6.11-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
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 --- io_uring/rw.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)
--- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -973,17 +973,21 @@ int io_read_mshot(struct io_kiocb *req, 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_req_post_cqe(req, ret, cflags | IORING_CQE_F_MORE)) { @@ -1004,6 +1008,7 @@ int io_read_mshot(struct io_kiocb *req, * 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)