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

LuBaolu · gregkh · commit 19454462acb1 · 2016-01-24T21:06:21.000-08:00
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-&gt;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 &lt;jianqiang.tang@intel.com&gt;
Signed-off-by: Lu Baolu &lt;baolu.lu@linux.intel.com&gt;
Cc: stable@vger.kernel.org
Acked-by: Oliver Neukum &lt;oneukum@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
@@ -428,7 +428,8 @@ 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);

Original file line number	Diff line number	Diff line change
`@@ -428,7 +428,8 @@ static void acm_read_bulk_callback(struct urb *urb)`
`428`	`428`	`set_bit(rb->index, &acm->read_urbs_free);`
`429`	`429`	`dev_dbg(&acm->data->dev, "%s - non-zero urb status: %d\n",`
`430`	`430`	`__func__, status);`
`431`		`- return;`
	`431`	`+ if ((status != -ENOENT) \|\| (urb->actual_length == 0))`
	`432`	`+ return;`
`432`	`433`	`}`
`433`	`434`
`434`	`435`	`usb_mark_last_busy(acm->dev);`