Subject: [PATCHv4 net-next] xfrm: Namespacify xfrm_policy_sk_bundles

From: Fan Du <[email-masked]>
Date: Fri, 20 Dec 2013 11:34:41 +0800

On 2013年12月19日 11:44, Eric Dumazet wrote:
> On Thu, 2013-12-19 at 11:17 +0800, Fan Du wrote:
>>
>
>> diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
>> index 1006a26..22f4f90 100644
>> --- a/include/net/netns/xfrm.h
>> +++ b/include/net/netns/xfrm.h
>> @@ -58,9 +58,9 @@ struct netns_xfrm {
>>    	struct dst_ops		xfrm6_dst_ops;
>>    #endif
>>    	spinlock_t xfrm_state_lock;
>> -	spinlock_t xfrm_policy_sk_bundle_lock;
>>    	rwlock_t xfrm_policy_lock;
>>    	struct mutex xfrm_cfg_mutex;
>> +	struct llist_head xp_sk_bundles_list;
>>    };
>>
>>    #endif
>> diff --git a/include/net/xfrm.h b/include/net/xfrm.h
>> index 59f5d0a..05296ab 100644
>> --- a/include/net/xfrm.h
>> +++ b/include/net/xfrm.h
>> @@ -957,6 +957,7 @@ struct xfrm_dst {
>>    	u32 child_mtu_cached;
>>    	u32 route_cookie;
>>    	u32 path_cookie;
>> +	struct llist_node       xdst_llist;
>>    };
>>
>
> Hmm... Thats not very nice.
>
> Please reuse the storage adding a llist_node in the union ?
>
> diff --git a/include/net/dst.h b/include/net/dst.h
> index 44995c13e941..3f604f47cc58 100644
> --- a/include/net/dst.h
> +++ b/include/net/dst.h
> @@ -14,6 +14,7 @@
>   #include<linux/rcupdate.h>
>   #include<linux/bug.h>
>   #include<linux/jiffies.h>
> +#include<linux/llist.h>
>   #include<net/neighbour.h>
>   #include<asm/processor.h>
>
> @@ -103,6 +104,7 @@ struct dst_entry {
>   		struct rtable __rcu	*rt_next;
>   		struct rt6_info		*rt6_next;
>   		struct dn_route __rcu	*dn_next;
> +		struct llist_node	llist;
>   	};
>   };

Hi, Eric

You are correct on this, have fix the patch wrt your comments.
Thank you very much.

 From 1b929e1cdea978d0c8d10d731af84969bd37004b Mon Sep 17 00:00:00 2001
From: Fan Du <[email-masked]>
Date: Fri, 20 Dec 2013 11:23:27 +0800
Subject: [PATCHv4 net-next] xfrm: Namespacify xfrm_policy_sk_bundles

xfrm_policy_sk_bundles, protected by net->xfrm.xfrm_policy_sk_bundle_lock
should be put into netns xfrm structure, otherwise xfrm_policy_sk_bundles
can be corrupted from different net namespace.

Moreover current xfrm_policy_sk_bundle_lock used in below two scenarios:

1. xfrm_lookup(Process context)  vs  __xfrm_garbage_collect(softirq context)
2. xfrm_lookup(Process context)  vs  __xfrm_garbage_collect(Process context
                                                 when SPD change or dev down)

We can use lock less list to cater to those two scenarios as suggested by
Eric Dumazet.

Signed-off-by: Fan Du <[email-masked]>
Assisted-by: Eric Dumazet <[email-masked]>
---
v2:
   Fix incorrect commit log.

v3:
   Drop xchg, use llist instead, adviced by Eric Dumazet.

v4:
  Incorporate Eric's comments.
   -Union llist with dst_entry->next, which is used for queuing previous,
    then it's safe to do so.
   -Use llist_for_each_entry_safe for purging list.
   -Rebase with net-next, as ipsec-next got pulled.

---
  include/net/dst.h        |    5 +++++
  include/net/netns/xfrm.h |    2 +-
  net/xfrm/xfrm_policy.c   |   26 ++++++--------------------
  3 files changed, 12 insertions(+), 21 deletions(-)

diff --git a/include/net/dst.h b/include/net/dst.h
index 77eb53f..e9b81f0 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -14,6 +14,7 @@
  #include <linux/rcupdate.h>
  #include <linux/bug.h>
  #include <linux/jiffies.h>
+#include <linux/llist.h>
  #include <net/neighbour.h>
  #include <asm/processor.h>

@@ -103,6 +104,10 @@ struct dst_entry {
  		struct rtable __rcu	*rt_next;
  		struct rt6_info		*rt6_next;
  		struct dn_route __rcu	*dn_next;
+#ifdef CONFIG_XFRM		
+		/* Used to queue each policy sk dst */
+		struct llist_node       llist;
+#endif
  	};
  };

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 1006a26..22f4f90 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -58,9 +58,9 @@ struct netns_xfrm {
  	struct dst_ops		xfrm6_dst_ops;
  #endif
  	spinlock_t xfrm_state_lock;
-	spinlock_t xfrm_policy_sk_bundle_lock;
  	rwlock_t xfrm_policy_lock;
  	struct mutex xfrm_cfg_mutex;
+	struct llist_head xp_sk_bundles_list;
  };

  #endif
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index a7487f3..0cc7446 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -39,8 +39,6 @@
  #define XFRM_QUEUE_TMO_MAX ((unsigned)(60*HZ))
  #define XFRM_MAX_QUEUE_LEN	100

-static struct dst_entry *xfrm_policy_sk_bundles;
-
  static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
  static struct xfrm_policy_afinfo __rcu *xfrm_policy_afinfo[NPROTO]
  						__read_mostly;
@@ -2108,12 +2106,7 @@ struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
  			}

  			dst_hold(&xdst->u.dst);
-
-			spin_lock_bh(&net->xfrm.xfrm_policy_sk_bundle_lock);
-			xdst->u.dst.next = xfrm_policy_sk_bundles;
-			xfrm_policy_sk_bundles = &xdst->u.dst;
-			spin_unlock_bh(&net->xfrm.xfrm_policy_sk_bundle_lock);
-
+			llist_add(&xdst->u.dst.llist, &net->xfrm.xp_sk_bundles_list);
  			route = xdst->route;
  		}
  	}
@@ -2549,18 +2542,12 @@ static struct dst_entry *xfrm_negative_advice(struct dst_entry *dst)

  static void __xfrm_garbage_collect(struct net *net)
  {
-	struct dst_entry *head, *next;
+	struct llist_node *head;
+	struct dst_entry *dst, *tmp;

-	spin_lock_bh(&net->xfrm.xfrm_policy_sk_bundle_lock);
-	head = xfrm_policy_sk_bundles;
-	xfrm_policy_sk_bundles = NULL;
-	spin_unlock_bh(&net->xfrm.xfrm_policy_sk_bundle_lock);
-
-	while (head) {
-		next = head->next;
-		dst_free(head);
-		head = next;
-	}
+	head = llist_del_all(&net->xfrm.xp_sk_bundles_list);
+	llist_for_each_entry_safe(dst, tmp, head, llist)
+		dst_free(dst);
  }

  void xfrm_garbage_collect(struct net *net)
@@ -2942,7 +2929,6 @@ static int __net_init xfrm_net_init(struct net *net)
  	/* Initialize the per-net locks here */
  	spin_lock_init(&net->xfrm.xfrm_state_lock);
  	rwlock_init(&net->xfrm.xfrm_policy_lock);
-	spin_lock_init(&net->xfrm.xfrm_policy_sk_bundle_lock);
  	mutex_init(&net->xfrm.xfrm_cfg_mutex);

  	return 0;
-- 
1.7.9.5

-- 
浮沉随浪只记今朝笑

--fan