netdev - Re: [PATCH 1/6] net: ethernet: ti: netcp: add support of cpts

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Date:   Wed, 30 Nov 2016 11:31:56 -0600
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Richard Cochran <richardcochran@...il.com>
CC:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Mugunthan V N <mugunthanvnm@...com>,
        Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
        <devicetree@...r.kernel.org>,
        Murali Karicheri <m-karicheri2@...com>,
        Wingman Kwok <w-kwok2@...com>
Subject: Re: [PATCH 1/6] net: ethernet: ti: netcp: add support of cpts



On 11/30/2016 03:44 AM, Richard Cochran wrote:
> On Mon, Nov 28, 2016 at 05:04:23PM -0600, Grygorii Strashko wrote:
>> @@ -678,6 +744,9 @@ struct gbe_priv {
>>  	int				num_et_stats;
>>  	/*  Lock for updating the hwstats */
>>  	spinlock_t			hw_stats_lock;
>> +
>> +	int                             cpts_registered;
> 
> The usage of this counter is racy.
> 
>> +	struct cpts                     *cpts;
>>  };
> 
> This ++ and -- business ...
> 
>> +static void gbe_register_cpts(struct gbe_priv *gbe_dev)
>> +{
>> +	if (!gbe_dev->cpts)
>> +		return;
>> +
>> +	if (gbe_dev->cpts_registered > 0)
>> +		goto done;
>> +
>> +	if (cpts_register(gbe_dev->cpts)) {
>> +		dev_err(gbe_dev->dev, "error registering cpts device\n");
>> +		return;
>> +	}
>> +
>> +done:
>> +	++gbe_dev->cpts_registered;
>> +}
>> +
>> +static void gbe_unregister_cpts(struct gbe_priv *gbe_dev)
>> +{
>> +	if (!gbe_dev->cpts || (gbe_dev->cpts_registered <= 0))
>> +		return;
>> +
>> +	if (--gbe_dev->cpts_registered)
>> +		return;
>> +
>> +	cpts_unregister(gbe_dev->cpts);
>> +}
> 
> is invoked from your open() and close() methods, but those methods
> are not serialized among multiple ports.
> 

ok. Seems my assumption that ndo_open/ndo_close serialized by rtnl_lock is incorrect. Right?
net_device_ops.ndo_open ->
 netcp_ndo_open
 gbe_open
 gbe_register_cpts

-- 
regards,
-grygorii