On Tue, Mar 12, 2013 at 05:24:50PM +0100, Peter Zijlstra wrote:
> Right you are..
>
> How about something like the below; using that 0 << -1 is still 0.
hum.. we are obviously not on the same page wrt 'confusing' ;-)
looks ok, I'll test it
jirka
>
> ---
> kernel/events/ring_buffer.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
> index 23cb34f..e72ca70 100644
> --- a/kernel/events/ring_buffer.c
> +++ b/kernel/events/ring_buffer.c
> @@ -316,7 +316,7 @@ void rb_free(struct ring_buffer *rb)
> struct page *
> perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
> {
> - if (pgoff > (1UL << page_order(rb)))
> + if (pgoff > (rb->nr_pages << page_order(rb)))
> return NULL;
>
> return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
> @@ -336,10 +336,10 @@ static void rb_free_work(struct work_struct *work)
> int i, nr;
>
> rb = container_of(work, struct ring_buffer, work);
> - nr = 1 << page_order(rb);
> + nr = rb->nr_pages << page_order(rb);
>
> base = rb->user_page;
> - for (i = 0; i < nr + 1; i++)
> + for (i = 0; i <= nr; i++)
> perf_mmap_unmark_page(base + (i * PAGE_SIZE));
>
> vfree(base);
> @@ -373,7 +373,7 @@ struct ring_buffer *rb_alloc(int nr_pages, long
> watermark, int cpu, int flags)
> rb->user_page = all_buf;
> rb->data_pages[0] = all_buf + PAGE_SIZE;
> rb->page_order = ilog2(nr_pages);
> - rb->nr_pages = 1;
> + rb->nr_pages = !!nr_pages;
>
> ring_buffer_init(rb, watermark, flags);
>
>
>
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