Date: Mon, 6 Oct 2014 15:22:15 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: linux-kernel@vger.kernel.org, Rusty Russell <rusty@rustcorp.com.au>,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org
Subject: Re: [PATCH 09/16] virtio-net: drop config_mutex
Message-ID: <20141006122215.GA26790@redhat.com>
References: <1412525038-15871-1-git-send-email-mst@redhat.com>
 <1412525038-15871-10-git-send-email-mst@redhat.com>
 <54328107.5090400@cogentembedded.com>
 <20141006115636.GA26184@redhat.com>
 <54328604.30403@cogentembedded.com>
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In-Reply-To: <54328604.30403@cogentembedded.com>
Sender: linux-kernel-owner@vger.kernel.org

On Mon, Oct 06, 2014 at 04:07:32PM +0400, Sergei Shtylyov wrote:
> On 10/6/2014 3:56 PM, Michael S. Tsirkin wrote:
> 
> >>>config_mutex served two purposes: prevent multiple concurrent config
> >>>change handlers, and synchronize access to config_enable flag.
> 
> >>>Since commit dbf2576e37da0fcc7aacbfbb9fd5d3de7888a3c1
> >>>     workqueue: make all workqueues non-reentrant
> >>>all workqueues are non-reentrant, and config_enable
> >>>is now gone.
> 
> >>>Get rid of the unnecessary lock.
> 
> >>>Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> >>>---
> >>>  drivers/net/virtio_net.c | 7 +------
> >>>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> >>>diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> >>>index fa17afa..d80fef4 100644
> >>>--- a/drivers/net/virtio_net.c
> >>>+++ b/drivers/net/virtio_net.c
> >>[...]
> >>>@@ -1430,7 +1426,7 @@ static void virtnet_config_changed_work(struct work_struct *work)
> >>>  		netif_tx_stop_all_queues(vi->dev);
> >>>  	}
> >>>  done:
> >>>-	mutex_unlock(&vi->config_lock);
> >>>+	return;
> 
> >>    There's no need for this *return*.
> 
> >I know - it's removed by the follow-up patch.
> 
>    Yeah, I saw.
> 
> >It's formatted like this to make diff smaller
> >and make review easier.
> 
>    Don't understand how adding this line makes diff smaller though...
> You first need to add it and then to delete it, where's the save?
> 
> WBR, Sergei


If I don't add it, gcc generates a compiler warning: it does not like
labels at the end of functions.
So I don't want to just drop the return function: I must drop the label too.


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