Commit c27e0882 authored Sep 09, 2020 by Laurent Gauthier Committed by Jiri Kosina Sep 09, 2020

HID: hid-debug: 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.

Based on similar to patches hidraw and hiddev by Founder Fang
<founder.fang@gmail.com> and Jiri Kosina <jkosina@suse.cz>.

Signed-off-by: Laurent Gauthier <laurent.gauthier@soccasys.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

parent fc3abb53

drivers/hid/hid-debug.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -1101,11 +1101,6 @@ static ssize_t hid_debug_events_read(struct file file, char __user buffer,
		set_current_state(TASK_INTERRUPTIBLE);

		while (kfifo_is_empty(&list->hid_debug_fifo)) {
		if (file->f_flags & O_NONBLOCK) {
		ret = -EAGAIN;
		break;
		}

		if (signal_pending(current)) {
		ret = -ERESTARTSYS;
		break;
		@@ -1122,6 +1117,11 @@ static ssize_t hid_debug_events_read(struct file file, char __user buffer,
		goto out;
		}

		if (file->f_flags & O_NONBLOCK) {
		ret = -EAGAIN;
		break;
		}

		/* allow O_NONBLOCK from other threads */
		mutex_unlock(&list->read_mutex);
		schedule();

Admin message