Commit-ID: bb0ad4e22511e7caa715362945ad0766c7cca37e Gitweb: http://git.kernel.org/tip/bb0ad4e22511e7caa715362945ad0766c7cca37e Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> AuthorDate: Wed, 25 Mar 2009 12:48:31 +0100 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Wed, 25 Mar 2009 13:02:54 +0100 perf_counter: allow and require one-page mmap on counting counters A brainfart stopped single page mmap()s working. The rest of the code should be perfectly fine with not having any data pages. Reported-by: Paul Mackerras <paulus@xxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> LKML-Reference: <1237981712.7972.812.camel@twins> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/perf_counter.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index f3e1b27..95e0257 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1369,7 +1369,11 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) vma_size = vma->vm_end - vma->vm_start; nr_pages = (vma_size / PAGE_SIZE) - 1; - if (nr_pages == 0 || !is_power_of_2(nr_pages)) + /* + * If we have data pages ensure they're a power-of-two number, so we + * can do bitmasks instead of modulo. + */ + if (nr_pages != 0 && !is_power_of_2(nr_pages)) return -EINVAL; if (vma_size != PAGE_SIZE * (1 + nr_pages)) -- 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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