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

From: Leon Romanovsky <leon@kernel.org>
To: Ivan Vecera <ivecera@redhat.com>
Cc: netdev@vger.kernel.org, sassmann@redhat.com,
	Jacob Keller <jacob.e.keller@intel.com>,
	Patryk Piotrowski <patryk.piotrowski@intel.com>,
	SlawomirX Laba <slawomirx.laba@intel.com>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	"moderated list:INTEL ETHERNET DRIVERS" 
	<intel-wired-lan@lists.osuosl.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net] iavf: Do not restart Tx queues after reset task failure
Date: Wed, 9 Nov 2022 20:20:31 +0200	[thread overview]
Message-ID: <Y2vvbwkvAIOdtZaA@unreal> (raw)
In-Reply-To: <20221108102502.2147389-1-ivecera@redhat.com>

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
> 