linux-kernel - Re: [PATCH] blk-throttle: don't call xchg on bool

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Message-ID: <m3vcz0ra1l.fsf@linux-m68k.org>
Date:	Wed, 30 Mar 2011 15:51:34 +0200
From:	Andreas Schwab <schwab@...ux-m68k.org>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org, jaxboe@...ionio.com,
	paulmck@...ux.vnet.ibm.com, oleg@...hat.com
Subject: Re: [PATCH] blk-throttle: don't call xchg on bool

Vivek Goyal <vgoyal@...hat.com> writes:

> Which arch creates the problem and what's the issue here if data type
> is smaller than 32bit?

Just look at the various implementations in arch/*/include/asm/system.h:

- arm: supports only one and 4 byte xchg
- avr32: supports only 4 byte xchg
- frv: supports only 4 byte xchg
- m32r: SMP supports only 4 byte xchg
- microblaze: supports only one and 4 byte xchg

etc.

> Is it a compile time warning?

Most implementations turn the use of xchg with a bad pointer into a link
error.

Andreas.

-- 
Andreas Schwab, schwab@...ux-m68k.org
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