diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-05-20 14:35:15 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-05-21 11:37:57 +0200 |
| commit | 0f139300c9057c16b5833a4636b715b104fe0baa (patch) | |
| tree | e7b19c4fc8599fb683cee1b618b28a8aa16208e2 /kernel/perf_event.c | |
| parent | 1c024eca51fdc965290acf342ae16a476c2189d0 (diff) | |
perf: Ensure that IOC_OUTPUT isn't used to create multi-writer buffers
Since we want to ensure buffers only have a single
writer, we must avoid creating one with multiple.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100521090710.528215873@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_event.c')
| -rw-r--r-- | kernel/perf_event.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 3f2cc313ee2..7a932526946 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -4920,6 +4920,13 @@ static int perf_event_set_output(struct perf_event *event, int output_fd) int fput_needed = 0; int ret = -EINVAL; + /* + * Don't allow output of inherited per-task events. This would + * create performance issues due to cross cpu access. + */ + if (event->cpu == -1 && event->attr.inherit) + return -EINVAL; + if (!output_fd) goto set; @@ -4940,6 +4947,18 @@ static int perf_event_set_output(struct perf_event *event, int output_fd) if (event->data) goto out; + /* + * Don't allow cross-cpu buffers + */ + if (output_event->cpu != event->cpu) + goto out; + + /* + * If its not a per-cpu buffer, it must be the same task. + */ + if (output_event->cpu == -1 && output_event->ctx != event->ctx) + goto out; + atomic_long_inc(&output_file->f_count); set: |