net-shapers: implement shaper cleanup on queue deletion

JIRA: https://issues.redhat.com/browse/RHEL-89973

commit ff7d4de
Author: Paolo Abeni <pabeni@redhat.com>
Date:   Wed Oct 9 10:09:53 2024 +0200

    net-shapers: implement shaper cleanup on queue deletion
    
    hook into netif_set_real_num_tx_queues() to cleanup any shaper
    configured on top of the to-be-destroyed TX queues.
    
    Reviewed-by: Jiri Pirko <jiri@nvidia.com>
    Reviewed-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>
    Link: https://patch.msgid.link/6da4ee03cae2b2a757d7b59e88baf09cc94c5ef1.1728460186.git.pabeni@redhat.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>

Author: jtornosm

net/core/dev.c

@@ -3006,6 +3006,8 @@ int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
 		if (dev->num_tc)
 			netif_setup_tc(dev, txq);
 
+		net_shaper_set_real_num_tx_queues(dev, txq);
+
 		dev_qdisc_change_real_num_tx(dev, txq);
 
 		dev->real_num_tx_queues = txq;

net/core/dev.h

@@ -41,8 +41,12 @@ int dev_addr_init(struct net_device *dev);
 
 #if IS_ENABLED(CONFIG_NET_SHAPER)
 void net_shaper_flush_netdev(struct net_device *dev);
+void net_shaper_set_real_num_tx_queues(struct net_device *dev,
+				       unsigned int txq);
 #else
 static inline void net_shaper_flush_netdev(struct net_device *dev) {}
+static inline void net_shaper_set_real_num_tx_queues(struct net_device *dev,
+						     unsigned int txq) {}
 #endif
 
 /* sysctls not referred to from outside net/core/ */

net/shaper/shaper.c

@@ -1157,6 +1157,54 @@ void net_shaper_flush_netdev(struct net_device *dev)
 	net_shaper_flush(&binding);
 }
 
+void net_shaper_set_real_num_tx_queues(struct net_device *dev,
+				       unsigned int txq)
+{
+	struct net_shaper_hierarchy *hierarchy;
+	struct net_shaper_binding binding;
+	int i;
+
+	binding.type = NET_SHAPER_BINDING_TYPE_NETDEV;
+	binding.netdev = dev;
+	hierarchy = net_shaper_hierarchy(&binding);
+	if (!hierarchy)
+		return;
+
+	/* Only drivers implementing shapers support ensure
+	 * the lock is acquired in advance.
+	 */
+	lockdep_assert_held(&dev->lock);
+
+	/* Take action only when decreasing the tx queue number. */
+	for (i = txq; i < dev->real_num_tx_queues; ++i) {
+		struct net_shaper_handle handle, parent_handle;
+		struct net_shaper *shaper;
+		u32 index;
+
+		handle.scope = NET_SHAPER_SCOPE_QUEUE;
+		handle.id = i;
+		shaper = net_shaper_lookup(&binding, &handle);
+		if (!shaper)
+			continue;
+
+		/* Don't touch the H/W for the queue shaper, the drivers already
+		 * deleted the queue and related resources.
+		 */
+		parent_handle = shaper->parent;
+		index = net_shaper_handle_to_index(&handle);
+		xa_erase(&hierarchy->shapers, index);
+		kfree_rcu(shaper, rcu);
+
+		/* The recursion on parent does the full job. */
+		if (parent_handle.scope != NET_SHAPER_SCOPE_NODE)
+			continue;
+
+		shaper = net_shaper_lookup(&binding, &parent_handle);
+		if (shaper && !--shaper->leaves)
+			__net_shaper_delete(&binding, shaper, NULL);
+	}
+}
+
 static int __init shaper_init(void)
 {
 	return genl_register_family(&net_shaper_nl_family);