[PATCH rdma-next 6/7] RDMA/nldev: Add support for RDMA monitoring

[Michael Guralnik <michaelgur@nvidia.com>]

From: Chiara Meiohas <cmeiohas@nvidia.com>

Introduce a new netlink command to allow rdma event monitoring.
The rdma events supported now are IB device
registration/unregistration and net device attachment/detachment.

Example output of rdma monitor and the commands which trigger
the events:

$ rdma monitor
$ rmmod mlx5_ib
[UNREGISTER]    dev 3
[UNREGISTER]    dev 0

$modprobe mlx5_ib
[REGISTER]      dev 4
[NETDEV_ATTACH] dev 4 port 1 netdev 4
[REGISTER]      dev 5
[NETDEV_ATTACH] dev 5 port 1 netdev 5

$ devlink dev eswitch set pci/0000:08:00.0 mode switchdev
[UNREGISTER]    dev 4
[REGISTER]      dev 6
[NETDEV_ATTACH] dev 6 port 6 netdev 4

$ echo 4 > /sys/class/net/eth2/device/sriov_numvfs
[NETDEV_ATTACH] dev 6 port 2 netdev 7
[NETDEV_ATTACH] dev 6 port 3 netdev 8
[NETDEV_ATTACH] dev 6 port 4 netdev 9
[NETDEV_ATTACH] dev 6 port 5 netdev 10
[REGISTER]      dev 7
[NETDEV_ATTACH] dev 7 port 1 netdev 11
[REGISTER]      dev 8
[NETDEV_ATTACH] dev 8 port 1 netdev 12
[REGISTER]      dev 9
[NETDEV_ATTACH] dev 9 port 1 netdev 13
[REGISTER]      dev 10
[NETDEV_ATTACH] dev 10 port 1 netdev 14

$ echo 0 > /sys/class/net/eth2/device/sriov_numvfs
[UNREGISTER]    dev 7
[UNREGISTER]    dev 8
[UNREGISTER]    dev 9
[UNREGISTER]    dev 10
[NETDEV_DETACH] dev 6 port 2
[NETDEV_DETACH] dev 6 port 3
[NETDEV_DETACH] dev 6 port 4
[NETDEV_DETACH] dev 6 port 5

Signed-off-by: Chiara Meiohas <cmeiohas@nvidia.com>
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/core/device.c  |  38 ++++++++++
 drivers/infiniband/core/netlink.c |   1 +
 drivers/infiniband/core/nldev.c   | 117 ++++++++++++++++++++++++++++++
 include/rdma/rdma_netlink.h       |  10 +++
 include/uapi/rdma/rdma_netlink.h  |  15 ++++
 5 files changed, 181 insertions(+)

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index b2fc5a13577c..2113eb7c7573 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1351,6 +1351,30 @@ static void prevent_dealloc_device(struct ib_device *ib_dev)
 {
 }
 
+static void ib_device_notify_register(struct ib_device *device)
+{
+	struct net_device *netdev;
+	u32 port;
+	int ret;
+
+	ret = rdma_nl_notify_event(device, 0, RDMA_REGISTER_EVENT);
+	if (ret)
+		return;
+
+	rdma_for_each_port(device, port) {
+		netdev = ib_device_get_netdev(device, port);
+		if (!netdev)
+			continue;
+
+		ret = rdma_nl_notify_event(device, port,
+					   RDMA_NETDEV_ATTACH_EVENT);
+		dev_put(netdev);
+		if (ret)
+			return;
+	}
+	return;
+}
+
 /**
  * ib_register_device - Register an IB device with IB core
  * @device: Device to register
@@ -1449,6 +1473,8 @@ int ib_register_device(struct ib_device *device, const char *name,
 	dev_set_uevent_suppress(&device->dev, false);
 	/* Mark for userspace that device is ready */
 	kobject_uevent(&device->dev.kobj, KOBJ_ADD);
+
+	ib_device_notify_register(device);
 	ib_device_put(device);
 
 	return 0;
@@ -1491,6 +1517,7 @@ static void __ib_unregister_device(struct ib_device *ib_dev)
 		goto out;
 
 	disable_device(ib_dev);
+	rdma_nl_notify_event(ib_dev, 0, RDMA_UNREGISTER_EVENT);
 
 	/* Expedite removing unregistered pointers from the hash table */
 	free_netdevs(ib_dev);
@@ -2159,6 +2186,7 @@ static void add_ndev_hash(struct ib_port_data *pdata)
 int ib_device_set_netdev(struct ib_device *ib_dev, struct net_device *ndev,
 			 u32 port)
 {
+	enum rdma_nl_notify_event_type etype;
 	struct net_device *old_ndev;
 	struct ib_port_data *pdata;
 	unsigned long flags;
@@ -2190,6 +2218,16 @@ int ib_device_set_netdev(struct ib_device *ib_dev, struct net_device *ndev,
 	spin_unlock_irqrestore(&pdata->netdev_lock, flags);
 
 	add_ndev_hash(pdata);
+
+	down_read(&devices_rwsem);
+	if (xa_get_mark(&devices, ib_dev->index, DEVICE_REGISTERED) &&
+	    xa_load(&devices, ib_dev->index) == ib_dev) {
+		etype = ndev ?
+			RDMA_NETDEV_ATTACH_EVENT : RDMA_NETDEV_DETACH_EVENT;
+		rdma_nl_notify_event(ib_dev, port, etype);
+	}
+	up_read(&devices_rwsem);
+
 	return 0;
 }
 EXPORT_SYMBOL(ib_device_set_netdev);
diff --git a/drivers/infiniband/core/netlink.c b/drivers/infiniband/core/netlink.c
index ae2db0c70788..def14c54b648 100644
--- a/drivers/infiniband/core/netlink.c
+++ b/drivers/infiniband/core/netlink.c
@@ -311,6 +311,7 @@ int rdma_nl_net_init(struct rdma_dev_net *rnet)
 	struct net *net = read_pnet(&rnet->net);
 	struct netlink_kernel_cfg cfg = {
 		.input	= rdma_nl_rcv,
+		.flags = NL_CFG_F_NONROOT_RECV,
 	};
 	struct sock *nls;
 
diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
index 4d4a1f90e484..5acbde242b97 100644
--- a/drivers/infiniband/core/nldev.c
+++ b/drivers/infiniband/core/nldev.c
@@ -170,6 +170,7 @@ static const struct nla_policy nldev_policy[RDMA_NLDEV_ATTR_MAX] = {
 	[RDMA_NLDEV_ATTR_DEV_TYPE]		= { .type = NLA_U8 },
 	[RDMA_NLDEV_ATTR_PARENT_NAME]		= { .type = NLA_NUL_STRING },
 	[RDMA_NLDEV_ATTR_NAME_ASSIGN_TYPE]	= { .type = NLA_U8 },
+	[RDMA_NLDEV_ATTR_EVENT_TYPE]		= { .type = NLA_U8 },
 };
 
 static int put_driver_name_print_type(struct sk_buff *msg, const char *name,
@@ -2722,6 +2723,122 @@ static const struct rdma_nl_cbs nldev_cb_table[RDMA_NLDEV_NUM_OPS] = {
 	},
 };
 
+static int fill_mon_netdev_association(struct sk_buff *msg,
+				       struct ib_device *device, u32 port,
+				       const struct net *net)
+{
+	struct net_device *netdev = ib_device_get_netdev(device, port);
+	int ret = 0;
+
+	if (netdev && !net_eq(dev_net(netdev), net))
+		goto out;
+
+	ret = nla_put_u32(msg, RDMA_NLDEV_ATTR_DEV_INDEX, device->index);
+	if (ret)
+		goto out;
+	ret = nla_put_u32(msg, RDMA_NLDEV_ATTR_PORT_INDEX, port);
+	if (ret)
+		goto out;
+	if (netdev)
+		ret = nla_put_u32(msg, RDMA_NLDEV_ATTR_NDEV_INDEX,
+				  netdev->ifindex);
+
+out:
+	dev_put(netdev);
+	return ret;
+}
+
+static int fill_mon_register(struct sk_buff *msg, struct ib_device *device,
+			     const struct net *net)
+{
+	return nla_put_u32(msg, RDMA_NLDEV_ATTR_DEV_INDEX, device->index);
+}
+
+static void rdma_nl_notify_err_msg(struct ib_device *device, u32 port_num,
+				    enum rdma_nl_notify_event_type type)
+{
+	struct net_device *netdev;
+
+	switch (type) {
+	case RDMA_REGISTER_EVENT:
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor register device event\n");
+		break;
+	case RDMA_UNREGISTER_EVENT:
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor unregister device event\n");
+		break;
+	case RDMA_NETDEV_ATTACH_EVENT:
+		netdev = ib_device_get_netdev(device, port_num);
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor netdev attach event: port %d netdev %d\n",
+				     port_num, netdev->ifindex);
+		dev_put(netdev);
+		break;
+	case RDMA_NETDEV_DETACH_EVENT:
+		dev_warn_ratelimited(&device->dev,
+				     "Failed to send RDMA monitor netdev detach event: port %d\n",
+				     port_num);
+	default:
+		break;
+	};
+}
+
+int rdma_nl_notify_event(struct ib_device *device, u32 port_num,
+			  enum rdma_nl_notify_event_type type)
+{
+	struct sk_buff *skb;
+	struct net *net;
+	int ret = 0;
+	void *nlh;
+
+	net = read_pnet(&device->coredev.rdma_net);
+	if (!net)
+		return -EINVAL;
+
+	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+	nlh = nlmsg_put(skb, 0, 0,
+			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_MONITOR),
+			0, 0);
+
+	switch (type) {
+	case RDMA_REGISTER_EVENT:
+	case RDMA_UNREGISTER_EVENT:
+		ret = fill_mon_register(skb, device, net);
+		if (ret)
+			goto err_free;
+		break;
+	case RDMA_NETDEV_ATTACH_EVENT:
+	case RDMA_NETDEV_DETACH_EVENT:
+		ret = fill_mon_netdev_association(skb, device,
+						  port_num, net);
+		if (ret)
+			goto err_free;
+		break;
+	default:
+		goto err_free;
+	}
+
+	ret = nla_put_u8(skb, RDMA_NLDEV_ATTR_EVENT_TYPE, type);
+	if (ret)
+		goto err_free;
+
+	nlmsg_end(skb, nlh);
+	ret = rdma_nl_multicast(net, skb, RDMA_NL_GROUP_NOTIFY, GFP_KERNEL);
+	if (ret && ret != -ESRCH) {
+		skb = NULL; /* skb is freed in the netlink send-op handling */
+		goto err_free;
+	}
+	return 0;
+
+err_free:
+	rdma_nl_notify_err_msg(device, port_num, type);
+	nlmsg_free(skb);
+	return ret;
+}
+
 void __init nldev_init(void)
 {
 	rdma_nl_register(RDMA_NL_NLDEV, nldev_cb_table);
diff --git a/include/rdma/rdma_netlink.h b/include/rdma/rdma_netlink.h
index c2a79aeee113..a5b47ca4cd66 100644
--- a/include/rdma/rdma_netlink.h
+++ b/include/rdma/rdma_netlink.h
@@ -110,6 +110,16 @@ int rdma_nl_multicast(struct net *net, struct sk_buff *skb,
  */
 bool rdma_nl_chk_listeners(unsigned int group);
 
+/**
+ * Prepare and send an event message
+ * @ib: the IB device which triggered the event
+ * @port_num: the port number which triggered the event - 0 if unused
+ * @type: the event type
+ * Returns 0 on success or a negative error code
+ */
+int rdma_nl_notify_event(struct ib_device *ib, u32 port_num,
+			 enum rdma_nl_notify_event_type type);
+
 struct rdma_link_ops {
 	struct list_head list;
 	const char *type;
diff --git a/include/uapi/rdma/rdma_netlink.h b/include/uapi/rdma/rdma_netlink.h
index 2f37568f5556..5f9636d26050 100644
--- a/include/uapi/rdma/rdma_netlink.h
+++ b/include/uapi/rdma/rdma_netlink.h
@@ -15,6 +15,7 @@ enum {
 enum {
 	RDMA_NL_GROUP_IWPM = 2,
 	RDMA_NL_GROUP_LS,
+	RDMA_NL_GROUP_NOTIFY,
 	RDMA_NL_NUM_GROUPS
 };
 
@@ -305,6 +306,8 @@ enum rdma_nldev_command {
 
 	RDMA_NLDEV_CMD_DELDEV,
 
+	RDMA_NLDEV_CMD_MONITOR,
+
 	RDMA_NLDEV_NUM_OPS
 };
 
@@ -574,6 +577,8 @@ enum rdma_nldev_attr {
 
 	RDMA_NLDEV_ATTR_NAME_ASSIGN_TYPE,	/* u8 */
 
+	RDMA_NLDEV_ATTR_EVENT_TYPE,		/* u8 */
+
 	/*
 	 * Always the end
 	 */
@@ -624,4 +629,14 @@ enum rdma_nl_name_assign_type {
 	RDMA_NAME_ASSIGN_TYPE_USER = 1, /* Provided by user-space */
 };
 
+/*
+ * Supported rdma monitoring event types.
+ */
+enum rdma_nl_notify_event_type {
+	RDMA_REGISTER_EVENT,
+	RDMA_UNREGISTER_EVENT,
+	RDMA_NETDEV_ATTACH_EVENT,
+	RDMA_NETDEV_DETACH_EVENT,
+};
+
 #endif /* _UAPI_RDMA_NETLINK_H */
-- 
2.17.2