On Wed, Feb 13, 2013 at 12:45:52PM -0500, Benjamin LaHaise wrote:
> When the number of available events in the ring buffer is calculated,
> the avail calculation is incorrect when head == tail. This is harmless
> in aio_read_events_ring(), but in free_ioctx() leads to the subsequent
> WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr). Correct this.
>
> Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
> ---
> fs/aio.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 24ba228..dc52b0c 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -337,7 +337,8 @@ static void free_ioctx(struct kioctx *ctx)
> while (atomic_read(&ctx->reqs_available) < ctx->nr) {
> wait_event(ctx->wait, head != ctx->shadow_tail);
>
> - avail = (head < ctx->shadow_tail ? ctx->shadow_tail : ctx->nr) - head;
> + avail = (head <= ctx->shadow_tail ?
> + ctx->shadow_tail : ctx->nr) - head;
>
> atomic_add(avail, &ctx->reqs_available);
> head += avail;
> @@ -884,7 +885,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
> goto out;
>
> while (ret < nr) {
> - long avail = (head < ctx->shadow_tail
> + long avail = (head <= ctx->shadow_tail
> ? ctx->shadow_tail : ctx->nr) - head;
> struct io_event *ev;
> struct page *page;
> --
> 1.7.4.1
>
>
> --
> "Thought is the essence of where you are now."
Whoops!
Reviewed-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
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