make netns cleanup to run in a separate workqueue

Subject: make netns cleanup to run in a separate queue
From: Benjamin Thery <benjamin.thery-6ktuUTfB/[email protected]>

This patch adds a separate workqueue for cleaning up a network namespace. If we use the keventd workqueue to execute cleanup_net(), there is a problem to unregister devices in IPv6. Indeed the code that cleans up also schedule work in keventd: as long as cleanup_net() hasn't return, dst_gc_task() cannot run and as long as dst_gc_task() has not run, there are still some references pending on the net devices and cleanup_net() can not unregister and exit the keventd workqueue.

Signed-off-by Daniel Lezcano <dlezcano-NmTC/[email protected]>

Signed-off-by Benjamin Thery <benjamin.thery-6ktuUTfB/[email protected]>

Acked-by Denis V. Lunev <[email protected]>

---
 net/core/net_namespace.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Index: net-2.6.25/net/core/net_namespace.c
===================================================================

net/core/net_namespace.c +8 -2

@@ -58,6 +58,7 @@ out_undo:
 
 #ifdef CONFIG_NET_NS
 static struct kmem_cache *net_cachep;
+static struct workqueue_struct *netns_wq;
 
 static struct net *net_alloc(void)
 {

@@ -149,7 +150,7 @@ void __put_net(struct net *net)
 {
 	/* Cleanup the network namespace in process context */
 	INIT_WORK(&net->work, cleanup_net);
-	schedule_work(&net->work);
+	queue_work(netns_wq, &net->work);
 }
 EXPORT_SYMBOL_GPL(__put_net);
 

@@ -171,7 +172,13 @@ static int __init net_ns_init(void)
 	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
 					SMP_CACHE_BYTES,
 					SLAB_PANIC, NULL);
+
+	/* Create workqueue for cleanup */
+	netns_wq = create_singlethread_workqueue("netns");
+	if (!netns_wq)
+		panic("Could not create netns workq");
 
 #endif
+
 	mutex_lock(&net_mutex);
 	err = setup_net(&init_net);
 
 
 
------------------------------------------------------------------------

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imho panic() is too much.
create_singlethread_workqueue() can fail e.g. due to out of memory...

Thanks,
Kirill

Quoted 57 lines · Daniel Lezcano

Subject: make netns cleanup to run in a separate queue
From: Benjamin Thery <[email protected]>

This patch adds a separate workqueue for cleaning up a network namespace. If we use the keventd workqueue to execute cleanup_net(), there is a problem to unregister devices in IPv6. Indeed the code that cleans up also schedule work in keventd: as long as cleanup_net() hasn't return, dst_gc_task() cannot run and as long as dst_gc_task() has not run, there are still some references pending on the net devices and cleanup_net() can not unregister and exit the keventd workqueue.

Signed-off-by Daniel Lezcano <[email protected]>

Signed-off-by Benjamin Thery <[email protected]>

Acked-by Denis V. Lunev <[email protected]>

---
net/core/net_namespace.c | 9 ++++++++-

1 file changed, 8 insertions(+), 1 deletion(-)

Index: net-2.6.25/net/core/net_namespace.c
===================================================================

net/core/net_namespace.c +8 -1

@@ -58,6 +58,7 @@ out_undo:
 
 #ifdef CONFIG_NET_NS
 static struct kmem_cache *net_cachep;
+static struct workqueue_struct *netns_wq;
 
 static struct net *net_alloc(void)
 {

@@ -149,7 +150,7 @@ void __put_net(struct net *net)
 {
 	/* Cleanup the network namespace in process context */
 	INIT_WORK(&net->work, cleanup_net);
-	schedule_work(&net->work);
+	queue_work(netns_wq, &net->work);
 }
 EXPORT_SYMBOL_GPL(__put_net);
 

@@ -171,7 +172,13 @@ static int __init net_ns_init(void)
 	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
 					SMP_CACHE_BYTES,
 					SLAB_PANIC, NULL);
+
+	/* Create workqueue for cleanup */
+	netns_wq = create_singlethread_workqueue("netns");
+	if (!netns_wq)
+		panic("Could not create netns workq");
 
 
 #endif
+
 	mutex_lock(&net_mutex);

	err = setup_net(&init_net);

Quoted 6 lines

------------------------------------------------------------------------

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_______________________________________________
Containers mailing list
[email protected]
https://lists.linux-foundation.org/mailman/listinfo/containers

Acked-by Kirill Korotaev <[email protected]>