netdev - Re: [PATCH] xen-netback: fix memory leaks on XenBus disconnect

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Message-ID: <ac2136fd-a1c7-d990-a79b-ec5e24daa543@citrix.com>
Date:   Thu, 12 Jan 2017 18:05:36 +0000
From:   Igor Druzhinin <igor.druzhinin@...rix.com>
To:     <wei.liu2@...rix.com>, <xen-devel@...ts.xenproject.org>,
        <paul.durrant@...rix.com>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <jgross@...e.com>
Subject: Re: [PATCH] xen-netback: fix memory leaks on XenBus disconnect

On 12/01/17 17:51, Igor Druzhinin wrote:
> Eliminate memory leaks introduced several years ago by cleaning the queue
> resources which are allocated on XenBus connection event. Namely, queue
> structure array and pages used for IO rings.
> vif->lock is used to protect statistics gathering agents from using the
> queue structure during cleaning.
> 
> Signed-off-by: Igor Druzhinin <igor.druzhinin@...rix.com>
> ---
>  drivers/net/xen-netback/interface.c |  6 ++++--
>  drivers/net/xen-netback/xenbus.c    | 13 +++++++++++++
>  2 files changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index e30ffd2..5795213 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -221,18 +221,18 @@ static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
>  {
>  	struct xenvif *vif = netdev_priv(dev);
>  	struct xenvif_queue *queue = NULL;
> -	unsigned int num_queues = vif->num_queues;
>  	unsigned long rx_bytes = 0;
>  	unsigned long rx_packets = 0;
>  	unsigned long tx_bytes = 0;
>  	unsigned long tx_packets = 0;
>  	unsigned int index;
>  
> +	spin_lock(&vif->lock);
>  	if (vif->queues == NULL)
>  		goto out;
>  
>  	/* Aggregate tx and rx stats from each queue */
> -	for (index = 0; index < num_queues; ++index) {
> +	for (index = 0; index < vif->num_queues; ++index) {
>  		queue = &vif->queues[index];
>  		rx_bytes += queue->stats.rx_bytes;
>  		rx_packets += queue->stats.rx_packets;
> @@ -241,6 +241,8 @@ static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
>  	}
>  
>  out:
> +	spin_unlock(&vif->lock);
> +
>  	vif->dev->stats.rx_bytes = rx_bytes;
>  	vif->dev->stats.rx_packets = rx_packets;
>  	vif->dev->stats.tx_bytes = tx_bytes;
> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
> index 3124eae..85b742e 100644
> --- a/drivers/net/xen-netback/xenbus.c
> +++ b/drivers/net/xen-netback/xenbus.c
> @@ -493,11 +493,22 @@ static int backend_create_xenvif(struct backend_info *be)
>  static void backend_disconnect(struct backend_info *be)
>  {
>  	if (be->vif) {
> +		unsigned int queue_index;
> +
>  		xen_unregister_watchers(be->vif);
>  #ifdef CONFIG_DEBUG_FS
>  		xenvif_debugfs_delif(be->vif);
>  #endif /* CONFIG_DEBUG_FS */
>  		xenvif_disconnect_data(be->vif);
> +		for (queue_index = 0; queue_index < be->vif->num_queues; ++queue_index)
> +			xenvif_deinit_queue(&be->vif->queues[queue_index]);
> +
> +		spin_lock(&be->vif->lock);
> +		vfree(be->vif->queues);
> +		be->vif->num_queues = 0;
> +		be->vif->queues = NULL;
> +		spin_unlock(&be->vif->lock);
> +
>  		xenvif_disconnect_ctrl(be->vif);
>  	}
>  }
> @@ -1034,6 +1045,8 @@ static void connect(struct backend_info *be)
>  err:
>  	if (be->vif->num_queues > 0)
>  		xenvif_disconnect_data(be->vif); /* Clean up existing queues */
> +	for (queue_index = 0; queue_index < be->vif->num_queues; ++queue_index)
> +		xenvif_deinit_queue(&be->vif->queues[queue_index]);
>  	vfree(be->vif->queues);
>  	be->vif->queues = NULL;
>  	be->vif->num_queues = 0;
> 

Add Juergen Gross to CC.

Igor