linux-kernel - Re: [PATCH v5 5/7] x86/tlb: add tlb_flushall

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Date:	Wed, 16 May 2012 10:55:10 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Alex Shi <alex.shi@...el.com>
CC:	tglx@...utronix.de, mingo@...hat.com, arnd@...db.de,
	rostedt@...dmis.org, fweisbec@...il.com, jeremy@...p.org,
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Subject: Re: [PATCH v5 5/7] x86/tlb: add tlb_flushall_shift for specific CPU

On 05/15/2012 11:49 PM, Alex Shi wrote:
> +	if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
> +			|| tlb_flushall_shift == (u16)TLB_FLUSH_ALL) {

I asked for you to fold the cpu_has_invlpg test into tlb_flushall_shift.
 Also, (u16)TLB_FLUSH_ALL really is hit up with the ugly stick... why on
earth is this u16?  It's a bit shift, so it can't be bigger than 6 bits
anyway... and if you want to be able to use -1 as a sentinel you might
as well make it a signed value and use < 0 or == -1 as the test.

Am I missing something really fundamental here?

	-hpa

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

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