,19 @@ 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);
@@ -3832,8 +3842,8 @@ 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);
--
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