x86/perf: Clarify why x86_pmu_event_mapped() isn't racy
authorAndy Lutomirski <luto@kernel.org>
Thu, 16 Mar 2017 19:59:40 +0000 (12:59 -0700)
committerIngo Molnar <mingo@kernel.org>
Fri, 17 Mar 2017 07:28:26 +0000 (08:28 +0100)
commit4b07372a32c0c1505a7634ad7e607d83340ef645
tree3af5756c3cfe90f9f994356941b5435312168f70
parent5dc855d44c2ad960a86f593c60461f1ae1566b6d
x86/perf: Clarify why x86_pmu_event_mapped() isn't racy

Naively, it looks racy, but ->mmap_sem saves it.  Add a comment and a
lockdep assertion.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.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>
Link: http://lkml.kernel.org/r/03a1e629063899168dfc4707f3bb6e581e21f5c6.1489694270.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/events/core.c