Merge branch 'resil-nhgroups-netdevsim-selftests'

Petr Machata says:

====================
net: Resilient NH groups: netdevsim, selftests

Support for resilient next-hop groups was added in a previous patch set.
Resilient next hop groups add a layer of indirection between the SKB hash
and the next hop. Thus the hash is used to reference a hash table bucket,
which is then used to reference a particular next hop. This allows the
system more flexibility when assigning SKB hash space to next hops.
Previously, each next hop had to be assigned a continuous range of SKB hash
space. With a hash table as an intermediate layer, it is possible to
reassign next hops with a hash table bucket granularity. In turn, this
mends issues with traffic flow redirection resulting from next hop removal
or adjustments in next-hop weights.

This patch set introduces mock offloading of resilient next hop groups by
the netdevsim driver, and a suite of selftests.

- Patch #1 adds a netdevsim-specific lock to protect next-hop hashtable.
  Previously, netdevsim relied on RTNL to maintain mutual exclusion.
  Patch #2 extracts a helper to make the following patches clearer.

- Patch #3 implements the support for offloading of resilient next-hop
  groups.

- Patch #4 introduces a new debugfs interface to set activity on a selected
  next-hop bucket. This simulates how HW can periodically report bucket
  activity, and buckets thus marked are expected to be exempt from
  migration to new next hops when the group changes.

- Patches #5 and #6 clean up the fib_nexthop selftests.

- Patches #7, #8 and #9 add tests for resilient next hop groups. Patch #7
  adds resilient-hashing counterparts to fib_nexthops.sh. Patch #8 adds a
  new traffic test for resilient next-hop groups. Patch #9 adds a new
  traffic test for tunneling.

- Patch #10 actually leverages the netdevsim offload to implement a suite
  of algorithmic tests that verify how and when buckets are migrated under
  various simulated workload scenarios.

The overall plan is to contribute approximately the following patchsets:

1) Nexthop policy refactoring (already pushed)
2) Preparations for resilient next hop groups (already pushed)
3) Implementation of resilient next hop group (already pushed)
4) Netdevsim offload plus a suite of selftests (this patchset)
5) Preparations for mlxsw offload of resilient next-hop groups
6) mlxsw offload including selftests

Interested parties can look at the complete code at [2].

[1] https://tools.ietf.org/html/rfc2992
[2] https://github.com/idosch/linux/commits/submit/res_integ_v1
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netdevsim/fib.c

@@ -14,6 +14,7 @@
  * THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
  */
 
+#include <linux/bitmap.h>
 #include <linux/in6.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
@@ -47,15 +48,18 @@ struct nsim_fib_data {
 	struct nsim_fib_entry nexthops;
 	struct rhashtable fib_rt_ht;
 	struct list_head fib_rt_list;
-	struct mutex fib_lock; /* Protects hashtable and list */
+	struct mutex fib_lock; /* Protects FIB HT and list */
 	struct notifier_block nexthop_nb;
 	struct rhashtable nexthop_ht;
 	struct devlink *devlink;
 	struct work_struct fib_event_work;
 	struct list_head fib_event_queue;
 	spinlock_t fib_event_queue_lock; /* Protects fib event queue list */
+	struct mutex nh_lock; /* Protects NH HT */
 	struct dentry *ddir;
 	bool fail_route_offload;
+	bool fail_res_nexthop_group_replace;
+	bool fail_nexthop_bucket_replace;
 };
 
 struct nsim_fib_rt_key {
@@ -116,6 +120,7 @@ struct nsim_nexthop {
 	struct rhash_head ht_node;
 	u64 occ;
 	u32 id;
+	bool is_resilient;
 };
 
 static const struct rhashtable_params nsim_nexthop_ht_params = {
@@ -1114,6 +1119,10 @@ static struct nsim_nexthop *nsim_nexthop_create(struct nsim_fib_data *data,
 		for (i = 0; i < info->nh_grp->num_nh; i++)
 			occ += info->nh_grp->nh_entries[i].weight;
 		break;
+	case NH_NOTIFIER_INFO_TYPE_RES_TABLE:
+		occ = info->nh_res_table->num_nh_buckets;
+		nexthop->is_resilient = true;
+		break;
 	default:
 		NL_SET_ERR_MSG_MOD(info->extack, "Unsupported nexthop type");
 		kfree(nexthop);
@@ -1156,6 +1165,21 @@ static int nsim_nexthop_account(struct nsim_fib_data *data, u64 occ,
 
 }
 
+static void nsim_nexthop_hw_flags_set(struct net *net,
+				      const struct nsim_nexthop *nexthop,
+				      bool trap)
+{
+	int i;
+
+	nexthop_set_hw_flags(net, nexthop->id, false, trap);
+
+	if (!nexthop->is_resilient)
+		return;
+
+	for (i = 0; i < nexthop->occ; i++)
+		nexthop_bucket_set_hw_flags(net, nexthop->id, i, false, trap);
+}
+
 static int nsim_nexthop_add(struct nsim_fib_data *data,
 			    struct nsim_nexthop *nexthop,
 			    struct netlink_ext_ack *extack)
@@ -1174,7 +1198,7 @@ static int nsim_nexthop_add(struct nsim_fib_data *data,
 		goto err_nexthop_dismiss;
 	}
 
-	nexthop_set_hw_flags(net, nexthop->id, false, true);
+	nsim_nexthop_hw_flags_set(net, nexthop, true);
 
 	return 0;
 
@@ -1203,7 +1227,7 @@ static int nsim_nexthop_replace(struct nsim_fib_data *data,
 		goto err_nexthop_dismiss;
 	}
 
-	nexthop_set_hw_flags(net, nexthop->id, false, true);
+	nsim_nexthop_hw_flags_set(net, nexthop, true);
 	nsim_nexthop_account(data, nexthop_old->occ, false, extack);
 	nsim_nexthop_destroy(nexthop_old);
 
@@ -1254,6 +1278,32 @@ static void nsim_nexthop_remove(struct nsim_fib_data *data,
 	nsim_nexthop_destroy(nexthop);
 }
 
+static int nsim_nexthop_res_table_pre_replace(struct nsim_fib_data *data,
+					      struct nh_notifier_info *info)
+{
+	if (data->fail_res_nexthop_group_replace) {
+		NL_SET_ERR_MSG_MOD(info->extack, "Failed to replace a resilient nexthop group");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int nsim_nexthop_bucket_replace(struct nsim_fib_data *data,
+				       struct nh_notifier_info *info)
+{
+	if (data->fail_nexthop_bucket_replace) {
+		NL_SET_ERR_MSG_MOD(info->extack, "Failed to replace nexthop bucket");
+		return -EINVAL;
+	}
+
+	nexthop_bucket_set_hw_flags(info->net, info->id,
+				    info->nh_res_bucket->bucket_index,
+				    false, true);
+
+	return 0;
+}
+
 static int nsim_nexthop_event_nb(struct notifier_block *nb, unsigned long event,
 				 void *ptr)
 {
@@ -1262,19 +1312,25 @@ static int nsim_nexthop_event_nb(struct notifier_block *nb, unsigned long event,
 	struct nh_notifier_info *info = ptr;
 	int err = 0;
 
-	ASSERT_RTNL();
-
+	mutex_lock(&data->nh_lock);
 	switch (event) {
 	case NEXTHOP_EVENT_REPLACE:
 		err = nsim_nexthop_insert(data, info);
 		break;
 	case NEXTHOP_EVENT_DEL:
 		nsim_nexthop_remove(data, info);
 		break;
+	case NEXTHOP_EVENT_RES_TABLE_PRE_REPLACE:
+		err = nsim_nexthop_res_table_pre_replace(data, info);
+		break;
+	case NEXTHOP_EVENT_BUCKET_REPLACE:
+		err = nsim_nexthop_bucket_replace(data, info);
+		break;
 	default:
 		break;
 	}
 
+	mutex_unlock(&data->nh_lock);
 	return notifier_from_errno(err);
 }
 
@@ -1285,11 +1341,68 @@ static void nsim_nexthop_free(void *ptr, void *arg)
 	struct net *net;
 
 	net = devlink_net(data->devlink);
-	nexthop_set_hw_flags(net, nexthop->id, false, false);
+	nsim_nexthop_hw_flags_set(net, nexthop, false);
 	nsim_nexthop_account(data, nexthop->occ, false, NULL);
 	nsim_nexthop_destroy(nexthop);
 }
 
+static ssize_t nsim_nexthop_bucket_activity_write(struct file *file,
+						  const char __user *user_buf,
+						  size_t size, loff_t *ppos)
+{
+	struct nsim_fib_data *data = file->private_data;
+	struct net *net = devlink_net(data->devlink);
+	struct nsim_nexthop *nexthop;
+	unsigned long *activity;
+	loff_t pos = *ppos;
+	u16 bucket_index;
+	char buf[128];
+	int err = 0;
+	u32 nhid;
+
+	if (pos != 0)
+		return -EINVAL;
+	if (size > sizeof(buf))
+		return -EINVAL;
+	if (copy_from_user(buf, user_buf, size))
+		return -EFAULT;
+	if (sscanf(buf, "%u %hu", &nhid, &bucket_index) != 2)
+		return -EINVAL;
+
+	rtnl_lock();
+
+	nexthop = rhashtable_lookup_fast(&data->nexthop_ht, &nhid,
+					 nsim_nexthop_ht_params);
+	if (!nexthop || !nexthop->is_resilient ||
+	    bucket_index >= nexthop->occ) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	activity = bitmap_zalloc(nexthop->occ, GFP_KERNEL);
+	if (!activity) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	bitmap_set(activity, bucket_index, 1);
+	nexthop_res_grp_activity_update(net, nhid, nexthop->occ, activity);
+	bitmap_free(activity);
+
+out:
+	rtnl_unlock();
+
+	*ppos = size;
+	return err ?: size;
+}
+
+static const struct file_operations nsim_nexthop_bucket_activity_fops = {
+	.open = simple_open,
+	.write = nsim_nexthop_bucket_activity_write,
+	.llseek = no_llseek,
+	.owner = THIS_MODULE,
+};
+
 static u64 nsim_fib_ipv4_resource_occ_get(void *priv)
 {
 	struct nsim_fib_data *data = priv;
@@ -1379,6 +1492,17 @@ nsim_fib_debugfs_init(struct nsim_fib_data *data, struct nsim_dev *nsim_dev)
 	data->fail_route_offload = false;
 	debugfs_create_bool("fail_route_offload", 0600, data->ddir,
 			    &data->fail_route_offload);
+
+	data->fail_res_nexthop_group_replace = false;
+	debugfs_create_bool("fail_res_nexthop_group_replace", 0600, data->ddir,
+			    &data->fail_res_nexthop_group_replace);
+
+	data->fail_nexthop_bucket_replace = false;
+	debugfs_create_bool("fail_nexthop_bucket_replace", 0600, data->ddir,
+			    &data->fail_nexthop_bucket_replace);
+
+	debugfs_create_file("nexthop_bucket_activity", 0200, data->ddir,
+			    data, &nsim_nexthop_bucket_activity_fops);
 	return 0;
 }
 
@@ -1404,6 +1528,7 @@ struct nsim_fib_data *nsim_fib_create(struct devlink *devlink,
 	if (err)
 		goto err_data_free;
 
+	mutex_init(&data->nh_lock);
 	err = rhashtable_init(&data->nexthop_ht, &nsim_nexthop_ht_params);
 	if (err)
 		goto err_debugfs_exit;
@@ -1469,6 +1594,7 @@ struct nsim_fib_data *nsim_fib_create(struct devlink *devlink,
 				    data);
 	mutex_destroy(&data->fib_lock);
 err_debugfs_exit:
+	mutex_destroy(&data->nh_lock);
 	nsim_fib_debugfs_exit(data);
 err_data_free:
 	kfree(data);
@@ -1497,6 +1623,7 @@ void nsim_fib_destroy(struct devlink *devlink, struct nsim_fib_data *data)
 	WARN_ON_ONCE(!list_empty(&data->fib_event_queue));
 	WARN_ON_ONCE(!list_empty(&data->fib_rt_list));
 	mutex_destroy(&data->fib_lock);
+	mutex_destroy(&data->nh_lock);
 	nsim_fib_debugfs_exit(data);
 	kfree(data);
 }