[PATCH] can: rockchip_canfd: fix return type of rkcanfd_start_xmit()

[Marc Kleine-Budde]

On 09.09.2024 09:44:48, Simon Horman wrote:
> On Fri, Sep 06, 2024 at 01:26:41PM -0700, Nathan Chancellor wrote:
> > With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> > indirect call targets are validated against the expected function
> > pointer prototype to make sure the call target is valid to help mitigate
> > ROP attacks. If they are not identical, there is a failure at run time,
> > which manifests as either a kernel panic or thread getting killed. A
> > warning in clang aims to catch these at compile time, which reveals:
> > 
> >   drivers/net/can/rockchip/rockchip_canfd-core.c:770:20: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
> >     770 |         .ndo_start_xmit = rkcanfd_start_xmit,
> >         |                           ^~~~~~~~~~~~~~~~~~
> > 
> > ->ndo_start_xmit() in 'struct net_device_ops' expects a return type of
> > 'netdev_tx_t', not 'int' (although the types are ABI compatible). Adjust
> > the return type of rkcanfd_start_xmit() to match the prototype's to
> > resolve the warning.
> > 
> > Fixes: ff60bfbaf67f ("can: rockchip_canfd: add driver for Rockchip CAN-FD controller")
> > Signed-off-by: Nathan Chancellor <nathan at kernel.org>
> 
> Thanks, I was able to reproduce this problem at build time
> and that your patch addresses it.

FTR: the default clang in Debian unstable, clang-16.0.6 doesn't support
this. With clang-20 from experimental it works, haven't checked older
versions, though.

regards,
Marc

-- 
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