From: maobibo <maobibo@loongson.cn>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Thomas Bogendoerfer" <tsbogend@alpha.franken.de>,
"Jiaxun Yang" <jiaxun.yang@flygoat.com>,
"Huacai Chen" <chenhc@lemote.com>,
"Paul Burton" <paulburton@kernel.org>,
"Dmitry Korotin" <dkorotin@wavecomp.com>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Stafford Horne" <shorne@gmail.com>,
"Steven Price" <steven.price@arm.com>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
"Mike Rapoport" <rppt@linux.ibm.com>,
"Sergei Shtylyov" <sergei.shtylyov@cogentembedded.com>,
"Maciej W. Rozycki" <macro@wdc.com>,
linux-mm@kvack.org, "David Hildenbrand" <david@redhat.com>
Subject: Re: [PATCH v6 1/4] MIPS: Do not flush tlb page when updating PTE entry
Date: Wed, 27 May 2020 09:06:22 +0800 [thread overview]
Message-ID: <a7263f61-2159-5831-8afd-bc38e7e1cb6b@loongson.cn> (raw)
In-Reply-To: <20200525144241.f0e55183a846607cdbb0d819@linux-foundation.org>
On 05/26/2020 05:42 AM, Andrew Morton wrote:
> On Mon, 25 May 2020 10:52:37 +0800 Bibo Mao <maobibo@loongson.cn> wrote:
>
>> It is not necessary to flush tlb page on all CPUs if suitable PTE
>> entry exists already during page fault handling, just updating
>> TLB is fine.
>>
>> Here redefine flush_tlb_fix_spurious_fault as empty on MIPS system.
>>
>> ...
>>
>> --- a/arch/mips/include/asm/pgtable.h
>> +++ b/arch/mips/include/asm/pgtable.h
>> @@ -478,6 +478,8 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
>> return __pgprot(prot);
>> }
>>
>> +#define flush_tlb_fix_spurious_fault(vma, address) do { } while (0)
>> +
>
> static inline C would be preferred, if that works. For a number of reasons:
>
> - looks nicer
>
> - more likely to get a code comment (for some reason)
>
> - adds typechecking. So right now a MIPS developer could do
>
> struct wibble a;
> struct wobble b;
>
> flush_tlb_fix_spurious_fault(&a, &b);
>
> and there would be no compiler warning. Then the code gets merged
> upstream and in come the embarrassing emails!
>
> - avoids unused-var warnings
>
> foo()
> {
> struct address_space a;
> struct vm_area_struct v;
>
> flush_tlb_fix_spurious_fault(&v, &a);
> }
>
> will generate unused-variable warnings if
> flush_tlb_fix_spurious_fault() is a macro. Making
> flush_tlb_fix_spurious_fault() inlined C prevents this.
>
Sure, I will modify this and send another version.
prev parent reply other threads:[~2020-05-27 1:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 2:52 [PATCH v6 1/4] MIPS: Do not flush tlb page when updating PTE entry Bibo Mao
2020-05-25 2:52 ` [PATCH v6 2/4] mm/memory.c: Update local TLB if PTE entry exists Bibo Mao
2020-05-25 21:43 ` Andrew Morton
2020-05-25 2:52 ` [PATCH v6 3/4] mm/memory.c: Add memory read privilege on page fault handling Bibo Mao
2020-05-25 21:44 ` Andrew Morton
2020-05-27 1:05 ` maobibo
2020-05-27 7:10 ` Thomas Bogendoerfer
2020-05-25 2:52 ` [PATCH v6 4/4] MIPS: mm: add page valid judgement in function pte_modify Bibo Mao
2020-05-25 8:12 ` [PATCH v6 1/4] MIPS: Do not flush tlb page when updating PTE entry Sergei Shtylyov
2020-05-25 8:31 ` Sergei Shtylyov
2020-05-27 1:07 ` maobibo
2020-05-25 21:42 ` Andrew Morton
2020-05-27 1:06 ` maobibo [this message]
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