linux-kernel - Re: [PATCH -next] net: stmmac: platform: remove useless if/else

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Message-ID: <20201029160137.5d8093a7@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date:   Thu, 29 Oct 2020 16:01:37 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Zou Wei <zou_wei@...wei.com>, peppe.cavallaro@...com,
        alexandre.torgue@...com, joabreu@...opsys.com, davem@...emloft.net,
        mcoquelin.stm32@...il.com, netdev@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] net: stmmac: platform: remove useless if/else

On Thu, 29 Oct 2020 13:34:45 +0100 Andrew Lunn wrote:
> On Thu, Oct 29, 2020 at 10:33:52AM +0800, Zou Wei wrote:
> > Fix the following coccinelle report:
> > 
> > ./drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c:233:6-8:
> > WARNING: possible condition with no effect (if == else)
> > 
> > Both branches are the same, so remove the else if/else altogether.
> > 
> > Reported-by: Hulk Robot <hulkci@...wei.com>
> > Signed-off-by: Zou Wei <zou_wei@...wei.com>
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > index af34a4c..f6c69d0 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> > @@ -230,8 +230,6 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
> >  		plat->tx_sched_algorithm = MTL_TX_ALGORITHM_WFQ;
> >  	else if (of_property_read_bool(tx_node, "snps,tx-sched-dwrr"))
> >  		plat->tx_sched_algorithm = MTL_TX_ALGORITHM_DWRR;
> > -	else if (of_property_read_bool(tx_node, "snps,tx-sched-sp"))
> > -		plat->tx_sched_algorithm = MTL_TX_ALGORITHM_SP;
> >  	else
> >  		plat->tx_sched_algorithm = MTL_TX_ALGORITHM_SP;  
> 
> I actually prefer the original code. Code is also documentation. It
> documents the fact, if "snps,tx-sched-sp" is in device tree, we use
> MTL_TX_ALGORITHM_SP, but otherwise we default to MTL_TX_ALGORITHM_SP.
> 
> As with my suggestion for forcedeth, i would move the default setting
> to before the whole if/else if/else block to document it is the
> default.
> 
> Or just consider this a false positive and leave it alone. I can see
> value in the coccinelle script, but it is going to have a lot of false
> positive cases, so i'm not sure there is value in working around them
> all.

Annoyingly this is not the first time this exact patch is submitted :/

I think your forcedeth suggestion is a nice compromise.