linux-kernel - Re: [PATCH FIXED] x86: use flush_tlb_others to implement flush_tlb

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Date:	Wed, 13 May 2009 10:36:22 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Ian Campbell <Ian.Campbell@...citrix.com>
CC:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	the arch/x86 maintainers <x86@...nel.org>,
	Xen-devel <xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH FIXED] x86: use flush_tlb_others to implement	flush_tlb_all

Ian Campbell wrote:
> get_cpu() returns smp_processor_id() so wouldn't this be more normally
> written as:
> 	/* flush_tlb_others expects preempt to be disabled */
> 	unsigned long cpu = get_cpu();
> 	[....]
> 	if ([....] == TLBSTATE_LAZY)
> 		leave_mm(cpu)
> 	put_cpu();
>   

Quite so.  In theory gcc should be able to CSE smp_processor_id(), but 
the intent of get_cpu() is that you use its return value...

    J
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