From: Jens Axboe axboe@kernel.dk
commit 10c873334febaeea9aa0c25c10b5ac0951b77a5f upstream.
We currently check REQ_F_POLLED before arming async poll for a notification to retry. If it's set, then we don't allow poll and will punt to io-wq instead. This is done to prevent a situation where a buggy driver will repeatedly return that there's space/data available yet we get -EAGAIN.
However, if we already transferred data, then it should be safe to rely on poll again. Gate the check on whether or not REQ_F_PARTIAL_IO is also set.
Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- io_uring/io_uring.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 75d833269751..cc8e13de5fa9 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -5694,7 +5694,7 @@ static int io_arm_poll_handler(struct io_kiocb *req)
if (!req->file || !file_can_poll(req->file)) return IO_APOLL_ABORTED; - if (req->flags & REQ_F_POLLED) + if ((req->flags & (REQ_F_POLLED|REQ_F_PARTIAL_IO)) == REQ_F_POLLED) return IO_APOLL_ABORTED; if (!def->pollin && !def->pollout) return IO_APOLL_ABORTED; @@ -5710,7 +5710,10 @@ static int io_arm_poll_handler(struct io_kiocb *req) mask |= POLLOUT | POLLWRNORM; }
- apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC); + if (req->flags & REQ_F_POLLED) + apoll = req->apoll; + else + apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC); if (unlikely(!apoll)) return IO_APOLL_ABORTED; apoll->double_poll = NULL;