From 65a67792e3416f7c5d7daa47d99334cbb19a7449 Mon Sep 17 00:00:00 2001 From: Du Cheng Date: Mon, 3 May 2021 13:56:46 +0200 Subject: net: caif: remove BUG_ON(dev == NULL) in caif_xmit The condition of dev == NULL is impossible in caif_xmit(), hence it is for the removal. Explanation: The static caif_xmit() is only called upon via a function pointer `ndo_start_xmit` defined in include/linux/netdevice.h: ``` struct net_device_ops { ... netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev); ... } ``` The exhausive list of call points are: ``` drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c dev->netdev_ops->ndo_start_xmit(skb, dev); ^ ^ drivers/infiniband/ulp/opa_vnic/opa_vnic_netdev.c struct opa_vnic_adapter *adapter = opa_vnic_priv(netdev); ^ ^ return adapter->rn_ops->ndo_start_xmit(skb, netdev); // adapter would crash first ^ ^ drivers/usb/gadget/function/f_ncm.c ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev); ^ ^ include/linux/netdevice.h static inline netdev_tx_t __netdev_start_xmit(... { return ops->ndo_start_xmit(skb, dev); ^ } const struct net_device_ops *ops = dev->netdev_ops; ^ rc = __netdev_start_xmit(ops, skb, dev, more); ^ ``` In each of the enumerated scenarios, it is impossible for the NULL-valued dev to reach the caif_xmit() without crashing the kernel earlier, therefore `BUG_ON(dev == NULL)` is rather useless, hence the removal. Cc: David S. Miller Signed-off-by: Du Cheng Link: https://lore.kernel.org/r/20210503115736.2104747-20-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman --- drivers/net/caif/caif_serial.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/net/caif/caif_serial.c') diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c index a7f51eb58915..d17482395a4d 100644 --- a/drivers/net/caif/caif_serial.c +++ b/drivers/net/caif/caif_serial.c @@ -269,7 +269,6 @@ static netdev_tx_t caif_xmit(struct sk_buff *skb, struct net_device *dev) { struct ser_device *ser; - BUG_ON(dev == NULL); ser = netdev_priv(dev); /* Send flow off once, on high water mark */ -- cgit v1.2.3