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>
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index ae87116..42c61cc 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -233,6 +233,7 @@
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 @@
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",
@@ -687,16 +688,20 @@
{
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);