usb: cdc-acm: fix devices not unthrottled on open

commit 6c4707f3f8c44ec18282e1c014c80e1c257042f9 upstream.

Currently CDC-ACM devices stay throttled when their TTY is closed while
throttled, stalling further communication attempts after the next open.

Unthrottling during open/activate got lost starting with kernel
3.0.0 and this patch reintroduces it.

Signed-off-by: Otto Meta <otto.patches@sister-shadow.de>
Acked-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e61d9c43e9855675f5814c785b7c9369b63a25c0..1094469f5f0bef7931732e39f40d5f6f77570bd1 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -498,6 +498,14 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp)
 
        usb_autopm_put_interface(acm->control);
 
+       /*
+        * Unthrottle device in case the TTY was closed while throttled.
+        */
+       spin_lock_irq(&acm->read_lock);
+       acm->throttled = 0;
+       acm->throttle_req = 0;
+       spin_unlock_irq(&acm->read_lock);
+
        if (acm_submit_read_urbs(acm, GFP_KERNEL))
                goto bail_out;