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

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Message-ID: <20161130094441.GB28680@localhost.localdomain>
Date:   Wed, 30 Nov 2016 10:44:41 +0100
From:   Richard Cochran <richardcochran@...il.com>
To:     Grygorii Strashko <grygorii.strashko@...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 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.

Thanks,
Richard