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io_uring/rw: fix cflags posting for single issue multishot read

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If multishot gets disabled, and hence the request will get terminated
rather than persist for more iterations, then posting the CQE with the
right cflags is still important. Most notably, the buffer reference
needs to be included.

Refactor the return of __io_read() a bit, so that the provided buffer
is always put correctly, and hence returned to the application.

Reported-by: Sharon Rosner <Sharon Rosner>
Link: https://github.com/axboe/liburing/issues/1257
Cc: stable@vger.kernel.org
Fixes: 2a975d426c ("io_uring/rw: don't allow multishot reads without NOWAIT support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-10-05 19:06:50 -06:00
parent c314094cb4
commit c9d952b910
1 changed files with 12 additions and 7 deletions
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19
io_uring/rw.c
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@ -972,17 +972,21 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
if (issue_flags & IO_URING_F_MULTISHOT)
return IOU_ISSUE_SKIP_COMPLETE;
return -EAGAIN;
}
} else if (ret <= 0) {
io_kbuf_recycle(req, issue_flags);
if (ret < 0)
req_set_fail(req);
} else {
/*
* Any successful return value will keep the multishot read armed.
*/
if (ret > 0 && req->flags & REQ_F_APOLL_MULTISHOT) {
/*
* Put our buffer and post a CQE. If we fail to post a CQE, then
* Any successful return value will keep the multishot read
* armed, if it's still set. Put our buffer and post a CQE. If
* we fail to post a CQE, or multishot is no longer set, then
* jump to the termination path. This request is then done.
*/
cflags = io_put_kbuf(req, ret, issue_flags);
if (!(req->flags & REQ_F_APOLL_MULTISHOT))
goto done;
rw->len = 0; /* similarly to above, reset len to 0 */
if (io_req_post_cqe(req, ret, cflags | IORING_CQE_F_MORE)) {
@ -1003,6 +1007,7 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
* Either an error, or we've hit overflow posting the CQE. For any
* multishot request, hitting overflow will terminate it.
*/
done:
io_req_set_res(req, ret, cflags);
io_req_rw_cleanup(req, issue_flags);
if (issue_flags & IO_URING_F_MULTISHOT)