From: Oliver Neukum <oliver@neukum.org>
Date: Wed, 9 Sep 2009 15:08:50 +0000 (+0200)
Subject: USB: O_NONBLOCK in read path of skeleton
X-Git-Tag: firefly_0821_release~12454^2~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8cd01664344e983d73a85ce604f7c23f475cf303;p=firefly-linux-kernel-4.4.55.git

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>
---

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);