linux-kernel - Re: [PATCH v3] net: ksz884x: use time_before in netdev_open for compatibility and remove static variable

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Message-ID: <20220304214912.314b5829@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 4 Mar 2022 21:49:12 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     wudaemon <wudaemon@....com>
Cc:     davem@...emloft.net, m.grzeschik@...gutronix.de,
        chenhao288@...ilicon.com, arnd@...db.de, shenyang39@...wei.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] net: ksz884x: use time_before in netdev_open for
 compatibility and remove static variable

On Tue,  1 Mar 2022 15:18:08 +0000 wudaemon wrote:
> use time_before instead of direct compare for compatibility and remove the static next_jiffies variable
> 
> Signed-off-by: wudaemon <wudaemon@....com>

Oops, thought I replied to this one but apparently I haven't.
Sorry for the delay.

> diff --git a/drivers/net/ethernet/micrel/ksz884x.c b/drivers/net/ethernet/micrel/ksz884x.c
> index d024983815da..ce4f5c99c1ac 100644
> --- a/drivers/net/ethernet/micrel/ksz884x.c
> +++ b/drivers/net/ethernet/micrel/ksz884x.c
> @@ -5225,7 +5225,6 @@ static irqreturn_t netdev_intr(int irq, void *dev_id)
>   * Linux network device functions
>   */
>  
> -static unsigned long next_jiffies;
>  
>  #ifdef CONFIG_NET_POLL_CONTROLLER
>  static void netdev_netpoll(struct net_device *dev)
> @@ -5411,10 +5410,12 @@ static int netdev_open(struct net_device *dev)
>  	struct dev_info *hw_priv = priv->adapter;
>  	struct ksz_hw *hw = &hw_priv->hw;
>  	struct ksz_port *port = &priv->port;
> +	unsigned long next_jiffies;
>  	int i;
>  	int p;
>  	int rc = 0;
>  
> +	next_jiffies = jiffies;

This should probably be:

	next_jiffies = jiffies + HZ * 2;

and then...

>  	priv->multicast = 0;
>  	priv->promiscuous = 0;
>  
> @@ -5428,7 +5429,7 @@ static int netdev_open(struct net_device *dev)
>  		if (rc)
>  			return rc;
>  		for (i = 0; i < hw->mib_port_cnt; i++) {
> -			if (next_jiffies < jiffies)
> +			if (time_before(next_jiffies, jiffies))

I don't think this check is needed at all any more. Since we initialize
next_jiffies to jiffies earlier in the function it's got to be in the
right ballpark.

>  				next_jiffies = jiffies + HZ * 2;
>  			else
>  				next_jiffies += HZ * 1;

Remove the if and just leave this line to move the time forward.

Thanks!