linux-kernel - Re: [RFC PATCH 6/6] pkeys: Change mm_pkey

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Message-ID: <af035c24-36f6-7d55-5be7-b52cfe26e2c6@csgroup.eu>
Date:   Mon, 13 Jun 2022 09:17:06 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     "ira.weiny@...el.com" <ira.weiny@...el.com>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
        Sohil Mehta <sohil.mehta@...el.com>
Subject: Re: [RFC PATCH 6/6] pkeys: Change mm_pkey_free() to void



Le 11/06/2022 à 01:35, ira.weiny@...el.com a écrit :
> From: Ira Weiny <ira.weiny@...el.com>
> 
> Now that the pkey arch support is no longer checked in mm_pkey_free()
> there is no reason to have it return int.

Right, I see this is doing what I commented in previous patch.


> 
> Change the return value to void.
> 
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>
> Suggested-by: Sohil Mehta <sohil.mehta@...el.com>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
>   arch/powerpc/include/asm/pkeys.h | 4 +---
>   arch/x86/include/asm/pkeys.h     | 4 +---
>   include/linux/pkeys.h            | 5 +----
>   mm/mprotect.c                    | 6 ++++--
>   4 files changed, 7 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> index e96aa91f817b..4d01a48ab941 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -105,11 +105,9 @@ static inline int mm_pkey_alloc(struct mm_struct *mm)
>   	return ret;
>   }
>   
> -static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
> +static inline void mm_pkey_free(struct mm_struct *mm, int pkey)
>   {
>   	__mm_pkey_free(mm, pkey);
> -
> -	return 0;
>   }
>   
>   /*
> diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
> index da02737cc4d1..1f408f46fa9a 100644
> --- a/arch/x86/include/asm/pkeys.h
> +++ b/arch/x86/include/asm/pkeys.h
> @@ -105,11 +105,9 @@ int mm_pkey_alloc(struct mm_struct *mm)
>   }
>   
>   static inline
> -int mm_pkey_free(struct mm_struct *mm, int pkey)
> +void mm_pkey_free(struct mm_struct *mm, int pkey)
>   {
>   	mm_set_pkey_free(mm, pkey);
> -
> -	return 0;
>   }
>   
>   static inline int vma_pkey(struct vm_area_struct *vma)
> diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
> index 86be8bf27b41..bf98c50a3437 100644
> --- a/include/linux/pkeys.h
> +++ b/include/linux/pkeys.h
> @@ -30,10 +30,7 @@ static inline int mm_pkey_alloc(struct mm_struct *mm)
>   	return -1;
>   }
>   
> -static inline int mm_pkey_free(struct mm_struct *mm, int pkey)
> -{
> -	return -EINVAL;
> -}
> +static inline void mm_pkey_free(struct mm_struct *mm, int pkey) { }
>   
>   static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
>   			unsigned long init_val)
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 41458e729c27..e872bdd2e228 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -809,8 +809,10 @@ SYSCALL_DEFINE1(pkey_free, int, pkey)
>   		return ret;
>   
>   	mmap_write_lock(current->mm);
> -	if (mm_pkey_is_allocated(current->mm, pkey))
> -		ret = mm_pkey_free(current->mm, pkey);
> +	if (mm_pkey_is_allocated(current->mm, pkey)) {
> +		mm_pkey_free(current->mm, pkey);
> +		ret = 0;
> +	}

Or you could have ret = 0 by default and do

	if (mm_pkey_is_allocated(current->mm, pkey))
		mm_pkey_free(current->mm, pkey);
	else
		ret = -EINVAL;

>   	mmap_write_unlock(current->mm);
>   
>   	/*