4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
commit 2497128133f8169b24b928852ba6eae34fc495e5 upstream.
If port100_send_ack() was called twice or more, it has race to hangup.
port100_send_ack() port100_send_ack()
init_completion()
[...]
dev->cmd_cancel = true
/* this removes previous from completion */
init_completion()
[...]
dev->cmd_cancel = true
wait_for_completion()
/* never be waked up */
wait_for_completion()
Like above race, this code is not assuming port100_send_ack() is
called twice or more.
To fix, this checks dev->cmd_cancel to know if prior cancel is
in-flight or not. And never be remove prior task from completion by
using reinit_completion(), so this guarantees to be waked up properly
soon or later.
Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/nfc/port100.c | 37 ++++++++++++++++++++++++-------------
1 file changed, 24 insertions(+), 13 deletions(-)
--- a/drivers/nfc/port100.c
+++ b/drivers/nfc/port100.c
@@ -725,23 +725,33 @@ static int port100_submit_urb_for_ack(st
static int port100_send_ack(struct port100 *dev)
{
- int rc;
+ int rc = 0;
mutex_lock(&dev->out_urb_lock);
- init_completion(&dev->cmd_cancel_done);
-
- usb_kill_urb(dev->out_urb);
+ /*
+ * If prior cancel is in-flight (dev->cmd_cancel == true), we
+ * can skip to send cancel. Then this will wait the prior
+ * cancel, or merged into the next cancel rarely if next
+ * cancel was started before waiting done. In any case, this
+ * will be waked up soon or later.
+ */
+ if (!dev->cmd_cancel) {
+ reinit_completion(&dev->cmd_cancel_done);
- dev->out_urb->transfer_buffer = ack_frame;
- dev->out_urb->transfer_buffer_length = sizeof(ack_frame);
- rc = usb_submit_urb(dev->out_urb, GFP_KERNEL);
+ usb_kill_urb(dev->out_urb);
- /* Set the cmd_cancel flag only if the URB has been successfully
- * submitted. It will be reset by the out URB completion callback
- * port100_send_complete().
- */
- dev->cmd_cancel = !rc;
+ dev->out_urb->transfer_buffer = ack_frame;
+ dev->out_urb->transfer_buffer_length = sizeof(ack_frame);
+ rc = usb_submit_urb(dev->out_urb, GFP_KERNEL);
+
+ /*
+ * Set the cmd_cancel flag only if the URB has been
+ * successfully submitted. It will be reset by the out
+ * URB completion callback port100_send_complete().
+ */
+ dev->cmd_cancel = !rc;
+ }
mutex_unlock(&dev->out_urb_lock);
@@ -928,8 +938,8 @@ static void port100_send_complete(struct
struct port100 *dev = urb->context;
if (dev->cmd_cancel) {
+ complete_all(&dev->cmd_cancel_done);
dev->cmd_cancel = false;
- complete(&dev->cmd_cancel_done);
}
switch (urb->status) {
@@ -1543,6 +1553,7 @@ static int port100_probe(struct usb_inte
PORT100_COMM_RF_HEAD_MAX_LEN;
dev->skb_tailroom = PORT100_FRAME_TAIL_LEN;
+ init_completion(&dev->cmd_cancel_done);
INIT_WORK(&dev->cmd_complete_work, port100_wq_cmd_complete);
/* The first thing to do with the Port-100 is to set the command type