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[3.5.y.z,extended,stable] Patch "USB: cdc-wdm: fix race between interrupt handler and tasklet" has been added to staging queue

Message ID 1379705554-14040-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Sept. 20, 2013, 7:32 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    USB: cdc-wdm: fix race between interrupt handler and tasklet

to the linux-3.5.y-queue branch of the 3.5.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-3.5.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 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

From f3b2ed0e54d3a1a608fa2c10ad6d3b68cda296ad Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.de>
Date: Tue, 6 Aug 2013 14:22:59 +0200
Subject: [PATCH] USB: cdc-wdm: fix race between interrupt handler and tasklet

commit 6dd433e6cf2475ce8abec1b467720858c24450eb upstream.

Both could want to submit the same URB. Some checks of the flag
intended to prevent that were missing.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/usb/class/cdc-wdm.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--
1.8.3.2
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Patch

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 97c1d8e..7c25710 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -233,6 +233,7 @@  skip_error:
 static void wdm_int_callback(struct urb *urb)
 {
 	int rv = 0;
+	int responding;
 	int status = urb->status;
 	struct wdm_device *desc;
 	struct usb_cdc_notification *dr;
@@ -286,8 +287,8 @@  static void wdm_int_callback(struct urb *urb)

 	spin_lock(&desc->iuspin);
 	clear_bit(WDM_READ, &desc->flags);
-	set_bit(WDM_RESPONDING, &desc->flags);
-	if (!test_bit(WDM_DISCONNECTING, &desc->flags)
+	responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
+	if (!responding && !test_bit(WDM_DISCONNECTING, &desc->flags)
 		&& !test_bit(WDM_SUSPENDING, &desc->flags)) {
 		rv = usb_submit_urb(desc->response, GFP_ATOMIC);
 		dev_dbg(&desc->intf->dev, "%s: usb_submit_urb %d",
@@ -691,16 +692,20 @@  static void wdm_rxwork(struct work_struct *work)
 {
 	struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
 	unsigned long flags;
-	int rv;
+	int rv = 0;
+	int responding;

 	spin_lock_irqsave(&desc->iuspin, flags);
 	if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 		spin_unlock_irqrestore(&desc->iuspin, flags);
 	} else {
+		responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 		spin_unlock_irqrestore(&desc->iuspin, flags);
-		rv = usb_submit_urb(desc->response, GFP_KERNEL);
+		if (!responding)
+			rv = usb_submit_urb(desc->response, GFP_KERNEL);
 		if (rv < 0 && rv != -EPERM) {
 			spin_lock_irqsave(&desc->iuspin, flags);
+			clear_bit(WDM_RESPONDING, &desc->flags);
 			if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 				schedule_work(&desc->rxwork);
 			spin_unlock_irqrestore(&desc->iuspin, flags);