From: Ying Xue <ying....@windriver.com>
After a subscription object is created, it's inserted into its
subscriber subscrp_list list under subscriber lock protection,
similarly, before it's destroyed, it should be first removed from
its subscriber->subscrp_list. Since the subscription list is
accessed with subscriber lock, all the subscriptions are valid
during the lock duration. Hence in tipc_subscrb_subscrp_delete(), we
remove subscription get/put and the extra subscriber unlock/lock.
After this change, the subscriptions refcount cleanup is very simple
and does not access any lock.
Signed-off-by: Ying Xue <ying....@windriver.com>
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvara...@ericsson.com>
---
v2: Remove the subscrp_list at tipc_subscrp_timeout() also. This
prevents any subscription cancel or subscriber delete thread
running in parallel seeing the timeout out subscription.
---
net/tipc/subscr.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index 271cd66e4b3b..0649bc29c6bb 100644
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -145,6 +145,7 @@ static void tipc_subscrp_timeout(unsigned long data)
spin_lock_bh(&subscriber->lock);
tipc_nametbl_unsubscribe(sub);
+ list_del(&sub->subscrp_list);
spin_unlock_bh(&subscriber->lock);
/* Notify subscriber of timeout */
@@ -177,10 +178,7 @@ static void tipc_subscrp_kref_release(struct kref *kref)
struct tipc_net *tn = net_generic(sub->net, tipc_net_id);
struct tipc_subscriber *subscriber = sub->subscriber;
- spin_lock_bh(&subscriber->lock);
- list_del(&sub->subscrp_list);
atomic_dec(&tn->subscription_count);
- spin_unlock_bh(&subscriber->lock);
kfree(sub);
tipc_subscrb_put(subscriber);
}
@@ -210,11 +208,8 @@ static void tipc_subscrb_subscrp_delete(struct
tipc_subscriber *subscriber,
continue;
tipc_nametbl_unsubscribe(sub);
- tipc_subscrp_get(sub);
- spin_unlock_bh(&subscriber->lock);
+ list_del(&sub->subscrp_list);
tipc_subscrp_delete(sub);
- tipc_subscrp_put(sub);
- spin_lock_bh(&subscriber->lock);
if (s)
break;
--
2.1.4
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