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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-05-18 10:33:24 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-05-18 18:35:48 +0200 |
| commit | c7920614cebbf269a7c8397ff959a8dcf727465c (patch) | |
| tree | d1ca38ee77cb4160660efb97b8bdc2e5c44967c1 /kernel | |
| parent | a19d35c11fd559dd7dfd5a2078df7c9af74a5d88 (diff) | |
| download | linux-c7920614cebbf269a7c8397ff959a8dcf727465c.tar.gz linux-c7920614cebbf269a7c8397ff959a8dcf727465c.tar.bz2 linux-c7920614cebbf269a7c8397ff959a8dcf727465c.zip | |
perf: Disallow mmap() on per-task inherited events
Since we now have working per-task-per-cpu events for
a while, disallow mmap() on per-task inherited
events. Those things were a performance problem
anyway, and doing away with it allows us to optimize
the buffer somewhat by assuming there is only a
single writer.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/perf_event.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 6ae62186dd0c..ff5d430d45a7 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -2593,6 +2593,14 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) long user_extra, extra; int ret = 0; + /* + * Don't allow mmap() of inherited per-task counters. This would + * create a performance issue due to all children writing to the + * same buffer. + */ + if (event->cpu == -1 && event->attr.inherit) + return -EINVAL; + if (!(vma->vm_flags & VM_SHARED)) return -EINVAL; |