netdev - Re: [PATCH net] bnxt_en: Fix potential race condition in bnxt_tx

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Message-Id: <20160715.232048.1780795244111833927.davem@davemloft.net>
Date:	Fri, 15 Jul 2016 23:20:48 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	f.fainelli@...il.com
Cc:	netdev@...r.kernel.org, michael.chan@...adcom.com,
	huangjw@...adcom.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] bnxt_en: Fix potential race condition in
 bnxt_tx_enable()

From: Florian Fainelli <f.fainelli@...il.com>
Date: Fri, 15 Jul 2016 16:42:01 -0700

> @@ -4599,7 +4599,9 @@ static void bnxt_tx_enable(struct bnxt *bp)
>  	for (i = 0; i < bp->tx_nr_rings; i++) {
>  		txr = &bp->tx_ring[i];
>  		txq = netdev_get_tx_queue(bp->dev, i);
> +		__netif_tx_lock(txq, smp_processor_id());
>  		txr->dev_state = 0;
> +		__netif_tx_unlock(txq);

You're going to have to explain how this could possibly cause a
problem, because I'm pretty sure it can't.

Either the reader sees 0, or non-zero, in this value.

And adding locking around this assignment does not change that at all.