io_uring: clean up io_poll_check_events return values

The values returned are a bit confusing, where 0 and 1 have implied
meaning, so add some definitions for them.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-6-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/poll.c b/io_uring/poll.c
index fa25b88..922a3d1 100644 (file)
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -192,13 +192,18 @@ static void io_poll_remove_entries(struct io_kiocb *req)
        rcu_read_unlock();
 }
 
+enum {
+       IOU_POLL_DONE = 0,
+       IOU_POLL_NO_ACTION = 1,
+};
+
 /*
  * All poll tw should go through this. Checks for poll events, manages
  * references, does rewait, etc.
  *
- * Returns a negative error on failure. >0 when no action require, which is
- * either spurious wakeup or multishot CQE is served. 0 when it's done with
- * the request, then the mask is stored in req->cqe.res.
+ * 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.
  */
 static int io_poll_check_events(struct io_kiocb *req, bool *locked)
 {
@@ -214,10 +219,11 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
 
                /* tw handler should be the owner, and so have some references */
                if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK)))
-                       return 0;
+                       return IOU_POLL_DONE;
                if (v & IO_POLL_CANCEL_FLAG)
                        return -ECANCELED;
 
+               /* the mask was stashed in __io_poll_execute */
                if (!req->cqe.res) {
                        struct poll_table_struct pt = { ._key = req->apoll_events };
                        req->cqe.res = vfs_poll(req->file, &pt) & req->apoll_events;
@@ -226,7 +232,7 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
                if ((unlikely(!req->cqe.res)))
                        continue;
                if (req->apoll_events & EPOLLONESHOT)
-                       return 0;
+                       return IOU_POLL_DONE;
 
                /* multishot, just fill a CQE and proceed */
                if (!(req->flags & REQ_F_APOLL_MULTISHOT)) {
@@ -238,7 +244,7 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
                                return -ECANCELED;
                } else {
                        ret = io_poll_issue(req, locked);
-                       if (ret)
+                       if (ret < 0)
                                return ret;
                }
 
@@ -248,7 +254,7 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
                 */
        } while (atomic_sub_return(v & IO_POLL_REF_MASK, &req->poll_refs));
 
-       return 1;
+       return IOU_POLL_NO_ACTION;
 }
 
 static void io_poll_task_func(struct io_kiocb *req, bool *locked)
@@ -256,12 +262,11 @@ static void io_poll_task_func(struct io_kiocb *req, bool *locked)
        int ret;
 
        ret = io_poll_check_events(req, locked);
-       if (ret > 0)
+       if (ret == IOU_POLL_NO_ACTION)
                return;
 
-       if (!ret) {
+       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 {
                req->cqe.res = ret;
@@ -280,7 +285,7 @@ static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
        int ret;
 
        ret = io_poll_check_events(req, locked);
-       if (ret > 0)
+       if (ret == IOU_POLL_NO_ACTION)
                return;
 
        io_poll_remove_entries(req);