From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Wed, 30 Dec 2015 04:59:08 +0000 (+0800)
Subject: usb: cdc-acm: handle unlinked urb in acm read callback
X-Git-Tag: v4.1.18~93
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6cdc037a9b649209051e3c982d5fcaf31274cb55;p=platform%2Fkernel%2Flinux-exynos.git

usb: cdc-acm: handle unlinked urb in acm read callback

[ Upstream commit 19454462acb1bdef80542061bdc9b410e4ed1ff6 ]

In current acm driver, the bulk-in callback function ignores the
URBs unlinked in usb core.

This causes unexpected data loss in some cases. For example,
runtime suspend entry will unlinked all urbs and set urb->status
to -ENOENT even those urbs might have data not processed yet.
Hence, data loss occurs.

This patch lets bulk-in callback function handle unlinked urbs
to avoid data loss.

Signed-off-by: Tang Jian Qiang <jianqiang.tang@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: stable@vger.kernel.org
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 0fe15ae..2bf51b2 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -432,7 +432,8 @@ static void acm_read_bulk_callback(struct urb *urb)
 		set_bit(rb->index, &acm->read_urbs_free);
 		dev_dbg(&acm->data->dev, "%s - non-zero urb status: %d\n",
 							__func__, status);
-		return;
+		if ((status != -ENOENT) || (urb->actual_length == 0))
+			return;
 	}
 
 	usb_mark_last_busy(acm->dev);