From: Helge Deller <deller@gmx.de>
To: Gao Xiang <xiang@kernel.org>, linux-parisc@vger.kernel.org
Cc: Liam Beguin <liambeguin@gmail.com>,
linux-kernel@vger.kernel.org, Gao Xiang <hsiangkao@redhat.com>
Subject: Re: [PATCH] parisc: avoid a warning on u8 cast for cmpxchg on u8 pointers
Date: Tue, 6 Apr 2021 12:08:55 +0200 [thread overview]
Message-ID: <ee2016b1-926e-93b1-ba92-d5f4975f06c9@gmx.de> (raw)
In-Reply-To: <20210406045929.30331-1-xiang@kernel.org>
On 4/6/21 6:59 AM, Gao Xiang wrote:
> From: Gao Xiang <hsiangkao@redhat.com>
>
> commit b344d6a83d01 ("parisc: add support for cmpxchg on u8 pointers")
> can generate a sparse warningi ("cast truncates bits from constant
> value"), which has been reported several times [1] [2] [3].
>
> The original code worked as expected, but anyway, let silence such
> sparse warning as what others did [4].
>
> [1] https://lore.kernel.org/r/202104061220.nRMBwCXw-lkp@intel.com
> [2] https://lore.kernel.org/r/202012291914.T5Agcn99-lkp@intel.com
> [3] https://lore.kernel.org/r/202008210829.KVwn7Xeh%25lkp@intel.com
> [4] https://lore.kernel.org/r/20210315131512.133720-2-jacopo+renesas@jmondi.org
> Cc: Liam Beguin <liambeguin@gmail.com>
> Cc: Helge Deller <deller@gmx.de>
> Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
applied to the parisc for-next git tree.
(I fixed up the typo above too)
Thanks!
Helge
> ---
> arch/parisc/include/asm/cmpxchg.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/parisc/include/asm/cmpxchg.h b/arch/parisc/include/asm/cmpxchg.h
> index cf5ee9b0b393..84ee232278a6 100644
> --- a/arch/parisc/include/asm/cmpxchg.h
> +++ b/arch/parisc/include/asm/cmpxchg.h
> @@ -72,7 +72,7 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
> #endif
> case 4: return __cmpxchg_u32((unsigned int *)ptr,
> (unsigned int)old, (unsigned int)new_);
> - case 1: return __cmpxchg_u8((u8 *)ptr, (u8)old, (u8)new_);
> + case 1: return __cmpxchg_u8((u8 *)ptr, old & 0xff, new_ & 0xff);
> }
> __cmpxchg_called_with_bad_pointer();
> return old;
>
next prev parent reply other threads:[~2021-04-06 10:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 4:59 [PATCH] parisc: avoid a warning on u8 cast for cmpxchg on u8 pointers Gao Xiang
2021-04-06 8:49 ` Rolf Eike Beer
2021-04-06 10:08 ` Helge Deller [this message]
2021-04-06 10:57 ` Gao Xiang
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