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 <>
Cc: stable <>
Signed-off-by: Greg Kroah-Hartman <>
1 file changed