HID: hidraw: Fix returning EPOLLOUT from hidraw_poll

commit 9f3b61dc1dd7b81e99e7ed23776bb64a35f39e1a upstream.

When polling a connected /dev/hidrawX device, it is useful to get the
EPOLLOUT when writing is possible. Since writing is possible as soon as
the device is connected, always return it.

Right now EPOLLOUT is only returned when there are also input reports
are available. This works if devices start sending reports when
connected, but some HID devices might need an output report first before
sending any input reports. This change will allow using EPOLLOUT here as
well.

Fixes: 378b80370aa1 ("hidraw: Return EPOLLOUT from hidraw_poll")
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index bbc6ec1aa5cb13eb4a856972a2d22739b78cc846..c25e95c19cad3753ad4cf22454dcde6cd3a5ac00 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -252,10 +252,10 @@ static __poll_t hidraw_poll(struct file *file, poll_table *wait)
 
        poll_wait(file, &list->hidraw->wait, wait);
        if (list->head != list->tail)
-               return EPOLLIN | EPOLLRDNORM | EPOLLOUT;
+               return EPOLLIN | EPOLLRDNORM;
        if (!list->hidraw->exist)
                return EPOLLERR | EPOLLHUP;
-       return 0;
+       return EPOLLOUT | EPOLLWRNORM;
 }
 
 static int hidraw_open(struct inode *inode, struct file *file)