HID: hidraw, uhid: Always report EPOLLOUT

BugLink: https://bugs.launchpad.net/bugs/1861934
[ Upstream commit 9e635c2851df6caee651e589fbf937b637973c91 ]

hidraw and uhid device nodes are always available for writing so we should
always report EPOLLOUT and EPOLLWRNORM bits, not only in the cases when
there is nothing to read.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: be54e7461ffdc ("HID: uhid: Fix returning EPOLLOUT from uhid_char_poll")
Fixes: 9f3b61dc1dd7b ("HID: hidraw: Fix returning EPOLLOUT from hidraw_poll")
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 1abf5008def0b1f8b3b1c5e6c3061f404cf6e8de..5243c412081917e2f452e48bd01d48539595ef4a 100644 (file)
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -257,13 +257,14 @@ out:
 static unsigned int hidraw_poll(struct file *file, poll_table *wait)
 {
        struct hidraw_list *list = file->private_data;
+       unsigned int mask = POLLOUT | POLLWRNORM; /* hidraw is always writable */
 
        poll_wait(file, &list->hidraw->wait, wait);
        if (list->head != list->tail)
-               return POLLIN | POLLRDNORM;
+               mask |= POLLIN | POLLRDNORM;
        if (!list->hidraw->exist)
-               return POLLERR | POLLHUP;
-       return POLLOUT | POLLWRNORM;
+               mask |= POLLERR | POLLHUP;
+       return mask;
 }
 
 static int hidraw_open(struct inode *inode, struct file *file)

diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
index e63b761f600a222e3ea7c827f9b1b65518162176..c749f449c7cb357e65b9c588c8039904badd35d3 100644 (file)
--- a/drivers/hid/uhid.c
+++ b/drivers/hid/uhid.c
@@ -769,13 +769,14 @@ unlock:
 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
 {
        struct uhid_device *uhid = file->private_data;
+       unsigned int mask = POLLOUT | POLLWRNORM; /* uhid is always writable */
 
        poll_wait(file, &uhid->waitq, wait);
 
        if (uhid->head != uhid->tail)
-               return POLLIN | POLLRDNORM;
+               mask |= POLLIN | POLLRDNORM;
 
-       return EPOLLOUT | EPOLLWRNORM;
+       return mask;
 }
 
 static const struct file_operations uhid_fops = {