Re: [PATCH 5/6] io_uring/futex: ensure partial wakes are appropriately dequeued

[Gabriel Krisman Bertazi <krisman@suse.de>]

Jens Axboe <axboe@kernel.dk> writes:

> If a FUTEX_WAITV vectored operation is only partially woken, we
> should call __futex_wake_mark() on the queue to account for that.
> If not, then a later wakeup will wake the same entry, rather than
> the next one in line.
>
> Fixes: 8f350194d5cfd ("io_uring: add support for vectored futex waits")
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>

> ---
>  io_uring/futex.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/io_uring/futex.c b/io_uring/futex.c
> index fd503c24b428..9cc1788ef4c6 100644
> --- a/io_uring/futex.c
> +++ b/io_uring/futex.c
> @@ -159,8 +159,10 @@ static void io_futex_wakev_fn(struct wake_q_head *wake_q, struct futex_q *q)
>  	struct io_kiocb *req = q->wake_data;
>  	struct io_futexv_data *ifd = req->async_data;
>  
> -	if (!io_futexv_claim(ifd))
> +	if (!io_futexv_claim(ifd)) {
> +		__futex_wake_mark(q);
>  		return;
> +	}
>  	if (unlikely(!__futex_wake_mark(q)))
>  		return;

-- 
Gabriel Krisman Bertazi