diff options
author | Ingo Molnar <mingo@kernel.org> | 2013-11-04 07:49:35 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2013-11-04 07:49:35 +0100 |
commit | 2a3ede8cb2ddee5885518e4232aca13056f9a6e0 (patch) | |
tree | 79b2b4e060a97b1e7c60d58549f8c97cb15db5dd /include/uapi/linux/perf_event.h | |
parent | 0e73453e172aaa38fd59fd4d3fc589e8fc9b9a70 (diff) | |
parent | 215432ed30393ed4a8f77db0a1fe34523c48cdba (diff) |
Merge branch 'perf/urgent' into perf/core to fix conflicts
Conflicts:
tools/perf/bench/numa.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/uapi/linux/perf_event.h')
-rw-r--r-- | include/uapi/linux/perf_event.h | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index da48837d617..e1802d6153a 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -479,13 +479,15 @@ struct perf_event_mmap_page { /* * Control data for the mmap() data buffer. * - * User-space reading the @data_head value should issue an rmb(), on - * SMP capable platforms, after reading this value -- see - * perf_event_wakeup(). + * User-space reading the @data_head value should issue an smp_rmb(), + * after reading this value. * * When the mapping is PROT_WRITE the @data_tail value should be - * written by userspace to reflect the last read data. In this case - * the kernel will not over-write unread data. + * written by userspace to reflect the last read data, after issueing + * an smp_mb() to separate the data read from the ->data_tail store. + * In this case the kernel will not over-write unread data. + * + * See perf_output_put_handle() for the data ordering. */ __u64 data_head; /* head in the data section */ __u64 data_tail; /* user-space written tail */ |