[tip:perf/core] perf: Disallow mmap() on per-task inherited events
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From: tip-bot for Peter Zijlstra on 18 May 2010 13:20 Commit-ID: c7920614cebbf269a7c8397ff959a8dcf727465c Gitweb: http://git.kernel.org/tip/c7920614cebbf269a7c8397ff959a8dcf727465c Author: Peter Zijlstra <a.p.zijlstra(a)chello.nl> AuthorDate: Tue, 18 May 2010 10:33:24 +0200 Committer: Ingo Molnar <mingo(a)elte.hu> 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(a)chello.nl> Cc: Mike Galbraith <efault(a)gmx.de> Cc: Paul Mackerras <paulus(a)samba.org> Cc: Arnaldo Carvalho de Melo <acme(a)redhat.com> Cc: Frederic Weisbecker <fweisbec(a)gmail.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo(a)elte.hu> --- 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-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |