linux-kernel - Re: [PATCH] LLVMLinux: Remove warning about returning an uninitialized variable

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Message-ID: <5339E7CB.2080001@converseincode.com>
Date:	Mon, 31 Mar 2014 15:10:19 -0700
From:	Behan Webster <behanw@...verseincode.com>
To:	"H. Peter Anvin" <hpa@...or.com>, arnd@...db.de
CC:	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
	dwmw2@...radead.org, pageexec@...email.hu,
	Mark Charlebois <charlebm@...il.com>
Subject: Re: [PATCH] LLVMLinux: Remove warning about returning an uninitialized
 variable

On 03/31/14 13:52, H. Peter Anvin wrote:
> On 03/21/2014 11:38 PM, behanw@...verseincode.com wrote:
>> From: Behan Webster <behanw@...verseincode.com>
>>
>> Fix uninitialized return code in default case in cmpxchg-local.h
>>
>> This patch fixes the code to prevent an uninitialized return value that is detected
>> when compiling with clang. The bug produces numerous warnings when compiling the
>> Linux kernel with clang.
>>
>> Signed-off-by: Behan Webster <behanw@...verseincode.com>
>> Signed-off-by: Mark Charlebois <charlebm@...il.com>
>> ---
>>   include/asm-generic/cmpxchg-local.h | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h
>> index d8d4c89..4c41bb8 100644
>> --- a/include/asm-generic/cmpxchg-local.h
>> +++ b/include/asm-generic/cmpxchg-local.h
>> @@ -41,6 +41,7 @@ static inline unsigned long __cmpxchg_local_generic(volatile void *ptr,
>>   		break;
>>   	default:
>>   		wrong_size_cmpxchg(ptr);
>> +		prev = 0;
>>   	}
>>   	raw_local_irq_restore(flags);
>>   	return prev;
>>
> Shouldn't this be a build time assert (__compiletime_error())?
I changed it to a __noreturn on wrong_size_cmpxchg thanks to James 
Bottomley.

Which would be better?

Behan

-- 
Behan Webster
behanw@...verseincode.com

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