linux-kernel - Re: [PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get

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Message-ID: <20260109090227.GA48150@wp.pl>
Date: Fri, 9 Jan 2026 10:02:27 +0100
From: Stanislaw Gruszka <stf_xl@...pl>
To: Tuo Li <islituo@...il.com>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE
 for il_sta in il3945_rs_get_rate()

Hi Tuo,

On Fri, Jan 09, 2026 at 11:40:14AM +0800, Tuo Li wrote:
> In this function, il_sta is not expected to be NULL. Add a defensive
> WARN_ON_ONCE() to catch this unexpected condition and aid debugging.
> 
> Signed-off-by: Tuo Li <islituo@...il.com>
> ---
> v3:
> * Replace plain NULL check with WARN_ON_ONCE() and update subject to better
>   reflect defensive nature of the check.
>   Thanks to Johannes Berg and Stanislaw Gruszka for helpful advice.
> v2:
> * Return early for uninitialized STA il data and align D_RATE messages with
>   il3945_rs_tx_status(). Add a wifi: prefix to the patch title.
>   Thanks to Stanislaw Gruszka for the helpful advice.
> ---
>  drivers/net/wireless/intel/iwlegacy/3945-rs.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/wireless/intel/iwlegacy/3945-rs.c b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> index 1826c37c090c..463565ce14af 100644
> --- a/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> +++ b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> @@ -626,6 +626,9 @@ il3945_rs_get_rate(void *il_r, struct ieee80211_sta *sta, void *il_sta,
>  
>  	D_RATE("enter\n");
>  
> +	if (WARN_ON_ONCE(!il_sta))
> +		return;
> +

Sorry for giving you wrong advice before, but after examining related code
I agree with Johannes the il_sta can not be NULL.
Now, I think we should just remove il_sta/rs_sta pointer check.

Regards
Stanislaw