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: git-fixes

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(-)

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index f61f2123a755..7a75aff78388 100644
--- a/drivers/hid/hidraw.c
+++ b/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)
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
index 935c3d0a3b63..8fe3efcb8327 100644
--- a/drivers/hid/uhid.c
+++ b/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 = {
-- 
2.16.4