Commit-ID: c7920614cebbf269a7c8397ff959a8dcf727465c Gitweb: http://git.kernel.org/tip/c7920614cebbf269a7c8397ff959a8dcf727465c Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> AuthorDate: Tue, 18 May 2010 10:33:24 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Tue, 18 May 2010 18:35:48 +0200 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@xxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- 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 6ae6218..ff5d430 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; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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