linux-kernel - Re: [PATCH wireless] wifi: ath10k: Fix an error code problem in ath10k_dbg_sta_write_peer_debug

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Date: Fri, 19 Apr 2024 08:09:24 -0700
From: Jeff Johnson <quic_jjohnson@...cinc.com>
To: Su Hui <suhui@...china.com>, <kvalo@...nel.org>, <jjohnson@...nel.org>,
        <nathan@...nel.org>, <ndesaulniers@...gle.com>, <morbo@...gle.com>,
        <justinstitt@...gle.com>
CC: <c_mkenna@....qualcomm.com>, <linux-wireless@...r.kernel.org>,
        <ath10k@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <llvm@...ts.linux.dev>, <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH wireless] wifi: ath10k: Fix an error code problem in
 ath10k_dbg_sta_write_peer_debug_trigger()

On 4/17/2024 1:17 AM, Su Hui wrote:
> Clang Static Checker (scan-build) Warning:
> drivers/net/wireless/ath/ath10k/debugfs_sta.c:line 429, column 3
> Value stored to 'ret' is never read.
> 
> Return 'ret' rather than 'count' when 'ret' stores an error code.
> By the way, remove some useless code.
> 
> Fixes: ee8b08a1be82 ("ath10k: add debugfs support to get per peer tids log via tracing")
> Signed-off-by: Su Hui <suhui@...china.com>
> ---
>  drivers/net/wireless/ath/ath10k/debugfs_sta.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath10k/debugfs_sta.c b/drivers/net/wireless/ath/ath10k/debugfs_sta.c
> index 394bf3c32abf..5525dabe390a 100644
> --- a/drivers/net/wireless/ath/ath10k/debugfs_sta.c
> +++ b/drivers/net/wireless/ath/ath10k/debugfs_sta.c
> @@ -415,7 +415,7 @@ ath10k_dbg_sta_write_peer_debug_trigger(struct file *file,
>  	struct ath10k_sta *arsta = (struct ath10k_sta *)sta->drv_priv;
>  	struct ath10k *ar = arsta->arvif->ar;
>  	u8 peer_debug_trigger;
> -	int ret;
> +	int ret = 0;

this is unnecessary since this will be written in all paths that lead to the
return that reads it

>  
>  	if (kstrtou8_from_user(user_buf, count, 0, &peer_debug_trigger))
>  		return -EINVAL;
> @@ -432,14 +432,12 @@ ath10k_dbg_sta_write_peer_debug_trigger(struct file *file,
>  
>  	ret = ath10k_wmi_peer_set_param(ar, arsta->arvif->vdev_id, sta->addr,
>  					ar->wmi.peer_param->debug, peer_debug_trigger);
> -	if (ret) {
> +	if (ret)
>  		ath10k_warn(ar, "failed to set param to trigger peer tid logs for station ret: %d\n",
>  			    ret);
> -		goto out;
> -	}
>  out:
>  	mutex_unlock(&ar->conf_mutex);
> -	return count;
> +	return ret ?: count;
>  }
>  
>  static const struct file_operations fops_peer_debug_trigger = {

I'd suggest as an alternate solution that this function is a good candidate
for the the cleanup.h functionality. By scoping the mutex_lock() you can
simply return at each error location, and remove the explicit mutex_unlock().

But I'd accept this with the initializer change removed as well since I don't
think ath10k has any cleanup.h usages yet.

/jeff