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@xxxxxxxx> --- drivers/usb/class/cdc-acm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 3fda1ec961d7..f5886c512fec 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1634,12 +1634,13 @@ static int acm_resume(struct usb_interface *intf) 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); -- 2.26.2