From: Oliver Neukum <oneukum@suse.com> 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> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- 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 a1fa16a03ab9d..7f4f21ba8efcf 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1682,12 +1682,13 @@ 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); -- 2.25.1