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

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Date:   Thu, 12 Jan 2017 17:51:56 +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>,
        <igor.druzhinin@...rix.com>
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@...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;
-- 
1.8.3.1