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From: Stefano Garzarella <sgarzare@redhat.com>
To: netdev@vger.kernel.org
Cc: linux-hyperv@vger.kernel.org,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	virtualization@lists.linux-foundation.org,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Jason Wang <jasowang@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Dexuan Cui <decui@microsoft.com>,
	Jorgen Hansen <jhansen@vmware.com>
Subject: [RFC PATCH 12/13] vsock: prevent transport modules unloading
Date: Fri, 27 Sep 2019 13:27:02 +0200
Message-ID: <20190927112703.17745-13-sgarzare@redhat.com> (raw)
In-Reply-To: <20190927112703.17745-1-sgarzare@redhat.com>

This patch adds 'module' member in the 'struct vsock_transport'
in order to get/put the transport module. This prevents the
module unloading while sockets are assigned to it.

We increase the module refcnt when a socket is assigned to a
transport, and we decrease the module refcnt when the socket
is destructed.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 drivers/vhost/vsock.c            |  1 +
 include/net/af_vsock.h           |  1 +
 net/vmw_vsock/af_vsock.c         | 23 +++++++++++++++++------
 net/vmw_vsock/hyperv_transport.c |  1 +
 net/vmw_vsock/virtio_transport.c |  1 +
 net/vmw_vsock/vmci_transport.c   |  1 +
 6 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 375af01a5b64..6d7a8fc9eb63 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -387,6 +387,7 @@ static bool vhost_vsock_more_replies(struct vhost_vsock *vsock)
 static struct virtio_transport vhost_transport = {
 	.transport = {
 		.features                 = VSOCK_TRANSPORT_F_H2G,
+		.module                   = THIS_MODULE,
 
 		.get_local_cid            = vhost_transport_get_local_cid,
 
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index 2a081d19e20d..f10fa918bf23 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -100,6 +100,7 @@ struct vsock_transport_send_notify_data {
 
 struct vsock_transport {
 	uint64_t features;
+	struct module *module;
 
 	/* Initialize/tear-down socket. */
 	int (*init)(struct vsock_sock *, struct vsock_sock *);
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index c5f46b8242ce..750b62711b01 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -416,13 +416,28 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
 		return -ESOCKTNOSUPPORT;
 	}
 
-	if (!vsk->transport)
+	/* We increase the module refcnt to prevent the tranport unloading
+	 * while there are open sockets assigned to it.
+	 */
+	if (!vsk->transport || !try_module_get(vsk->transport->module)) {
+		vsk->transport = NULL;
 		return -ENODEV;
+	}
 
 	return vsk->transport->init(vsk, psk);
 }
 EXPORT_SYMBOL_GPL(vsock_assign_transport);
 
+static void vsock_deassign_transport(struct vsock_sock *vsk)
+{
+	if (!vsk->transport)
+		return;
+
+	vsk->transport->destruct(vsk);
+	module_put(vsk->transport->module);
+	vsk->transport = NULL;
+}
+
 static bool vsock_find_cid(unsigned int cid)
 {
 	if (transport_g2h && cid == transport_g2h->get_local_cid())
@@ -728,8 +743,7 @@ static void vsock_sk_destruct(struct sock *sk)
 {
 	struct vsock_sock *vsk = vsock_sk(sk);
 
-	if (vsk->transport)
-		vsk->transport->destruct(vsk);
+	vsock_deassign_transport(vsk);
 
 	/* When clearing these addresses, there's no need to set the family and
 	 * possibly register the address family with the kernel.
@@ -2161,9 +2175,6 @@ void vsock_core_unregister(const struct vsock_transport *t)
 {
 	mutex_lock(&vsock_register_mutex);
 
-	/* RFC-TODO: maybe we should check if there are open sockets
-	 * assigned to that transport and avoid the unregistration
-	 */
 	if (transport_h2g == t)
 		transport_h2g = NULL;
 
diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index 94e6fc905a77..bd4f3c222904 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -857,6 +857,7 @@ int hvs_notify_send_post_enqueue(struct vsock_sock *vsk, ssize_t written,
 
 static struct vsock_transport hvs_transport = {
 	.features                 = VSOCK_TRANSPORT_F_G2H,
+	.module                   = THIS_MODULE,
 
 	.get_local_cid            = hvs_get_local_cid,
 
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 0ff037ef7f8e..439fe01e6691 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -463,6 +463,7 @@ static void virtio_vsock_rx_done(struct virtqueue *vq)
 static struct virtio_transport virtio_transport = {
 	.transport = {
 		.features                 = VSOCK_TRANSPORT_F_G2H,
+		.module                   = THIS_MODULE,
 
 		.get_local_cid            = virtio_transport_get_local_cid,
 
diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c
index 52e63952d0d4..900392686c03 100644
--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -2021,6 +2021,7 @@ static u32 vmci_transport_get_local_cid(void)
 
 static struct vsock_transport vmci_transport = {
 	.features = VSOCK_TRANSPORT_F_DGRAM | VSOCK_TRANSPORT_F_H2G,
+	.module = THIS_MODULE,
 	.init = vmci_transport_socket_init,
 	.destruct = vmci_transport_destruct,
 	.release = vmci_transport_release,
-- 
2.21.0


  parent reply index

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-27 11:26 [RFC PATCH 00/13] vsock: add multi-transports support Stefano Garzarella
2019-09-27 11:26 ` [RFC PATCH 01/13] vsock/vmci: remove unused VSOCK_DEFAULT_CONNECT_TIMEOUT Stefano Garzarella
2019-10-09 11:41   ` Stefan Hajnoczi
2019-09-27 11:26 ` [RFC PATCH 02/13] vsock: remove vm_sockets_get_local_cid() Stefano Garzarella
2019-10-09 11:42   ` Stefan Hajnoczi
2019-09-27 11:26 ` [RFC PATCH 03/13] vsock: remove include/linux/vm_sockets.h file Stefano Garzarella
2019-10-09 11:43   ` Stefan Hajnoczi
2019-09-27 11:26 ` [RFC PATCH 04/13] vsock: add 'transport' member in the struct vsock_sock Stefano Garzarella
2019-10-09 11:46   ` Stefan Hajnoczi
2019-09-27 11:26 ` [RFC PATCH 05/13] vsock/virtio: add transport parameter to the virtio_transport_reset_no_sock() Stefano Garzarella
2019-10-09 11:52   ` Stefan Hajnoczi
2019-09-27 11:26 ` [RFC PATCH 06/13] vsock: add 'struct vsock_sock *' param to vsock_core_get_transport() Stefano Garzarella
2019-10-09 11:54   ` Stefan Hajnoczi
2019-10-10  8:50     ` Stefano Garzarella
2019-09-27 11:26 ` [RFC PATCH 07/13] vsock: handle buffer_size sockopts in the core Stefano Garzarella
2019-10-03 20:11   ` Dexuan Cui
2019-10-09 12:30   ` Stefan Hajnoczi
2019-10-10  9:32     ` Stefano Garzarella
2019-10-11  8:27       ` Stefan Hajnoczi
2019-10-11  8:51         ` Stefano Garzarella
2019-09-27 11:26 ` [RFC PATCH 08/13] vsock: move vsock_insert_unbound() in the vsock_create() Stefano Garzarella
2019-10-03 20:17   ` Dexuan Cui
2019-10-09 12:34   ` Stefan Hajnoczi
2019-10-10  9:52     ` Stefano Garzarella
2019-09-27 11:26 ` [RFC PATCH 09/13] hv_sock: set VMADDR_CID_HOST in the hvs_remote_addr_init() Stefano Garzarella
2019-10-03 19:36   ` Dexuan Cui
2019-10-09 12:35   ` Stefan Hajnoczi
2019-09-27 11:27 ` [RFC PATCH 10/13] vsock: add multi-transports support Stefano Garzarella
2019-10-09 13:11   ` Stefan Hajnoczi
2019-10-10 12:55     ` Stefano Garzarella
2019-09-27 11:27 ` [RFC PATCH 11/13] vsock: add 'transport_hg' to handle g2h\h2g transports Stefano Garzarella
2019-10-09  9:44   ` Stefano Garzarella
2019-10-09 13:16   ` Stefan Hajnoczi
2019-10-10 13:04     ` Stefano Garzarella
2019-09-27 11:27 ` Stefano Garzarella [this message]
2019-10-09 13:28   ` [RFC PATCH 12/13] vsock: prevent transport modules unloading Stefan Hajnoczi
2019-09-27 11:27 ` [RFC PATCH 13/13] vsock: fix bind() behaviour taking care of CID Stefano Garzarella
2019-10-09 13:29   ` Stefan Hajnoczi
2019-10-04  0:04 ` [RFC PATCH 00/13] vsock: add multi-transports support Dexuan Cui
2019-10-04  9:16   ` Stefano Garzarella
2019-10-09 13:29 ` Stefan Hajnoczi
2019-10-10  8:45   ` Stefano Garzarella

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