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[4.2.y-ckt,stable] Patch "can: ems_usb: Fix possible tx overflow" has been added to the 4.2.y-ckt tree

Message ID 1457390086-867-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa March 7, 2016, 10:34 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    can: ems_usb: Fix possible tx overflow

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt5.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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

From 872c388274e689efbff9aa443aee80862e48ae07 Mon Sep 17 00:00:00 2001
From: Gerhard Uttenthaler <uttenthaler@ems-wuensche.com>
Date: Tue, 22 Dec 2015 17:29:16 +0100
Subject: can: ems_usb: Fix possible tx overflow

commit 90cfde46586d2286488d8ed636929e936c0c9ab2 upstream.

This patch fixes the problem that more CAN messages could be sent to the
interface as could be send on the CAN bus. This was more likely for slow baud
rates. The sleeping _start_xmit was woken up in the _write_bulk_callback. Under
heavy TX load this produced another bulk transfer without checking the
free_slots variable and hence caused the overflow in the interface.

Signed-off-by: Gerhard Uttenthaler <uttenthaler@ems-wuensche.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/net/can/usb/ems_usb.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--
2.7.0
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Patch

diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c
index 2d39038..66409fe 100644
--- a/drivers/net/can/usb/ems_usb.c
+++ b/drivers/net/can/usb/ems_usb.c
@@ -117,6 +117,9 @@  MODULE_LICENSE("GPL v2");
  */
 #define EMS_USB_ARM7_CLOCK 8000000

+#define CPC_TX_QUEUE_TRIGGER_LOW	25
+#define CPC_TX_QUEUE_TRIGGER_HIGH	35
+
 /*
  * CAN-Message representation in a CPC_MSG. Message object type is
  * CPC_MSG_TYPE_CAN_FRAME or CPC_MSG_TYPE_RTR_FRAME or
@@ -278,6 +281,11 @@  static void ems_usb_read_interrupt_callback(struct urb *urb)
 	switch (urb->status) {
 	case 0:
 		dev->free_slots = dev->intr_in_buffer[1];
+		if(dev->free_slots > CPC_TX_QUEUE_TRIGGER_HIGH){
+			if (netif_queue_stopped(netdev)){
+				netif_wake_queue(netdev);
+			}
+		}
 		break;

 	case -ECONNRESET: /* unlink */
@@ -527,8 +535,6 @@  static void ems_usb_write_bulk_callback(struct urb *urb)
 	/* Release context */
 	context->echo_index = MAX_TX_URBS;

-	if (netif_queue_stopped(netdev))
-		netif_wake_queue(netdev);
 }

 /*
@@ -588,7 +594,7 @@  static int ems_usb_start(struct ems_usb *dev)
 	int err, i;

 	dev->intr_in_buffer[0] = 0;
-	dev->free_slots = 15; /* initial size */
+	dev->free_slots = 50; /* initial size */

 	for (i = 0; i < MAX_RX_URBS; i++) {
 		struct urb *urb = NULL;
@@ -836,7 +842,7 @@  static netdev_tx_t ems_usb_start_xmit(struct sk_buff *skb, struct net_device *ne

 		/* Slow down tx path */
 		if (atomic_read(&dev->active_tx_urbs) >= MAX_TX_URBS ||
-		    dev->free_slots < 5) {
+		    dev->free_slots < CPC_TX_QUEUE_TRIGGER_LOW) {
 			netif_stop_queue(netdev);
 		}
 	}