diff options
| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-03-25 12:48:31 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-04-06 09:30:35 +0200 |
| commit | 7730d8655880f41f2ea519aca2ca6a1413dfd2c9 (patch) | |
| tree | 2115b531fcc45d22f79828e21cc3f15dd95f01fd | |
| parent | 00f0ad73ac90e3fba8b4cbe4cf21b2fb9a56cb72 (diff) | |
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@samba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Orig-LKML-Reference: <1237981712.7972.812.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | 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 f3e1b27bc1b..95e02575546 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)) |