netdev - RE: [PATCH] ks8851_ml ethernet network driver

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Date:	Thu, 17 Sep 2009 12:20:32 -0700
From:	"Choi, David" <David.Choi@...rel.Com>
To:	"Stephen Hemminger" <shemminger@...tta.com>,
	"Greg KH" <greg@...ah.com>, "Li, Charles" <Charles.Li@...rel.Com>
Cc:	<netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>,
	<Choi@...ah.com>, "Jeff Garzik" <jgarzik@...hat.com>
Subject: RE: [PATCH] ks8851_ml ethernet network driver

Hello Stephen Hemminger,

Here is my fix ups.
	-mutex_lock is intended to gurantee to access the hardware
registers 
	 exclusively. But as you mentioned, this mutex is redundancy in
ks_net_open() because this function does not access the hardware. So I
remove it.

================
@@ -858,7 +856,6 @@ static int ks_net_open(struct net_device
 	/* lock the card, even if we may not actually do anything
 	 * else at the moment.
 	 */
-	mutex_lock(&ks->lock);
 
 	if (netif_msg_ifup(ks))
 		ks_dbg(ks, "%s - entry\n", __func__);
@@ -875,8 +872,6 @@ static int ks_net_open(struct net_device
 	if (netif_msg_ifup(ks))
 		ks_dbg(ks, "network device %s up\n", netdev->name);
 
-	mutex_unlock(&ks->lock);
-
 	return 0;
 }


Regards,
David J. Choi


-----Original Message-----
From: Stephen Hemminger [mailto:shemminger@...tta.com] 
Sent: Wednesday, September 16, 2009 9:07 PM
To: Greg KH; Li, Charles
Cc: netdev@...r.kernel.org; David S. Miller; Choi@...ah.com; Choi,
David; Jeff Garzik
Subject: Re: [PATCH] ks8851_ml ethernet network driver

On Wed, 16 Sep 2009 19:38:36 -0700
Greg KH <greg@...ah.com> wrote:

> +
> +/**
> + * ks_net_open - open network device
> + * @netdev: The network device being opened.
> + *
> + * Called when the network device is marked active, such as a user
executing
> + * 'ifconfig up' on the device.
> + */
> +static int ks_net_open(struct net_device *netdev)
> +{
> +	struct ks_net *ks = netdev_priv(netdev);
> +	int err;
> +
> +#define	KS_INT_FLAGS	(IRQF_DISABLED|IRQF_TRIGGER_LOW)
> +	/* lock the card, even if we may not actually do anything
> +	 * else at the moment.
> +	 */
> +	mutex_lock(&ks->lock);
> +

I don't understand the purpose of ks->lock mutex. What is it
really protecting? open/close are already protected by rtnl_mutex,
is it really only for the PHY?
--
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