From 9e635c2851df6caee651e589fbf937b637973c91 Mon Sep 17 00:00:00 2001
From: Jiri Kosina <jkosina@suse.cz>
Date: Fri, 10 Jan 2020 15:32:51 +0100
Subject: [PATCH] HID: hidraw, uhid: Always report EPOLLOUT
Git-commit: 9e635c2851df6caee651e589fbf937b637973c91
Patch-mainline: v5.5-rc6
References: bsc#1051510

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 <torvalds@linux-foundation.org>
Fixes: be54e7461ffdc ("HID: uhid: Fix returning EPOLLOUT from uhid_char_poll")
Fixes: 9f3b61dc1dd7b ("HID: hidraw: Fix returning EPOLLOUT from hidraw_poll")
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/hid/hidraw.c |    7 ++++---
 drivers/hid/uhid.c   |    5 +++--
 2 files changed, 7 insertions(+), 5 deletions(-)

--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -257,13 +257,14 @@ out:
 static unsigned int hidraw_poll(struct file *file, poll_table *wait)
 {
 	struct hidraw_list *list = file->private_data;
+	unsigned int mask = POLLOUT | POLLWRNORM; /* hidraw is always writable */
 
 	poll_wait(file, &list->hidraw->wait, wait);
 	if (list->head != list->tail)
-		return POLLIN | POLLRDNORM;
+		mask |= POLLIN | POLLRDNORM;
 	if (!list->hidraw->exist)
-		return POLLERR | POLLHUP;
-	return POLLOUT | POLLWRNORM;
+		mask |= POLLERR | POLLHUP;
+	return mask;
 }
 
 static int hidraw_open(struct inode *inode, struct file *file)
--- a/drivers/hid/uhid.c
+++ b/drivers/hid/uhid.c
@@ -767,13 +767,14 @@ unlock:
 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
 {
 	struct uhid_device *uhid = file->private_data;
+	unsigned int mask = POLLOUT | POLLWRNORM; /* uhid is always writable */
 
 	poll_wait(file, &uhid->waitq, wait);
 
 	if (uhid->head != uhid->tail)
-		return POLLIN | POLLRDNORM;
+		mask |= POLLIN | POLLRDNORM;
 
-	return POLLOUT | POLLWRNORM;
+	return mask;
 }
 
 static const struct file_operations uhid_fops = {