linux-kernel - Re: [PATCH] agp: amd64: remove unneeded initialization

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Date:   Wed, 28 Oct 2020 07:02:35 -0700
From:   Tom Rix <trix@...hat.com>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        David Airlie <airlied@...ux.ie>
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-safety@...ts.elisa.tech
Subject: Re: [PATCH] agp: amd64: remove unneeded initialization


On 10/28/20 6:31 AM, Lukas Bulwahn wrote:
> make clang-analyzer on x86_64 defconfig caught my attention with:
>
>   drivers/char/agp/amd64-agp.c:336:2: warning: \
>   Value stored to 'i' is never read [clang-analyzer-deadcode.DeadStores]
>           i = 0;
>           ^
>
> Remove this unneeded initialization to make clang-analyzer happy.
>
> Commit a32073bffc65 ("x86_64: Clean and enhance up K8 northbridge access
> code") refactored cache_nbs() and introduced this unneeded dead-store
> initialization.
>
> As compilers will detect this unneeded assignment and optimize this anyway,
> the resulting binary is identical before and after this change.
>
> No functional change. No change in binary code.
>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
> ---
> applies cleanly on current master and next-20201028
>
> David, please pick this minor non-urgent clean-up patch.
>
>  drivers/char/agp/amd64-agp.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c
> index b40edae32817..0413b3136541 100644
> --- a/drivers/char/agp/amd64-agp.c
> +++ b/drivers/char/agp/amd64-agp.c
> @@ -333,7 +333,6 @@ static int cache_nbs(struct pci_dev *pdev, u32 cap_ptr)
>  	if (!amd_nb_has_feature(AMD_NB_GART))
>  		return -ENODEV;
>  
> -	i = 0;
>  	for (i = 0; i < amd_nb_num(); i++) {
>  		struct pci_dev *dev = node_to_amd_nb(i)->misc;
>  		if (fix_northbridge(dev, pdev, cap_ptr) < 0) {

Looks ok to me.

Reviewed-by: Tom Rix <trix@...hat.com>