io_uring: refactor io_arm_poll_handler()

gcc 11 goes a weird path and duplicates most of io_arm_poll_handler()
for READ and WRITE cases. Help it and move all pollin vs pollout
specific bits under a single if-else, so there is no temptation for this
kind of unfolding.

before vs after:
   text    data     bss     dec     hex filename
  85362   12650       8   98020   17ee4 ./fs/io_uring.o
  85186   12650       8   97844   17e34 ./fs/io_uring.o

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1deea0037293a922a0358e2958384b2e42437885.1624739600.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ab30c0a..bfba755 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5172,19 +5172,29 @@ static int io_arm_poll_handler(struct io_kiocb *req)
        struct io_ring_ctx *ctx = req->ctx;
        struct async_poll *apoll;
        struct io_poll_table ipt;
-       __poll_t mask, ret;
+       __poll_t ret, mask = EPOLLONESHOT | POLLERR | POLLPRI;
        int rw;
 
        if (!req->file || !file_can_poll(req->file))
                return IO_APOLL_ABORTED;
        if (req->flags & REQ_F_POLLED)
                return IO_APOLL_ABORTED;
-       if (def->pollin)
+       if (!def->pollin && !def->pollout)
+               return IO_APOLL_ABORTED;
+
+       if (def->pollin) {
                rw = READ;
-       else if (def->pollout)
+               mask |= POLLIN | POLLRDNORM;
+
+               /* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */
+               if ((req->opcode == IORING_OP_RECVMSG) &&
+                   (req->sr_msg.msg_flags & MSG_ERRQUEUE))
+                       mask &= ~POLLIN;
+       } else {
                rw = WRITE;
-       else
-               return IO_APOLL_ABORTED;
+               mask |= POLLOUT | POLLWRNORM;
+       }
+
        /* if we can't nonblock try, then no point in arming a poll handler */
        if (!io_file_supports_async(req, rw))
                return IO_APOLL_ABORTED;
@@ -5193,23 +5203,8 @@ static int io_arm_poll_handler(struct io_kiocb *req)
        if (unlikely(!apoll))
                return IO_APOLL_ABORTED;
        apoll->double_poll = NULL;
-
-       req->flags |= REQ_F_POLLED;
        req->apoll = apoll;
-
-       mask = EPOLLONESHOT;
-       if (def->pollin)
-               mask |= POLLIN | POLLRDNORM;
-       if (def->pollout)
-               mask |= POLLOUT | POLLWRNORM;
-
-       /* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */
-       if ((req->opcode == IORING_OP_RECVMSG) &&
-           (req->sr_msg.msg_flags & MSG_ERRQUEUE))
-               mask &= ~POLLIN;
-
-       mask |= POLLERR | POLLPRI;
-
+       req->flags |= REQ_F_POLLED;
        ipt.pt._qproc = io_async_queue_proc;
 
        ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask,