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

David Laight
2024-02-14T09:46:58Z

From: Segher Boessenkool
> Sent: 13 February 2024 19:13
>
> 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.

But it will get called using the wrong type.
And (is it) fine-ibt will reject the incorrect call.

Has clang/gcc added an attribute to 'seed' the ibt hash yet?
So that functions that are void (*)(void) can be separated?

David

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