Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 18/20] Revert "perf: Remove the extra validity check on nr_pages" | Date | Tue, 3 Mar 2015 00:26:07 -0300 |
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From: Kan Liang <kan.liang@intel.com>
This reverts commit 74390aa55678 ("perf: Remove the extra validity check on nr_pages")
nr_pages equals to number of pages - 1 in perf_mmap. So nr_pages = 0 is valid.
So the nr_pages != 0 && !is_power_of_2(nr_pages) are all needed for checking. Otherwise, for example, perf test 6 failed.
# perf test 6 6: x86 rdpmc test :Error: mmap() syscall returned with (Invalid argument) FAILED!
Signed-off-by: Kan Liang <kan.liang@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Kaixu Xia <xiakaixu@huawei.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1425280466-7830-1-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index af924bc38121..8bb20cc39a92 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4446,7 +4446,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) * If we have rb pages ensure they're a power-of-two number, so we * can do bitmasks instead of modulo. */ - if (!is_power_of_2(nr_pages)) + if (nr_pages != 0 && !is_power_of_2(nr_pages)) return -EINVAL; if (vma_size != PAGE_SIZE * (1 + nr_pages)) -- 1.9.3
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