[PATCH 3.16 169/245] hidraw: Return EPOLLOUT from hidraw_poll

Ben Hutchings
2020-04-23T23:13:19Z

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

commit 378b80370aa1fe50f9c48a3ac8af3e416e73b89f upstream.

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>
[bwh: Backported to 3.16: s/EPOLL/POLL/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/hid/hidraw.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -265,7 +265,7 @@ static unsigned int hidraw_poll(struct f

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;