[PATCH 4.9 01/97] hidraw: Return EPOLLOUT from hidraw_poll

[Greg Kroah-Hartman]

From: Fabian Henneke <fabian.henneke@xxxxxxxxx>

[ Upstream commit 378b80370aa1fe50f9c48a3ac8af3e416e73b89f ]

Always return EPOLLOUT from hidraw_poll when a device is connected.
This is safe since writes are always possible (but will always block).

hidraw does not support non-blocking writes and instead always calls
blocking backend functions on write requests. Hence, so far, a call to
poll never returned EPOLLOUT, which confuses tools like socat.

Signed-off-by: Fabian Henneke <fabian.henneke@xxxxxxxxx>
In-reply-to: <CA+hv5qkyis03CgYTWeWX9cr0my-d2Oe+aZo+mjmWRXgjrGqyrw@xxxxxxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/hid/hidraw.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 750c16897130..225456c1a39a 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -260,7 +260,7 @@ static unsigned int hidraw_poll(struct file *file, poll_table *wait)
 
 	poll_wait(file, &list->hidraw->wait, wait);
 	if (list->head != list->tail)
-		return POLLIN | POLLRDNORM;
+		return POLLIN | POLLRDNORM | POLLOUT;
 	if (!list->hidraw->exist)
 		return POLLERR | POLLHUP;
 	return 0;
-- 
2.20.1