linux-kernel - Re: [PATCH net] iavf: Do not restart Tx queues after reset task failure

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Date:   Wed, 9 Nov 2022 20:20:31 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Ivan Vecera <ivecera@...hat.com>
Cc:     netdev@...r.kernel.org, sassmann@...hat.com,
        Jacob Keller <jacob.e.keller@...el.com>,
        Patryk Piotrowski <patryk.piotrowski@...el.com>,
        SlawomirX Laba <slawomirx.laba@...el.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "moderated list:INTEL ETHERNET DRIVERS" 
        <intel-wired-lan@...ts.osuosl.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] iavf: Do not restart Tx queues after reset task
 failure

On Tue, Nov 08, 2022 at 11:25:02AM +0100, Ivan Vecera wrote:
> After commit aa626da947e9 ("iavf: Detach device during reset task")
> the device is detached during reset task and re-attached at its end.
> The problem occurs when reset task fails because Tx queues are
> restarted during device re-attach and this leads later to a crash.

<...>

> +	if (netif_running(netdev)) {
> +		/* Close device to ensure that Tx queues will not be started
> +		 * during netif_device_attach() at the end of the reset task.
> +		 */
> +		rtnl_lock();
> +		dev_close(netdev);
> +		rtnl_unlock();
> +	}

Sorry for my naive question, I see this pattern a lot (including RDMA), 
so curious. Everyone checks netif_running() outside of rtnl_lock, while
dev_close() changes state bit __LINK_STATE_START. Shouldn't rtnl_lock()
placed before netif_running()?

Thanks

> +
>  	dev_err(&adapter->pdev->dev, "failed to allocate resources during reinit\n");
>  reset_finish:
>  	rtnl_lock();
> -- 
> 2.37.4
>