1 files changed, 84 insertions, 0 deletions

diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
index 630d1eeecf2a..e5c7f078fbd4 100644
--- a/net/core/page_pool_user.c
+++ b/net/core/page_pool_user.c
@@ -1,14 +1,31 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/mutex.h>
+#include <linux/netdevice.h>
 #include <linux/xarray.h>
+#include <net/net_debug.h>
 #include <net/page_pool/types.h>
 
 #include "page_pool_priv.h"
 
 static DEFINE_XARRAY_FLAGS(page_pools, XA_FLAGS_ALLOC1);
+/* Protects: page_pools, netdevice->page_pools, pool->slow.netdev, pool->user.
+ * Ordering: inside rtnl_lock
+ */
 static DEFINE_MUTEX(page_pools_lock);
 
+/* Page pools are only reachable from user space (via netlink) if they are
+ * linked to a netdev at creation time. Following page pool "visibility"
+ * states are possible:
+ *  - normal
+ *    - user.list: linked to real netdev, netdev: real netdev
+ *  - orphaned - real netdev has disappeared
+ *    - user.list: linked to lo, netdev: lo
+ *  - invisible - either (a) created without netdev linking, (b) unlisted due
+ *      to error, or (c) the entire namespace which owned this pool disappeared
+ *    - user.list: unhashed, netdev: unknown
+ */
+
 int page_pool_list(struct page_pool *pool)
 {
 	static u32 id_alloc_next;
@@ -20,6 +37,10 @@ int page_pool_list(struct page_pool *pool)
 	if (err < 0)
 		goto err_unlock;
 
+	if (pool->slow.netdev)
+		hlist_add_head(&pool->user.list,
+			       &pool->slow.netdev->page_pools);
+
 	mutex_unlock(&page_pools_lock);
 	return 0;
 
@@ -32,5 +53,68 @@ void page_pool_unlist(struct page_pool *pool)
 {
 	mutex_lock(&page_pools_lock);
 	xa_erase(&page_pools, pool->user.id);
+	hlist_del(&pool->user.list);
+	mutex_unlock(&page_pools_lock);
+}
+
+static void page_pool_unreg_netdev_wipe(struct net_device *netdev)
+{
+	struct page_pool *pool;
+	struct hlist_node *n;
+
+	mutex_lock(&page_pools_lock);
+	hlist_for_each_entry_safe(pool, n, &netdev->page_pools, user.list) {
+		hlist_del_init(&pool->user.list);
+		pool->slow.netdev = NET_PTR_POISON;
+	}
+	mutex_unlock(&page_pools_lock);
+}
+
+static void page_pool_unreg_netdev(struct net_device *netdev)
+{
+	struct page_pool *pool, *last;
+	struct net_device *lo;
+
+	lo = dev_net(netdev)->loopback_dev;
+
+	mutex_lock(&page_pools_lock);
+	last = NULL;
+	hlist_for_each_entry(pool, &netdev->page_pools, user.list) {
+		pool->slow.netdev = lo;
+		last = pool;
+	}
+	if (last)
+		hlist_splice_init(&netdev->page_pools, &last->user.list,
+				  &lo->page_pools);
 	mutex_unlock(&page_pools_lock);
 }
+
+static int
+page_pool_netdevice_event(struct notifier_block *nb,
+			  unsigned long event, void *ptr)
+{
+	struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
+
+	if (event != NETDEV_UNREGISTER)
+		return NOTIFY_DONE;
+
+	if (hlist_empty(&netdev->page_pools))
+		return NOTIFY_OK;
+
+	if (netdev->ifindex != LOOPBACK_IFINDEX)
+		page_pool_unreg_netdev(netdev);
+	else
+		page_pool_unreg_netdev_wipe(netdev);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block page_pool_netdevice_nb = {
+	.notifier_call = page_pool_netdevice_event,
+};
+
+static int __init page_pool_user_init(void)
+{
+	return register_netdevice_notifier(&page_pool_netdevice_nb);
+}
+
+subsys_initcall(page_pool_user_init);