[dpdk-dev] [PATCH v3] vhost: fix leak of fds and mmaps

[Rich Lane <rich.lane@bigswitch.com>]

The common vhost code only supported a single mmap per device. vhost-user
worked around this by saving the address/length/fd of each mmap after the end
of the rte_virtio_memory struct. This only works if the vhost-user code frees
dev->mem, since the common code is unaware of the extra info. The
VHOST_USER_RESET_OWNER message is one situation where the common code frees
dev->mem and leaks the fds and mappings. This happens every time I shut down a
VM.

The new code calls back into the implementation (vhost-user or vhost-cuse) to
clean up these resources.

The vhost-cuse changes are only compile tested.

Signed-off-by: Rich Lane <rlane@bigswitch.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
v2->v3:
- Rename "impl" to "backend".

v1->v2:
- Call into vhost-user/vhost-cuse to free mmaps.

 lib/librte_vhost/vhost-net.h                  |  6 ++++++
 lib/librte_vhost/vhost_cuse/virtio-net-cdev.c | 12 ++++++++++++
 lib/librte_vhost/vhost_user/vhost-net-user.c  |  1 -
 lib/librte_vhost/vhost_user/virtio-net-user.c | 25 ++++++++++---------------
 lib/librte_vhost/vhost_user/virtio-net-user.h |  1 -
 lib/librte_vhost/virtio-net.c                 |  8 +-------
 6 files changed, 29 insertions(+), 24 deletions(-)

diff --git a/lib/librte_vhost/vhost-net.h b/lib/librte_vhost/vhost-net.h
index c69b60b..affbd1a 100644
--- a/lib/librte_vhost/vhost-net.h
+++ b/lib/librte_vhost/vhost-net.h
@@ -115,4 +115,10 @@ struct vhost_net_device_ops {
 
 
 struct vhost_net_device_ops const *get_virtio_net_callbacks(void);
+
+/*
+ * Backend-specific cleanup. Defined by vhost-cuse and vhost-user.
+ */
+void vhost_backend_cleanup(struct virtio_net *dev);
+
 #endif /* _VHOST_NET_CDEV_H_ */
diff --git a/lib/librte_vhost/vhost_cuse/virtio-net-cdev.c b/lib/librte_vhost/vhost_cuse/virtio-net-cdev.c
index ae2c3fa..374c884 100644
--- a/lib/librte_vhost/vhost_cuse/virtio-net-cdev.c
+++ b/lib/librte_vhost/vhost_cuse/virtio-net-cdev.c
@@ -421,3 +421,15 @@ int cuse_set_backend(struct vhost_device_ctx ctx, struct vhost_vring_file *file)
 
 	return ops->set_backend(ctx, file);
 }
+
+void
+vhost_backend_cleanup(struct virtio_net *dev)
+{
+	/* Unmap QEMU memory file if mapped. */
+	if (dev->mem) {
+		munmap((void *)(uintptr_t)dev->mem->mapped_address,
+			(size_t)dev->mem->mapped_size);
+		free(dev->mem);
+		dev->mem = NULL;
+	}
+}
diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c b/lib/librte_vhost/vhost_user/vhost-net-user.c
index 8b7a448..336efba 100644
--- a/lib/librte_vhost/vhost_user/vhost-net-user.c
+++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
@@ -347,7 +347,6 @@ vserver_message_handler(int connfd, void *dat, int *remove)
 		close(connfd);
 		*remove = 1;
 		free(cfd_ctx);
-		user_destroy_device(ctx);
 		ops->destroy_device(ctx);
 
 		return;
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c b/lib/librte_vhost/vhost_user/virtio-net-user.c
index 2934d1c..993ed71 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.c
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
@@ -339,21 +339,6 @@ user_set_vring_enable(struct vhost_device_ctx ctx,
 }
 
 void
-user_destroy_device(struct vhost_device_ctx ctx)
-{
-	struct virtio_net *dev = get_device(ctx);
-
-	if (dev && (dev->flags & VIRTIO_DEV_RUNNING))
-		notify_ops->destroy_device(dev);
-
-	if (dev && dev->mem) {
-		free_mem_region(dev);
-		free(dev->mem);
-		dev->mem = NULL;
-	}
-}
-
-void
 user_set_protocol_features(struct vhost_device_ctx ctx,
 			   uint64_t protocol_features)
 {
@@ -365,3 +350,13 @@ user_set_protocol_features(struct vhost_device_ctx ctx,
 
 	dev->protocol_features = protocol_features;
 }
+
+void
+vhost_backend_cleanup(struct virtio_net *dev)
+{
+	if (dev->mem) {
+		free_mem_region(dev);
+		free(dev->mem);
+		dev->mem = NULL;
+	}
+}
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.h b/lib/librte_vhost/vhost_user/virtio-net-user.h
index b82108d..1140ee1 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.h
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.h
@@ -55,5 +55,4 @@ int user_get_vring_base(struct vhost_device_ctx, struct vhost_vring_state *);
 int user_set_vring_enable(struct vhost_device_ctx ctx,
 			  struct vhost_vring_state *state);
 
-void user_destroy_device(struct vhost_device_ctx);
 #endif
diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
index de78a0f..cf2560e 100644
--- a/lib/librte_vhost/virtio-net.c
+++ b/lib/librte_vhost/virtio-net.c
@@ -199,13 +199,7 @@ cleanup_device(struct virtio_net *dev, int destroy)
 {
 	uint32_t i;
 
-	/* Unmap QEMU memory file if mapped. */
-	if (dev->mem) {
-		munmap((void *)(uintptr_t)dev->mem->mapped_address,
-			(size_t)dev->mem->mapped_size);
-		free(dev->mem);
-		dev->mem = NULL;
-	}
+	vhost_backend_cleanup(dev);
 
 	for (i = 0; i < dev->virt_qp_nb; i++) {
 		cleanup_vq(dev->virtqueue[i * VIRTIO_QNUM + VIRTIO_RXQ], destroy);
-- 
1.9.1