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Date: Thu, 06 Jul 2006 16:27:55 -0400
From: Mark Lord <lkml@rtr.ca>
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To: Linus Torvalds <torvalds@osdl.org>
Cc: Chris Friesen <cfriesen@nortel.com>,
       Arjan van de Ven <arjan@infradead.org>,
       "linux-os (Dick Johnson)" <linux-os@analogic.com>,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [patch] spinlocks: remove 'volatile'
References: <20060705114630.GA3134@elte.hu> <20060705101059.66a762bf.akpm@osdl.org> <20060705193551.GA13070@elte.hu> <20060705131824.52fa20ec.akpm@osdl.org> <Pine.LNX.4.64.0607051332430.12404@g5.osdl.org> <20060705204727.GA16615@elte.hu> <Pine.LNX.4.64.0607051411460.12404@g5.osdl.org> <20060705214502.GA27597@elte.hu> <Pine.LNX.4.64.0607051458200.12404@g5.osdl.org> <Pine.LNX.4.64.0607051555140.12404@g5.osdl.org> <20060706081639.GA24179@elte.hu> <Pine.LNX.4.61.0607060756050.8312@chaos.analogic.com> <1152187268.3084.29.camel@laptopd505.fenrus.org> <44AD5357.4000100@rtr.ca> <Pine.LNX.4.64.0607061213560.3869@g5.osdl.org> <44AD658A.5070005@nortel.com> <Pine.LNX.4.64.0607061257130.3869@g5.osdl.org>
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Linus Torvalds wrote:
> 
> On Thu, 6 Jul 2006, Chris Friesen wrote:
>> The C standard requires the use of volatile for signal handlers and setjmp.
> 
> Actually, the C standard requires "sigatomic_t".

That's sig_atomic_t, which simply guarantees that the data item
can be read or written indivisibly with respect to signal handlers.

The standard goes on to suggest using it in combination with volatile
as needed.

Cheers