io_uring: add IOU_STOP_MULTISHOT return code

For multishot we want a way to signal the caller that multishot has ended
but also this might not be an error return.

For example sockets return 0 when closed, which should end a multishot
recv, but still have a CQE with result 0

Introduce IOU_STOP_MULTISHOT which does this and indicates that the return
code is stored inside req->cqe

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-7-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index f77e4a5..e8da707 100644 (file)
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -15,6 +15,13 @@
 enum {
        IOU_OK                  = 0,
        IOU_ISSUE_SKIP_COMPLETE = -EIOCBQUEUED,
+
+       /*
+        * Intended only when both REQ_F_POLLED and REQ_F_APOLL_MULTISHOT
+        * are set to indicate to the poll runner that multishot should be
+        * removed and the result is set on req->cqe.res.
+        */
+       IOU_STOP_MULTISHOT      = -ECANCELED,
 };
 
 struct io_uring_cqe *__io_get_cqe(struct io_ring_ctx *ctx);

diff --git a/io_uring/poll.c b/io_uring/poll.c
index 922a3d1..64d426d 100644 (file)
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -195,6 +195,7 @@ static void io_poll_remove_entries(struct io_kiocb *req)
 enum {
        IOU_POLL_DONE = 0,
        IOU_POLL_NO_ACTION = 1,
+       IOU_POLL_REMOVE_POLL_USE_RES = 2,
 };
 
 /*
@@ -204,6 +205,8 @@ enum {
  * Returns a negative error on failure. IOU_POLL_NO_ACTION when no action require,
  * which is either spurious wakeup or multishot CQE is served.
  * IOU_POLL_DONE when it's done with the request, then the mask is stored in req->cqe.res.
+ * IOU_POLL_REMOVE_POLL_USE_RES indicates to remove multishot poll and that the result
+ * is stored in req->cqe.
  */
 static int io_poll_check_events(struct io_kiocb *req, bool *locked)
 {
@@ -244,6 +247,8 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
                                return -ECANCELED;
                } else {
                        ret = io_poll_issue(req, locked);
+                       if (ret == IOU_STOP_MULTISHOT)
+                               return IOU_POLL_REMOVE_POLL_USE_RES;
                        if (ret < 0)
                                return ret;
                }
@@ -268,7 +273,7 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
        if (ret == IOU_POLL_DONE) {
                struct io_poll *poll = io_kiocb_to_cmd(req);
                req->cqe.res = mangle_poll(req->cqe.res & poll->events);
-       } else {
+       } else if (ret != IOU_POLL_REMOVE_POLL_USE_RES) {
                req->cqe.res = ret;
                req_set_fail(req);
        }
@@ -291,7 +296,9 @@ static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
        io_poll_remove_entries(req);
        io_poll_tw_hash_eject(req, locked);
 
-       if (!ret)
+       if (ret == IOU_POLL_REMOVE_POLL_USE_RES)
+               io_req_complete_post(req);
+       else if (ret == IOU_POLL_DONE)
                io_req_task_submit(req, locked);
        else
                io_req_complete_failed(req, ret);