65a67792e3
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 <davem@davemloft.net>
Signed-off-by: Du Cheng <ducheng2@gmail.com>
Link: https://lore.kernel.org/r/20210503115736.2104747-20-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.