HID: hidraw, uhid: Always report EPOLLOUT

hidraw and uhid device nodes are always available for writing so we should
always report EPOLLOUT and EPOLLWRNORM bits, not only in the cases when
there is nothing to read.

Reported-by: Linus Torvalds <[email protected]>
Fixes: be54e74 ("HID: uhid: Fix returning EPOLLOUT from uhid_char_poll")
Fixes: 9f3b61d ("HID: hidraw: Fix returning EPOLLOUT from hidraw_poll")
Signed-off-by: Jiri Kosina <[email protected]>

Author: Jiri Kosina

drivers/hid/hidraw.c

@@ -249,13 +249,14 @@ static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t
 static __poll_t hidraw_poll(struct file *file, poll_table *wait)
 {
 	struct hidraw_list *list = file->private_data;
+	__poll_t mask = EPOLLOUT | EPOLLWRNORM; /* hidraw is always writable */
 
 	poll_wait(file, &list->hidraw->wait, wait);
 	if (list->head != list->tail)
-		return EPOLLIN | EPOLLRDNORM;
+		mask |= EPOLLIN | EPOLLRDNORM;
 	if (!list->hidraw->exist)
-		return EPOLLERR | EPOLLHUP;
-	return EPOLLOUT | EPOLLWRNORM;
+		mask |= EPOLLERR | EPOLLHUP;
+	return mask;
 }
 
 static int hidraw_open(struct inode *inode, struct file *file)

drivers/hid/uhid.c

@@ -766,13 +766,14 @@ static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
 static __poll_t uhid_char_poll(struct file *file, poll_table *wait)
 {
 	struct uhid_device *uhid = file->private_data;
+	__poll_t mask = EPOLLOUT | EPOLLWRNORM; /* uhid is always writable */
 
 	poll_wait(file, &uhid->waitq, wait);
 
 	if (uhid->head != uhid->tail)
-		return EPOLLIN | EPOLLRDNORM;
+		mask |= EPOLLIN | EPOLLRDNORM;
 
-	return EPOLLOUT | EPOLLWRNORM;
+	return mask;
 }
 
 static const struct file_operations uhid_fops = {