USB: O_NONBLOCK in read path of skeleton

Non blocking IO is supported in the read path of usb-skeleton.
This is done by just not blocking. As support for handling signals
without stopping IO is already there, it can be used for O_NONBLOCK, too.

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 768fda9064e9..ef8c877cdd41 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -268,6 +268,11 @@ retry:
         spin_unlock_irq(&dev->err_lock);
 
         if (ongoing_io) {
+                /* nonblocking IO shall not wait */
+                if (file->f_flags & O_NONBLOCK) {
+                        rv = -EAGAIN;
+                        goto exit;
+                }
                 /*
                  * IO may take forever
                  * hence wait in an interruptible state
@@ -351,8 +356,9 @@ retry:
                 rv = skel_do_read_io(dev, count);
                 if (rv < 0)
                         goto exit;
-                else
+                else if (!file->f_flags & O_NONBLOCK)
                         goto retry;
+                rv = -EAGAIN;
         }
 exit:
         mutex_unlock(&dev->io_mutex);