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USB: CDC-ACM: fix poison/unpoison imbalance

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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>
This commit is contained in:
Oliver Neukum 2021-04-21 09:45:13 +02:00 committed by Greg Kroah-Hartman
parent ca91fd8c76
commit a8b3b51961
1 changed files with 2 additions and 1 deletions
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3
drivers/usb/class/cdc-acm.c
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@ -1624,12 +1624,13 @@ 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);