linux-kernel - Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to 64 bits in X86

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Message-ID: <4A0C2614.4010803@zytor.com>
Date:	Thu, 14 May 2009 07:09:24 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Sheng Yang <sheng@...ux.intel.com>
CC:	linux-kernel@...r.kernel.org, linux-mm <linux-mm@...ck.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] x86: Extend test_and_set_bit() test_and_clean_bit() to
 64 bits in X86_64

Sheng Yang wrote:
> 
> Yeah, this one also works well(lightly tested). :)
> 
> But one thing should be noticed that, bit ops recognized the input as signed. 
> According to SDM 2A 3.1.1.7 Operation Section, Bit(BitBase, BitOffset) can 
> accept BitOffset as negative value, then search backward... Well, I indeed 
> don't know when we need this, but I think keep signed here should be better...
> 

Urk, you're right.  How daft.  I had preferred to switch it to unsigned
long to match MIPS and SPARC, but that probably is a good reason to
leave it signed.  Pain.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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