From: Otto Meta <otto.patches@sister-shadow.de>
Date: Wed, 6 Jun 2012 16:46:21 +0000 (+0200)
Subject: usb: cdc-acm: fix devices not unthrottled on open
X-Git-Tag: v3.2.21~4
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d65602a876757353c0a5f9e7fd4c3f8c98477404;p=thirdparty%2Fkernel%2Fstable.git

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 e61d9c43e9855..1094469f5f0be 100644
--- 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;