linux-kernel - [PATCH 5.15 002/132] io_uring: arm poll for non-nowait files

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Date:   Mon, 23 May 2022 19:03:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pavel Begunkov <asml.silence@...il.com>,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.15 002/132] io_uring: arm poll for non-nowait files

From: Pavel Begunkov <asml.silence@...il.com>

commit e74ead135bc4459f7d40b1f8edab1333a28b54e8 upstream.

Don't check if we can do nowait before arming apoll, there are several
reasons for that. First, we don't care much about files that don't
support nowait. Second, it may be useful -- we don't want to be taking
away extra workers from io-wq when it can go in some async. Even if it
will go through io-wq eventually, it make difference in the numbers of
workers actually used. And the last one, it's needed to clean nowait in
future commits.

[kernel test robot: fix unused-var]

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
Link: https://lore.kernel.org/r/9d06f3cb2c8b686d970269a87986f154edb83043.1634425438.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/io_uring.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5662,7 +5662,6 @@ static int io_arm_poll_handler(struct io
 	struct async_poll *apoll;
 	struct io_poll_table ipt;
 	__poll_t ret, mask = EPOLLONESHOT | POLLERR | POLLPRI;
-	int rw;
 
 	if (!req->file || !file_can_poll(req->file))
 		return IO_APOLL_ABORTED;
@@ -5672,7 +5671,6 @@ static int io_arm_poll_handler(struct io
 		return IO_APOLL_ABORTED;
 
 	if (def->pollin) {
-		rw = READ;
 		mask |= POLLIN | POLLRDNORM;
 
 		/* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */
@@ -5680,14 +5678,9 @@ static int io_arm_poll_handler(struct io
 		    (req->sr_msg.msg_flags & MSG_ERRQUEUE))
 			mask &= ~POLLIN;
 	} else {
-		rw = WRITE;
 		mask |= POLLOUT | POLLWRNORM;
 	}
 
-	/* if we can't nonblock try, then no point in arming a poll handler */
-	if (!io_file_supports_nowait(req, rw))
-		return IO_APOLL_ABORTED;
-
 	apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);
 	if (unlikely(!apoll))
 		return IO_APOLL_ABORTED;