Re: [PATCH] wifi: iwlegacy: 3945: protect sysfs TX power update with mutex

[Stanislaw Gruszka]

On Tue, Sep 29, 2026 at 08:33:29PM +0800, Runyu Xiao wrote:
> The sysfs tx_power store handler calls il3945_hw_reg_set_txpower(), whose
> command path requires il->mutex to be held. The callback bypasses the mutex
> used by the other 3945 control paths, triggering the lockdep assertion and
> allowing concurrent TX power updates to race with other command or state
> transitions. Serialize the update with the same mutex.
> 
> Fixes: b481de9ca074 ("[IWLWIFI]: add iwlwifi wireless drivers")
> Cc: stable@xxxxxxxxxxxxxxx
> Assisted-by: LLM
> Signed-off-by: Runyu Xiao <runyu.xiao@xxxxxxxxxx>
Acked-by: Stanislaw Gruszka <stf_xl@xxxxx>

> ---
>  drivers/net/wireless/intel/iwlegacy/3945-mac.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlegacy/3945-mac.c b/drivers/net/wireless/intel/iwlegacy/3945-mac.c
> index cbaf25062..e8cbc2993 100644
> --- a/drivers/net/wireless/intel/iwlegacy/3945-mac.c
> +++ b/drivers/net/wireless/intel/iwlegacy/3945-mac.c
> @@ -3083,10 +3083,13 @@ il3945_store_tx_power(struct device *d, struct device_attribute *attr,
>  	u32 val;
>  
>  	val = simple_strtoul(p, &p, 10);
> -	if (p == buf)
> +	if (p == buf) {
>  		IL_INFO(": %s is not in decimal form.\n", buf);
> -	else
> +	} else {
> +		mutex_lock(&il->mutex);
>  		il3945_hw_reg_set_txpower(il, val);
> +		mutex_unlock(&il->mutex);
> +	}
>  
>  	return count;
>  }
> -- 
> 2.34.1