USB: CDC-ACM: fix poison/unpoison imbalance
commit a8b3b519618f30a87a304c4e120267ce6f8dc68a upstream.
suspend() does its poisoning conditionally, resume() does it
unconditionally. On a device with combined interfaces this
will balance, on a device with two interfaces the counter will
go negative and resubmission will fail.
Both actions need to be done conditionally.
Fixes: 6069e3e927c8f ("USB: cdc-acm: untangle a circular dependency between callback and softint")
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210421074513.4327-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e793593..bc035ba 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1637,12 +1637,13 @@
struct urb *urb;
int rv = 0;
- acm_unpoison_urbs(acm);
spin_lock_irq(&acm->write_lock);
if (--acm->susp_count)
goto out;
+ acm_unpoison_urbs(acm);
+
if (tty_port_initialized(&acm->port)) {
rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC);
