when nonblock read the condition check (file->f_flags & O_NONBLOCK)
always be true,
signal_pending and device exist checking never get a chance to run, so
the user mode code always
get EAGAIN even if device removed. move nonblock mode checking to the
last can fix this problem.
Signed-off-by: Founder Fang <founder.fang@xxxxxxxxx>
--- hid-git/drivers/hid/hidraw.c.orig 2012-11-21 14:37:04.977106383 +0800
+++ hid-git/drivers/hid/hidraw.c 2012-11-21 14:40:35.882152200 +0800
@@ -57,10 +57,6 @@ static ssize_t hidraw_read(struct file *
set_current_state(TASK_INTERRUPTIBLE);
while (list->head == list->tail) {
- if (file->f_flags & O_NONBLOCK) {
- ret = -EAGAIN;
- break;
- }
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
@@ -69,6 +65,10 @@ static ssize_t hidraw_read(struct file *
ret = -EIO;
break;
}
+ if (file->f_flags & O_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
/* allow O_NONBLOCK to work well from other threads */
mutex_unlock(&list->read_mutex);
--
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