linux-kernel - RE: [PATCH v2 1/6] ia64, processor: fix -Wincompatible-pointer-types in ia64_get

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Date:   Fri, 10 Jun 2022 12:18:03 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Alexander Lobakin' <alexandr.lobakin@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Yury Norov <yury.norov@...il.com>
CC:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Matt Turner <mattst88@...il.com>,
        Brian Cain <bcain@...cinc.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        "Yoshinori Sato" <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        Kees Cook <keescook@...omium.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Marco Elver <elver@...gle.com>, Borislav Petkov <bp@...e.de>,
        Tony Luck <tony.luck@...el.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "linux-alpha@...r.kernel.org" <linux-alpha@...r.kernel.org>,
        "linux-hexagon@...r.kernel.org" <linux-hexagon@...r.kernel.org>,
        "linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
        "linux-m68k@...ts.linux-m68k.org" <linux-m68k@...ts.linux-m68k.org>,
        "linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
        "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        kernel test robot <lkp@...el.com>
Subject: RE: [PATCH v2 1/6] ia64, processor: fix -Wincompatible-pointer-types
 in ia64_get_irr()

From: Alexander Lobakin
> Sent: 10 June 2022 12:34
> 
> test_bit(), as any other bitmap op, takes `unsigned long *` as a
> second argument (pointer to the actual bitmap), as any bitmap
> itself is an array of unsigned longs. However, the ia64_get_irr()
> code passes a ref to `u64` as a second argument.
> This works with the ia64 bitops implementation due to that they
> have `void *` as the second argument and then cast it later on.
> This works with the bitmap API itself due to that `unsigned long`
> has the same size on ia64 as `u64` (`unsigned long long`), but
> from the compiler PoV those two are different.
> Define @irr as `unsigned long` to fix that. That implies no
> functional changes. Has been hidden for 16 years!

Wouldn't it be better to just test the bit?
As in:
	return irr & (1ull << bit);

    David

> 
> Fixes: a58786917ce2 ("[IA64] avoid broken SAL_CACHE_FLUSH implementations")
> Cc: stable@...r.kernel.org # 2.6.16+
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Alexander Lobakin <alexandr.lobakin@...el.com>
> ---
>  arch/ia64/include/asm/processor.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/ia64/include/asm/processor.h b/arch/ia64/include/asm/processor.h
> index 7cbce290f4e5..757c2f6d8d4b 100644
> --- a/arch/ia64/include/asm/processor.h
> +++ b/arch/ia64/include/asm/processor.h
> @@ -538,7 +538,7 @@ ia64_get_irr(unsigned int vector)
>  {
>  	unsigned int reg = vector / 64;
>  	unsigned int bit = vector % 64;
> -	u64 irr;
> +	unsigned long irr;
> 
>  	switch (reg) {
>  	case 0: irr = ia64_getreg(_IA64_REG_CR_IRR0); break;
> --
> 2.36.1

-
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