HID: hiddev: fix nonblocking read semantics wrt EIO/ERESTARTSYS

When the file has been open in non-blocking mode, EIO or ERESTARTSYS
would never be returned even if they should (for example when device
has been unplugged, you want EIO and not EAGAIN to be returned).

Move the O_NONBLOCK check after other checks have been performed.

Base on similar patch done to hidraw by
Founder Fang <founder.fang@gmail.com>

Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index 711c9656ec0fa69d16dde39b0f806aa2d36202bf..87bd64959a91b4bed5e3745751e237f78ac4470a 100644 (file)
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -361,10 +361,6 @@ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t coun
                        prepare_to_wait(&list->hiddev->wait, &wait, TASK_INTERRUPTIBLE);
 
                        while (list->head == list->tail) {
-                               if (file->f_flags & O_NONBLOCK) {
-                                       retval = -EAGAIN;
-                                       break;
-                               }
                                if (signal_pending(current)) {
                                        retval = -ERESTARTSYS;
                                        break;
@@ -373,6 +369,10 @@ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t coun
                                        retval = -EIO;
                                        break;
                                }
+                               if (file->f_flags & O_NONBLOCK) {
+                                       retval = -EAGAIN;
+                                       break;
+                               }
 
                                /* let O_NONBLOCK tasks run */
                                mutex_unlock(&list->thread_lock);