Input: uinput - always report EPOLLOUT

dtor · dtor · commit add218099472 · 2019-12-13T15:00:30.000-08:00
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: d4b675e ("Input: uinput - fix returning EPOLLOUT from uinput_poll") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20191209202254.GA107567@dtor-ws Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git 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)

Original file line number	Diff line number	Diff line change
`@@ -689,13 +689,14 @@ static ssize_t uinput_read(struct file file, char __user buffer,`
`689`	`689`	`static __poll_t uinput_poll(struct file file, poll_table wait)`
`690`	`690`	`{`
`691`	`691`	`struct uinput_device *udev = file->private_data;`
	`692`	`+ __poll_t mask = EPOLLOUT \| EPOLLWRNORM; /* uinput is always writable */`
`692`	`693`
`693`	`694`	`poll_wait(file, &udev->waitq, wait);`
`694`	`695`
`695`	`696`	`if (udev->head != udev->tail)`
`696`		`- return EPOLLIN \| EPOLLRDNORM;`
	`697`	`+ mask \|= EPOLLIN \| EPOLLRDNORM;`
`697`	`698`
`698`		`- return EPOLLOUT \| EPOLLWRNORM;`
	`699`	`+ return mask;`
`699`	`700`	`}`
`700`	`701`
`701`	`702`	`static int uinput_release(struct inode inode, struct file file)`