Patch "usb: cdc-acm: handle unlinked urb in acm read callback" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-cdc-acm-handle-unlinked-urb-in-acm-read-callback.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 19454462acb1bdef80542061bdc9b410e4ed1ff6 Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Wed, 30 Dec 2015 12:59:08 +0800
Subject: usb: cdc-acm: handle unlinked urb in acm read callback

From: Lu Baolu <baolu.lu@linux.intel.com>

commit 19454462acb1bdef80542061bdc9b410e4ed1ff6 upstream.

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>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/class/cdc-acm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -428,7 +428,8 @@ static void acm_read_bulk_callback(struc
 		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);


Patches currently in stable-queue which might be from baolu.lu@linux.intel.com are

queue-4.4/usb-xhci-handle-both-ssic-ports-in-pme-stuck-quirk.patch
queue-4.4/usb-cdc-acm-send-zero-packet-for-intel-7260-modem.patch
queue-4.4/usb-xhci-apply-xhci_pme_stuck_quirk-to-intel-broxton-m-platforms.patch
queue-4.4/usb-cdc-acm-handle-unlinked-urb-in-acm-read-callback.patch