linux-kernel - Re: [PATCH] wifi: mt76: mt7996: remove redundant NULL check in mt7996_msdu_page_get_from

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Message-ID: <aPoqiioo6kUZ0kbY@lore-desk>
Date: Thu, 23 Oct 2025 15:15:54 +0200
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: Rakuram Eswaran <rakuram.e96@...il.com>
Cc: Felix Fietkau <nbd@....name>, Ryder Lee <ryder.lee@...iatek.com>,
	Shayne Chen <shayne.chen@...iatek.com>,
	Sean Wang <sean.wang@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Rex Lu <rex.lu@...iatek.com>, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org, david.hunter.linux@...il.com,
	khalid@...nel.org, skhan@...uxfoundation.org,
	linux-kernel-mentees@...ts.linux.dev,
	kernel test robot <lkp@...el.com>,
	Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH] wifi: mt76: mt7996: remove redundant NULL check in
 mt7996_msdu_page_get_from_cache()

> Smatch reported a warning that the NULL check on `p` in
> `mt7996_msdu_page_get_from_cache()` is redundant:
> 
>   drivers/net/wireless/mediatek/mt76/mt7996/mac.c:1651
>   mt7996_msdu_page_get_from_cache() warn: can 'p' even be NULL?
> 
> The function first checks `list_empty(&dev->wed_rro.page_cache)` before
> calling `list_first_entry()`. When the list is not empty,
> `list_first_entry()` always returns a valid pointer and can never be NULL.
> 
> Hence, the `if (p)` condition is unnecessary. Removing it cleans up the
> code.

Hi Rakuram,

this issue has been already fixed here:
https://patchwork.kernel.org/project/linux-wireless/patch/20251014-mt7996_msdu_page_get_from_cache-remove-null-ptr-check-v1-1-fbeb7881e192@kernel.org/

Regards,
Lorenzo

> 
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/r/202510100155.MS0IXhzm-lkp@intel.com/
> Signed-off-by: Rakuram Eswaran <rakuram.e96@...il.com>
> ---
>  drivers/net/wireless/mediatek/mt76/mt7996/mac.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> index 9501def3e0e3e20132fdbcfe0b1f489694afdc5f..284f2eea71e5bf0a34c7fe84084d998164a31a05 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
> @@ -1681,8 +1681,7 @@ mt7996_msdu_page_get_from_cache(struct mt7996_dev *dev)
>  	if (!list_empty(&dev->wed_rro.page_cache)) {
>  		p = list_first_entry(&dev->wed_rro.page_cache,
>  				     struct mt7996_msdu_page, list);
> -		if (p)
> -			list_del(&p->list);
> +		list_del(&p->list);
>  	}
>  
>  	spin_unlock(&dev->wed_rro.lock);
> 
> ---
> base-commit: 211ddde0823f1442e4ad052a2f30f050145ccada
> change-id: 20251022-mt7996_mac_c-e10894b8bbb4
> 
> Best regards,
> -- 
> Rakuram Eswaran <rakuram.e96@...il.com>
> 

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