[PATCH 4.4 01/76] hidraw: Return EPOLLOUT from hidraw_poll

Greg Kroah-Hartman
2020-01-22T09:30:30Z

From: Fabian Henneke <fabian.henneke@gmail.com>

[ 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@gmail.com>
In-reply-to: <CA+hv5qkyis03CgYTWeWX9cr0my-d2Oe+aZo+mjmWRXgjrGqyrw@mail.gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 627a24d3ea7c..27d2f5a48a11 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -265,7 +265,7 @@ 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