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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Marcel Holtmann <marcel@holtmann.org>,
        Jiri Kosina <jkosina@suse.cz>
Subject: [PATCH 4.14 09/39] HID: uhid: Fix returning EPOLLOUT from uhid_char_poll
Date:   Tue, 14 Jan 2020 11:01:43 +0100
Message-Id: <20200114094341.250899773@linuxfoundation.org>
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From: Marcel Holtmann <marcel@holtmann.org>

commit be54e7461ffdc5809b67d2aeefc1ddc9a91470c7 upstream.

Always return EPOLLOUT from uhid_char_poll to allow polling /dev/uhid
for writable state.

Fixes: 1f9dec1e0164 ("HID: uhid: allow poll()'ing on uhid devices")
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>

---
 drivers/hid/uhid.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/hid/uhid.c
+++ b/drivers/hid/uhid.c
@@ -25,6 +25,7 @@
 #include <linux/spinlock.h>
 #include <linux/uhid.h>
 #include <linux/wait.h>
+#include <linux/eventpoll.h>
 
 #define UHID_NAME	"uhid"
 #define UHID_BUFSIZE	32
@@ -774,7 +775,7 @@ static unsigned int uhid_char_poll(struc
 	if (uhid->head != uhid->tail)
 		return POLLIN | POLLRDNORM;
 
-	return 0;
+	return EPOLLOUT | EPOLLWRNORM;
 }
 
 static const struct file_operations uhid_fops = {