linux-kernel - [PATCH] Input: uinput - always report EPOLLOUT

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Message-ID: <20191209202254.GA107567@dtor-ws>
Date:   Mon, 9 Dec 2019 12:22:54 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     linux-input@...r.kernel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] Input: uinput - always report EPOLLOUT

uinput device is always available for writing so we should always report
EPOLLOUT and EPOLLWRNORM bits, not only when there is nothing to read from
the device.

Fixes: d4b675e1b527 ("Input: uinput - fix returning EPOLLOUT from uinput_poll")
Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: stable@...r.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/input/misc/uinput.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index fd253781be71..0bb456015d8f 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -689,13 +689,14 @@ static ssize_t uinput_read(struct file *file, char __user *buffer,
 static __poll_t uinput_poll(struct file *file, poll_table *wait)
 {
 	struct uinput_device *udev = file->private_data;
+	__poll_t mask = EPOLLOUT | EPOLLWRNORM; /* uinput is always writable */
 
 	poll_wait(file, &udev->waitq, wait);
 
 	if (udev->head != udev->tail)
-		return EPOLLIN | EPOLLRDNORM;
+		mask |= EPOLLIN | EPOLLRDNORM;
 
-	return EPOLLOUT | EPOLLWRNORM;
+	return mask;
 }
 
 static int uinput_release(struct inode *inode, struct file *file)
-- 
2.24.0.393.g34dc348eaf-goog


-- 
Dmitry