Re: [PATCH] tty: hvc-iucv: fix function pointer casts

Segher Boessenkool
2024-02-13T19:42:50Z

On Tue, Feb 13, 2024 at 11:17:49AM +0100, Arnd Bergmann wrote:
> clang warns about explicitly casting between incompatible function
> pointers:
>
> drivers/tty/hvc/hvc_iucv.c:1100:23: error: cast from 'void (*)(const void *)' to 'void (*)(struct device *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
> 1100 | priv->dev->release = (void (*)(struct device *)) kfree;
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Such a cast of course is explicitly allowed by 6.3.2.3/8, only calling a
function using a non-compatible type is UB. This warning message is
quite misleading. Doubly so because of the -Werror, as always.

Your proposed new code of course is nice and simple (albeit a bit bigger
than it was before, both source and binary). Such is life ;-)

Segher