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

From: Paul Durrant
Date: Fri Jan 13 2017 - 04:01:48 EST


> -----Original Message-----
> From: Igor Druzhinin [mailto:igor.druzhinin@xxxxxxxxxx]
> Sent: 12 January 2017 17:52
> To: Wei Liu <wei.liu2@xxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx; Paul
> Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Igor Druzhinin
> <igor.druzhinin@xxxxxxxxxx>
> Subject: [PATCH] xen-netback: fix memory leaks on XenBus disconnect
>
> 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@xxxxxxxxxx>

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

...although I was involved with discussions concerning this, so Wei should probably look it over too.

> ---
> 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;
> --
> 1.8.3.1