linux-kernel - Re: [PATCH v2 2/3] powerpc: get hugetlbpage handling more generic

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Date:   Mon, 19 Sep 2016 20:36:47 +0200
From:   christophe leroy <christophe.leroy@....fr>
To:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Scott Wood <oss@...error.net>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2 2/3] powerpc: get hugetlbpage handling more generic



Le 19/09/2016 à 07:50, Aneesh Kumar K.V a écrit :
>
> Christophe Leroy <christophe.leroy@....fr> writes:
>> +#else
>> +static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
>> +{
>> +	BUG();
>> +}
>> +
>>  #endif
>
>
> I was expecting that BUG will get removed in the next patch. But I don't
> see it in the next patch. Considering
>
> @@ -475,11 +453,10 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif
>         for (i = 0; i < num_hugepd; i++, hpdp++)
>                 hpdp->pd = 0;
>
> -#ifdef CONFIG_PPC_FSL_BOOK3E
> -	hugepd_free(tlb, hugepte);
> -#else
> -	pgtable_free_tlb(tlb, hugepte, pdshift - shift);
> -#endif
> +	if (shift >= pdshift)
> +		hugepd_free(tlb, hugepte);
> +	else
> +		pgtable_free_tlb(tlb, hugepte, pdshift - shift);
>  }
>
> What is that I am missing ?
>

Previously, call to hugepd_free() was compiled only when #ifdef 
CONFIG_PPC_FSL_BOOK3E
Now, it is compiled at all time, but it should never be called if not 
CONFIG_PPC_FSL_BOOK3E because we always have shift < pdshift in that case.
Then the function needs to be defined anyway but should never be called. 
Should I just define it static inline {} ?

Christophe

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