netdev - Re: [PATCH net-next v2 2/2] net: qed_dev: fix redundant check of rc and against -EINVAL

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Message-ID: <20211022144720.7d1d9eb6@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 22 Oct 2021 14:47:20 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Jεan Sacren <sakiwit@...il.com>
Cc:     Ariel Elior <aelior@...vell.com>, GR-everest-linux-l2@...vell.com,
        davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 2/2] net: qed_dev: fix redundant check of rc
 and against -EINVAL

On Thu, 21 Oct 2021 21:37:41 -0600 Jεan Sacren wrote:
> From: Jean Sacren <sakiwit@...il.com>
> 
> We should first check rc alone and then check it against -EINVAL to
> avoid repeating the same operation multiple times.
> 
> We should also remove the check of !rc in this expression since it is
> always true:
> 
> 	(!rc && !resc_lock_params.b_granted)
> 
> Signed-off-by: Jean Sacren <sakiwit@...il.com>

The code seems to be written like this on purpose. You're adding
indentation levels, and making the structure less readable IMO.

If you want to avoid checking rc / !rc multiple times you can just
code it as:

	if (rc == -EINVAL)
		...
	else if (rc)
		...
	else if (!granted)
		...
	else
		...

I'm not sure I see the point of the re-factoring.

> (1) Fix missing else branch. I'm very sorry.
> (2) Add text for !rc removal in the changelog.
> (3) Put two lines of qed_mcp_resc_unlock() call into one.
>     Thank you, Mr. Horman!
>  drivers/net/ethernet/qlogic/qed/qed_dev.c | 31 +++++++++++++----------
>  1 file changed, 17 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/net/ethernet/qlogic/qed/qed_dev.c b/drivers/net/ethernet/qlogic/qed/qed_dev.c
> index 18f3bf7c4dfe..4ae9867b2535 100644
> --- a/drivers/net/ethernet/qlogic/qed/qed_dev.c
> +++ b/drivers/net/ethernet/qlogic/qed/qed_dev.c
> @@ -3987,26 +3987,29 @@ static int qed_hw_get_resc(struct qed_hwfn *p_hwfn, struct qed_ptt *p_ptt)
>  				       QED_RESC_LOCK_RESC_ALLOC, false);
>  
>  	rc = qed_mcp_resc_lock(p_hwfn, p_ptt, &resc_lock_params);
> -	if (rc && rc != -EINVAL) {
> -		return rc;
> -	} else if (rc == -EINVAL) {
> +	if (rc) {
> +		if (rc != -EINVAL)
> +			return rc;
>  		DP_INFO(p_hwfn,
>  			"Skip the max values setting of the soft resources since the resource lock is not supported by the MFW\n");
> -	} else if (!rc && !resc_lock_params.b_granted) {
> -		DP_NOTICE(p_hwfn,
> -			  "Failed to acquire the resource lock for the resource allocation commands\n");
> -		return -EBUSY;
>  	} else {
> -		rc = qed_hw_set_soft_resc_size(p_hwfn, p_ptt);
> -		if (rc && rc != -EINVAL) {
> +		if (!resc_lock_params.b_granted) {
>  			DP_NOTICE(p_hwfn,
> -				  "Failed to set the max values of the soft resources\n");
> -			goto unlock_and_exit;
> -		} else if (rc == -EINVAL) {
> +				  "Failed to acquire the resource lock for the resource allocation commands\n");
> +			return -EBUSY;
> +		}
> +
> +		rc = qed_hw_set_soft_resc_size(p_hwfn, p_ptt);
> +		if (rc) {
> +			if (rc != -EINVAL) {
> +				DP_NOTICE(p_hwfn,
> +					  "Failed to set the max values of the soft resources\n");
> +				goto unlock_and_exit;
> +			}
> +
>  			DP_INFO(p_hwfn,
>  				"Skip the max values setting of the soft resources since it is not supported by the MFW\n");
> -			rc = qed_mcp_resc_unlock(p_hwfn, p_ptt,
> -						 &resc_unlock_params);
> +			rc = qed_mcp_resc_unlock(p_hwfn, p_ptt, &resc_unlock_params);
>  			if (rc)
>  				DP_INFO(p_hwfn,
>  					"Failed to release the resource lock for the resource allocation commands\n");