netdev - Re: [PATCH net-next 2/2] net: stmmac: Use helper function IS_ERR_OR

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Message-ID: <ZN3xTiaIGPzfmEjY@shell.armlinux.org.uk>
Date: Thu, 17 Aug 2023 11:07:10 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Ruan Jinjie <ruanjinjie@...wei.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, lars.povlsen@...rochip.com,
	Steen.Hegelund@...rochip.com, daniel.machon@...rochip.com,
	alexandre.torgue@...s.st.com, joabreu@...opsys.com,
	mcoquelin.stm32@...il.com, horatiu.vultur@...rochip.com,
	simon.horman@...igine.com, netdev@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH net-next 2/2] net: stmmac: Use helper function
 IS_ERR_OR_NULL()

On Thu, Aug 17, 2023 at 03:19:41PM +0800, Ruan Jinjie wrote:
> Use IS_ERR_OR_NULL() instead of open-coding it
> to simplify the code.
> 
> Signed-off-by: Ruan Jinjie <ruanjinjie@...wei.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 733b5e900817..fe2452a70d23 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1165,7 +1165,7 @@ static int stmmac_init_phy(struct net_device *dev)
>  	/* Some DT bindings do not set-up the PHY handle. Let's try to
>  	 * manually parse it
>  	 */
> -	if (!phy_fwnode || IS_ERR(phy_fwnode)) {
> +	if (IS_ERR_OR_NULL(phy_fwnode)) {
>  		int addr = priv->plat->phy_addr;
>  		struct phy_device *phydev;

Up to the stmmac maintainers, but I have never been a fan of
"IS_ERR_OR_NULL" because it leads to programming errors such as
those I pointed out in your changes to I2C drivers. I would
much rather see IS_ERR_OR_NULL removed from the kernel entirely.
That is my personal opinion.

In this case, it doesn't matter because we're not returning the
phy_fwnode error, we're detecting it and taking some alternative
action - but given my inherent dislike of IS_ERR_OR_NULL, I
prefer the original.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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