[3.11.y.z extended stable] Patch "USB: usb_wwan: fix potential blocked I/O after resume" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    USB: usb_wwan: fix potential blocked I/O after resume

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 73e3d9ac020daddae68846e4e740ec626762a47a Mon Sep 17 00:00:00 2001
From: Johan Hovold <jhovold at gmail.com>
Date: Mon, 26 May 2014 19:23:18 +0200
Subject: USB: usb_wwan: fix potential blocked I/O after resume

commit fb7ad4f93d9f0f7d49beda32f5e7becb94b29a4d upstream.

Keep trying to submit urbs rather than bail out on first read-urb
submission error, which would also prevent I/O for any further ports
from being resumed.

Instead keep an error count, for all types of failed submissions, and
let USB core know that something went wrong.

Also make sure to always clear the suspended flag. Currently a failed
read-urb submission would prevent cached writes as well as any
subsequent writes from being submitted until next suspend-resume cycle,
something which may not even necessarily happen.

Note that USB core currently only logs an error if an interface resume
failed.

Fixes: 383cedc3bb43 ("USB: serial: full autosuspend support for the
option driver")

Signed-off-by: Johan Hovold <jhovold at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ luis: backported to 3.11: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/serial/usb_wwan.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index be684101257c..f5a001929029 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -613,12 +613,12 @@ static void unbusy_queued_urb(struct urb *urb, struct usb_wwan_port_private *por
 	}
 }

-static void play_delayed(struct usb_serial_port *port)
+static int play_delayed(struct usb_serial_port *port)
 {
 	struct usb_wwan_intf_private *data;
 	struct usb_wwan_port_private *portdata;
 	struct urb *urb;
-	int err;
+	int err = 0;

 	portdata = usb_get_serial_port_data(port);
 	data = port->serial->private;
@@ -635,6 +635,8 @@ static void play_delayed(struct usb_serial_port *port)
 			break;
 		}
 	}
+
+	return err;
 }

 int usb_wwan_resume(struct usb_serial *serial)
@@ -644,7 +646,8 @@ int usb_wwan_resume(struct usb_serial *serial)
 	struct usb_wwan_intf_private *intfdata = serial->private;
 	struct usb_wwan_port_private *portdata;
 	struct urb *urb;
-	int err = 0;
+	int err;
+	int err_count = 0;

 	spin_lock_irq(&intfdata->susp_lock);
 	for (i = 0; i < serial->num_ports; i++) {
@@ -663,25 +666,31 @@ int usb_wwan_resume(struct usb_serial *serial)
 				dev_err(&port->dev,
 					"%s: submit int urb failed: %d\n",
 					__func__, err);
+				err_count++;
 			}
 		}

+		err = play_delayed(port);
+		if (err)
+			err_count++;
+
 		for (j = 0; j < N_IN_URB; j++) {
 			urb = portdata->in_urbs[j];
 			err = usb_submit_urb(urb, GFP_ATOMIC);
 			if (err < 0) {
 				dev_err(&port->dev, "%s: Error %d for bulk URB %d\n",
 					__func__, err, i);
-				spin_unlock_irq(&intfdata->susp_lock);
-				goto err_out;
+				err_count++;
 			}
 		}
-		play_delayed(port);
 	}
 	intfdata->suspended = 0;
 	spin_unlock_irq(&intfdata->susp_lock);
-err_out:
-	return err;
+
+	if (err_count)
+		return -EIO;
+
+	return 0;
 }
 EXPORT_SYMBOL(usb_wwan_resume);
 #endif
--
1.9.1