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[4.2.y-ckt,24/64] usb: cdc-acm: handle unlinked urb in acm read callback

Message ID 1454625887-18915-25-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Feb. 4, 2016, 10:44 p.m. UTC 
4.2.8-ckt4 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/usb/class/cdc-acm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 26ca4f9..8cd193b 100644
--- 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);