From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: [patch 07/12] can: c_can: Provide protection in the xmit path Date: Tue, 18 Mar 2014 17:19:12 -0000 Message-ID: <20140318171127.306582080@linutronix.de> References: <20140318171007.528610837@linutronix.de> Return-path: Content-Disposition: inline; filename=can-c_can-fix-xmit.patch Sender: linux-kernel-owner@vger.kernel.org To: LKML Cc: Wolfgang Grandegger , Marc Kleine-Budde , Markus Pargmann , Benedikt Spranger , linux-can@vger.kernel.org, netdev@vger.kernel.org List-Id: linux-can.vger.kernel.org The network core does not serialize the access to the hardware. The xmit related code lets the following happen: CPU0 CPU1 interrupt() do_poll() c_can_do_tx() Fiddle with HW and xmit() internal data Fiddle with HW and internal data due the complete lack of serialization. Add proper locking. Signed-off-by: Thomas Gleixner --- drivers/net/can/c_can/c_can.c | 9 ++++++++- drivers/net/can/c_can/c_can.h | 1 + 2 files changed, 9 insertions(+), 1 deletion(-) Index: linux/drivers/net/can/c_can/c_can.c =================================================================== --- linux.orig/drivers/net/can/c_can/c_can.c +++ linux/drivers/net/can/c_can/c_can.c @@ -549,6 +549,7 @@ static netdev_tx_t c_can_start_xmit(stru if (can_dropped_invalid_skb(dev, skb)) return NETDEV_TX_OK; + spin_lock_bh(&priv->xmit_lock); msg_obj_no = get_tx_next_msg_obj(priv); /* prepare message object for transmission */ @@ -563,6 +564,7 @@ static netdev_tx_t c_can_start_xmit(stru if (c_can_is_next_tx_obj_busy(priv, get_tx_next_msg_obj(priv)) || (priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) == 0) netif_stop_queue(dev); + spin_unlock_bh(&priv->xmit_lock); return NETDEV_TX_OK; } @@ -778,7 +780,9 @@ static void c_can_do_tx(struct net_devic struct c_can_priv *priv = netdev_priv(dev); struct net_device_stats *stats = &dev->stats; - for (/* nix */; (priv->tx_next - priv->tx_echo) > 0; priv->tx_echo++) { + spin_lock_bh(&priv->xmit_lock); + + for (; (priv->tx_next - priv->tx_echo) > 0; priv->tx_echo++) { msg_obj_no = get_tx_echo_msg_obj(priv); val = c_can_read_reg32(priv, C_CAN_TXRQST1_REG); if (!(val & (1 << (msg_obj_no - 1)))) { @@ -800,6 +804,8 @@ static void c_can_do_tx(struct net_devic if (((priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) != 0) || ((priv->tx_echo & C_CAN_NEXT_MSG_OBJ_MASK) == 0)) netif_wake_queue(dev); + + spin_unlock_bh(&priv->xmit_lock); } /* @@ -1250,6 +1256,7 @@ struct net_device *alloc_c_can_dev(void) return NULL; priv = netdev_priv(dev); + spin_lock_init(&priv->xmit_lock); netif_napi_add(dev, &priv->napi, c_can_poll, C_CAN_NAPI_WEIGHT); priv->dev = dev; Index: linux/drivers/net/can/c_can/c_can.h =================================================================== --- linux.orig/drivers/net/can/c_can/c_can.h +++ linux/drivers/net/can/c_can/c_can.h @@ -156,6 +156,7 @@ struct c_can_priv { struct napi_struct napi; struct net_device *dev; struct device *device; + spinlock_t xmit_lock; int tx_object; int current_status; int last_status;