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Message-ID: <57d72e2ccc8245fe99982613a11c461c@AcuMS.aculab.com>
Date: Wed, 14 Feb 2024 09:46:33 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Segher Boessenkool' <segher@...nel.crashing.org>, Arnd Bergmann
<arnd@...nel.org>
CC: "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>, "Arnd
Bergmann" <arnd@...db.de>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"llvm@...ts.linux.dev" <llvm@...ts.linux.dev>, Nick Desaulniers
<ndesaulniers@...gle.com>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, Nathan Chancellor <nathan@...nel.org>, "Bill
Wendling" <morbo@...gle.com>, "linux-serial@...r.kernel.org"
<linux-serial@...r.kernel.org>, Justin Stitt <justinstitt@...gle.com>, "Jiri
Slaby" <jirislaby@...nel.org>
Subject: RE: [PATCH] tty: hvc-iucv: fix function pointer casts
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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