From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 26 Jan 2016 11:15:37 +0000 (+0100)
Subject: perf: Update locking order
X-Git-Tag: v4.9.8~2761^2~8
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=07c4a776135ea6d808ea19aabeb51de6b8648402;p=platform%2Fkernel%2Flinux-rpi3.git

perf: Update locking order

Update the locking order to note that ctx::lock nests inside of
child_mutex, as per:

  perf_ioctl():                ctx::mutex
  -> perf_event_for_each():    event::child_mutex
    -> _perf_event_enable():   ctx::lock

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 024adf0..d345964 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1086,8 +1086,8 @@ static void put_ctx(struct perf_event_context *ctx)
  * Lock order:
  *	task_struct::perf_event_mutex
  *	  perf_event_context::mutex
- *	    perf_event_context::lock
  *	    perf_event::child_mutex;
+ *	      perf_event_context::lock
  *	    perf_event::mmap_mutex
  *	    mmap_sem
  */