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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	llvm@lists.linux.dev, Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org,
	Nathan Chancellor <nathan@kernel.org>,
	Bill Wendling <morbo@google.com>,
	linux-serial@vger.kernel.org,
	Justin Stitt <justinstitt@google.com>,
	Jiri Slaby <jirislaby@kernel.org>
Subject: Re: [PATCH] tty: hvc-iucv: fix function pointer casts
Date: Tue, 13 Feb 2024 13:12:54 -0600	[thread overview]
Message-ID: <20240213191254.GA19790@gate.crashing.org> (raw)
In-Reply-To: <20240213101756.461701-1-arnd@kernel.org>

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

  reply	other threads:[~2024-02-13 19:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-13 10:17 [PATCH] tty: hvc-iucv: fix function pointer casts Arnd Bergmann
2024-02-13 19:12 ` Segher Boessenkool [this message]
2024-02-14  9:46   ` David Laight
2024-02-14 10:37     ` Greg Kroah-Hartman
2024-02-14 12:36       ` Segher Boessenkool
2024-02-14  6:25 ` Jiri Slaby

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