linux-kernel - Re: [PATCH] x86: efi: Replace GFP_ATOMIC with GFP_KERNEL in efi_query_variable

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Date:   Tue, 13 Feb 2018 19:07:08 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     matt@...eblueprint.co.uk, ard.biesheuvel@...aro.org,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: efi: Replace GFP_ATOMIC with GFP_KERNEL in
 efi_query_variable_store


* Jia-Ju Bai <baijiaju1990@...il.com> wrote:

> The function kzalloc here is not called in atomic context.
> If nonblocking in efi_query_variable_store is true, 
> namely it is in atomic context, efi_query_variable_store will return before
> this kzalloc is called.
> Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
> 
> This is found by a static analysis tool named DCNS written by myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
> ---
>  arch/x86/platform/efi/quirks.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index 8a99a2e..b6dcb52 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -177,7 +177,7 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size,
>  		 * that by attempting to use more space than is available.
>  		 */
>  		unsigned long dummy_size = remaining_size + 1024;
> -		void *dummy = kzalloc(dummy_size, GFP_ATOMIC);
> +		void *dummy = kzalloc(dummy_size, GFP_KERNEL);

Looks good to me!

Reviewed-by: Ingo Molnar <mingo@...nel.org>

Thanks,

	Ingo