δΊ 2015/1/27 17:55, Kaixu Xia ει: ping... > The function is_power_of_2() also do the check on nr_pages, > so the first check performed is unnecessary. On the other > hand, the key point is to ensure @nr_pages is a power-of-two > number and mostly @nr_pages is a nonzero value, so in the > most cases, the function is_power_of_2() will be called. > > Signed-off-by: Kaixu Xia <xiaka...@huawei.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 882f835..abb57c2 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -4268,7 +4268,7 @@ 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 (nr_pages != 0 && !is_power_of_2(nr_pages)) > + if (!is_power_of_2(nr_pages)) > return -EINVAL; > > if (vma_size != PAGE_SIZE * (1 + nr_pages)) >
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