commit
e144ed28bed10684f9aaec6325ed974d53f76110 upstream.
Fix race between write() and resume() due to improper locking that could
lead to writes being reordered.
Resume must be done atomically and susp_count be protected by the
write_lock in order to prevent racing with write(). This could otherwise
lead to writes being reordered if write() grabs the write_lock after
susp_count is decremented, but before the delayed urb is submitted.
Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
struct acm *acm = usb_get_intfdata(intf);
struct acm_wb *wb;
int rv = 0;
struct acm *acm = usb_get_intfdata(intf);
struct acm_wb *wb;
int rv = 0;
spin_lock_irq(&acm->read_lock);
spin_lock_irq(&acm->read_lock);
- acm->susp_count -= 1;
- cnt = acm->susp_count;
- spin_unlock_irq(&acm->read_lock);
+ spin_lock(&acm->write_lock);
+ if (--acm->susp_count)
+ goto out;
if (test_bit(ASYNCB_INITIALIZED, &acm->port.flags)) {
if (test_bit(ASYNCB_INITIALIZED, &acm->port.flags)) {
- rv = usb_submit_urb(acm->ctrlurb, GFP_NOIO);
+ rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC);
- spin_lock_irq(&acm->write_lock);
if (acm->delayed_wb) {
wb = acm->delayed_wb;
acm->delayed_wb = NULL;
if (acm->delayed_wb) {
wb = acm->delayed_wb;
acm->delayed_wb = NULL;
- spin_unlock_irq(&acm->write_lock);
- } else {
- spin_unlock_irq(&acm->write_lock);
* do the write path at all cost
*/
if (rv < 0)
* do the write path at all cost
*/
if (rv < 0)
- rv = acm_submit_read_urbs(acm, GFP_NOIO);
+ rv = acm_submit_read_urbs(acm, GFP_ATOMIC);
+out:
+ spin_unlock(&acm->write_lock);
+ spin_unlock_irq(&acm->read_lock);