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

Browse Source 
BugLink: https://bugs.launchpad.net/bugs/2097301

Commit c9d952b9103b600ddafc5d1c0e2f2dbd30f0b805 upstream.

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: 2a975d426c82 ("io_uring/rw: don't allow multishot reads without NOWAIT support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
This commit is contained in:
Jens Axboe
2024-10-05 19:06:50 -06:00
committed by Mehmet Basaran
parent f1ae90ff0c
commit eaa4945886
1 changed files with 12 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
io_uring/rw.c
+12 -7
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@@ -964,17 +964,21 @@ 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;
}
/*
* Any successful return value will keep the multishot read armed.
*/
if (ret > 0 && req->flags & REQ_F_APOLL_MULTISHOT) {
} else if (ret <= 0) {
io_kbuf_recycle(req, issue_flags);
if (ret < 0)
req_set_fail(req);
} else {
/*
* 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, issue_flags);
if (!(req->flags & REQ_F_APOLL_MULTISHOT))
goto done;
rw->len = 0; /* similarly to above, reset len to 0 */
if (io_fill_cqe_req_aux(req,
@@ -997,6 +1001,7 @@ 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);
if (issue_flags & IO_URING_F_MULTISHOT)
return IOU_STOP_MULTISHOT;