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Subject[PATCH v21 096/100] c/r: Add checkpoint support for veth devices (v2)
Date
From: Dan Smith <danms@us.ibm.com>

Adds an ndo_checkpoint() handler for veth devices to checkpoint themselves.
Writes out the pairing information, addresses, and initiates a checkpoint
on the peer if the peer won't be reached from another netns. Throws an
error of our peer's netns isn't already in the hash (i.e., a tree leak).

Changelog[v21]
- Unbreak compiling with CONFIG_CHECKPOINT=n or CONFIG_NET_NS=n
- Clean up the error path in restore_veth()

Changes in v2:
- Fix check detecting if peer is in the init netns

Cc: netdev@vger.kernel.org
Signed-off-by: Dan Smith <danms@us.ibm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Oren Laadan <orenl@cs.columbia.edu>
---
drivers/net/veth.c | 76 +++++++++++++++++++++++++++++++++++++++++++
net/checkpoint_dev.c | 87 +++++++++++++++++--------------------------------
2 files changed, 106 insertions(+), 57 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index f9f0730..d76b5e0 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -285,6 +285,79 @@ static void veth_dev_free(struct net_device *dev)
free_netdev(dev);
}

+#ifdef CONFIG_NETNS_CHECKPOINT
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+
+static int veth_checkpoint(struct ckpt_ctx *ctx, struct net_device *dev)
+{
+ struct ckpt_hdr_netdev *h;
+ struct veth_priv *priv = netdev_priv(dev);
+ struct net_device *peer = priv->peer;
+ struct ckpt_netdev_addr *addrs;
+ int ret;
+ int n;
+
+ if (!peer) {
+ ckpt_err(ctx, -EINVAL, "veth device has no peer!\n");
+ return -EINVAL;
+ }
+
+ h = ckpt_netdev_base(ctx, dev, &addrs);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ h->type = CKPT_NETDEV_VETH;
+
+ ret = h->veth.this_ref = ckpt_obj_lookup_add(ctx, dev,
+ CKPT_OBJ_NETDEV, &n);
+ if (ret < 0)
+ goto out;
+
+ ret = h->veth.peer_ref = ckpt_obj_lookup_add(ctx, peer,
+ CKPT_OBJ_NETDEV, &n);
+ if (ret < 0)
+ goto out;
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *)h);
+ if (ret < 0)
+ goto out;
+
+ ret = ckpt_write_buffer(ctx, dev->name, IFNAMSIZ);
+ if (ret < 0)
+ goto out;
+
+ ret = ckpt_write_buffer(ctx, peer->name, IFNAMSIZ);
+ if (ret < 0)
+ goto out;
+
+ if (h->inet_addrs > 0) {
+ int len = (sizeof(struct ckpt_netdev_addr) * h->inet_addrs);
+ ret = ckpt_write_buffer(ctx, addrs, len);
+ if (ret)
+ goto out;
+ }
+
+ /* Only checkpoint peer if we're not going to arrive at it
+ * via another task's netns. Fail if the pipe exits
+ * our container to a netns not already in the hash
+ */
+ if (ckpt_netdev_in_init_netns(ctx, peer))
+ ret = checkpoint_obj(ctx, peer, CKPT_OBJ_NETDEV);
+ else if (!ckpt_obj_lookup(ctx, peer->nd_net, CKPT_OBJ_NET_NS)) {
+ ret = -EINVAL;
+ ckpt_err(ctx, ret,
+ "Peer %s of %s not in checkpointed namespaces\n",
+ peer->name, dev->name);
+ }
+ out:
+ ckpt_hdr_put(ctx, h);
+ kfree(addrs);
+
+ return ret;
+}
+#endif
+
static const struct net_device_ops veth_netdev_ops = {
.ndo_init = veth_dev_init,
.ndo_open = veth_open,
@@ -293,6 +366,9 @@ static const struct net_device_ops veth_netdev_ops = {
.ndo_change_mtu = veth_change_mtu,
.ndo_get_stats = veth_get_stats,
.ndo_set_mac_address = eth_mac_addr,
+#ifdef CONFIG_NETNS_CHECKPOINT
+ .ndo_checkpoint = veth_checkpoint,
+#endif
};

static void veth_setup(struct net_device *dev)
diff --git a/net/checkpoint_dev.c b/net/checkpoint_dev.c
index 5097011..a8e3341 100644
--- a/net/checkpoint_dev.c
+++ b/net/checkpoint_dev.c
@@ -20,11 +20,6 @@
#include <net/net_namespace.h>
#include <net/sch_generic.h>

-struct dq_netdev {
- struct net_device *dev;
- struct ckpt_ctx *ctx;
-};
-
struct veth_newlink {
char *peer;
};
@@ -587,25 +582,6 @@ static int rtnl_dellink(char *name)
return ret;
}

-static int netdev_noop(void *data)
-{
- return 0;
-}
-
-static int netdev_cleanup(void *data)
-{
- struct dq_netdev *dq = data;
-
- dev_put(dq->dev);
-
- if (dq->ctx->errno) {
- ckpt_debug("Unregistering netdev %s\n", dq->dev->name);
- unregister_netdev(dq->dev);
- }
-
- return 0;
-}
-
static struct net_device *restore_veth(struct ckpt_ctx *ctx,
struct ckpt_hdr_netdev *h,
struct net *net)
@@ -616,9 +592,6 @@ static struct net_device *restore_veth(struct ckpt_ctx *ctx,
struct net_device *dev;
struct net_device *peer;
struct ifreq req;
- struct dq_netdev dq;
-
- dq.ctx = ctx;

ret = _ckpt_read_buffer(ctx, this_name, IFNAMSIZ);
if (ret < 0)
@@ -640,37 +613,31 @@ static struct net_device *restore_veth(struct ckpt_ctx *ctx,
if (IS_ERR(dev))
return dev;

+ ret = ckpt_obj_insert(ctx, dev, h->veth.this_ref,
+ CKPT_OBJ_NETDEV);
+ dev_put(dev);
+ if (ret < 0)
+ goto err;
+
peer = dev_get_by_name(current->nsproxy->net_ns, peer_name);
if (!peer) {
ret = -EINVAL;
- goto err_dev;
+ goto err;
}

- dq.dev = peer;
- ret = deferqueue_add(ctx->deferqueue, &dq, sizeof(dq),
- netdev_noop, netdev_cleanup);
- if (ret)
- goto err_peer;
-
ret = ckpt_obj_insert(ctx, peer, h->veth.peer_ref,
CKPT_OBJ_NETDEV);
- if (ret < 0)
- /* Can't recall peer dq, so let it cleanup peer */
- goto err_dev;
dev_put(peer);
-
- dq.dev = dev;
- ret = deferqueue_add(ctx->deferqueue, &dq, sizeof(dq),
- netdev_noop, netdev_cleanup);
- if (ret)
- /* Can't recall peer dq, so let it cleanup peer */
- goto err_dev;
+ if (ret < 0)
+ goto err;

} else {
/* We're second: get our dev from the hash */
dev = ckpt_obj_fetch(ctx, h->veth.this_ref, CKPT_OBJ_NETDEV);
- if (IS_ERR(dev))
- return dev;
+ if (IS_ERR(dev)) {
+ ret = PTR_ERR(dev);
+ goto err;
+ }
}

/* Move to our new netns */
@@ -678,25 +645,31 @@ static struct net_device *restore_veth(struct ckpt_ctx *ctx,
ret = dev_change_net_namespace(dev, net, dev->name);
rtnl_unlock();
if (ret < 0)
- goto out;
+ goto err;

/* Restore MAC address */
memcpy(req.ifr_name, dev->name, IFNAMSIZ);
memcpy(req.ifr_hwaddr.sa_data, h->hwaddr, sizeof(h->hwaddr));
req.ifr_hwaddr.sa_family = ARPHRD_ETHER;
ret = __kern_dev_ioctl(net, SIOCSIFHWADDR, &req);
- out:
- if (ret)
- dev = ERR_PTR(ret);
+ if (ret < 0)
+ goto err;

return dev;
-
- err_peer:
- dev_put(peer);
- unregister_netdev(peer);
- err_dev:
- dev_put(dev);
- unregister_netdev(dev);
+ err:
+ /* Delete from hash to drop reference */
+ ckpt_obj_delete(ctx, h->veth.this_ref, CKPT_OBJ_NETDEV);
+ ckpt_obj_delete(ctx, h->veth.peer_ref, CKPT_OBJ_NETDEV);
+
+ /* This will fail to delete the interface if we get here
+ * because of a failed attempt at setting the hardware
+ * address, since the device has been moved to another netns.
+ * This is not a problem, however, because the death of that
+ * netns will take the device (and its peer) down with it
+ * cleanly.
+ */
+ if (rtnl_dellink(this_name) < 0)
+ ckpt_debug("failed to delete interfaces on error\n");

return ERR_PTR(ret);
}
--
1.6.3.3


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