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io_uring/rw: forbid multishot async reads

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At the moment we can't sanely handle queuing an async request from a
multishot context, so disable them. It shouldn't matter as pollable
files / socekts don't normally do async.

Patching it in __io_read() is not the cleanest way, but it's simpler
than other options, so let's fix it there and clean up on top.

Cc: stable@vger.kernel.org
Reported-by: chase xd <sl1589472800@gmail.com>
Fixes: fc68fcda04 ("io_uring/rw: add support for IORING_OP_READ_MULTISHOT")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7d51732c125159d17db4fe16f51ec41b936973f8.1739919038.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2025-02-19 01:33:37 +00:00 • committed by Jens Axboe
parent fb3331f53e
commit 67b0025d19
1 changed files with 11 additions and 2 deletions
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13
io_uring/rw.c
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@ -880,7 +880,15 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
if (unlikely(ret))
return ret;
ret = io_iter_do_read(rw, &io->iter);
if (unlikely(req->opcode == IORING_OP_READ_MULTISHOT)) {
void *cb_copy = rw->kiocb.ki_complete;
rw->kiocb.ki_complete = NULL;
ret = io_iter_do_read(rw, &io->iter);
rw->kiocb.ki_complete = cb_copy;
} else {
ret = io_iter_do_read(rw, &io->iter);
}
/*
* Some file systems like to return -EOPNOTSUPP for an IOCB_NOWAIT
@ -904,7 +912,8 @@ static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
} else if (ret == -EIOCBQUEUED) {
return IOU_ISSUE_SKIP_COMPLETE;
} else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
(req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
(req->flags & REQ_F_NOWAIT) || !need_complete_io(req) ||
(issue_flags & IO_URING_F_MULTISHOT)) {
/* read all, failed, already did sync or don't want to retry */
goto done;
}