From 045d2da9950528ec72f06fbb1cb2b981c2541ba0 Mon Sep 17 00:00:00 2001 From: Gerhard Uttenthaler Date: Tue, 22 Dec 2015 17:29:16 +0100 Subject: [PATCH] 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 Signed-off-by: Marc Kleine-Budde Signed-off-by: Ben Hutchings --- drivers/net/can/usb/ems_usb.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c index a72c7bfb4090..3b8c4da11f3e 100644 --- a/drivers/net/can/usb/ems_usb.c +++ b/drivers/net/can/usb/ems_usb.c @@ -118,6 +118,9 @@ 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 @@ -280,6 +283,11 @@ 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 */ @@ -535,8 +543,6 @@ 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); } /* @@ -596,7 +602,7 @@ 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; @@ -858,7 +864,7 @@ 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); } } -- 2.39.2