[tipc-discussion] [net 3/5] tipc: adjust policy that sub->timer holds subscription kref

[Ying X. <yin...@wi...>]

To make it more conventional to hold subscription refcount in timer,
its policy is adjusted as follows:

Before sub->timer is started, subscription refcount is held; when
sub->timer is expired, subscription refcount will be decreased at the
end of the timer timeout function; when the timer is stopped, refcount
also needs to be decreased if the timer is still active.

Signed-off-by: Ying Xue <yin...@wi...>
---
 net/tipc/subscr.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index 111d33c6..ffd7b9d 100644
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -241,8 +241,10 @@ static void tipc_subscrp_delete(struct tipc_subscription *sub)
 {
 	u32 timeout = htohl(sub->evt.s.timeout, sub->swap);
 
-	if (timeout == TIPC_WAIT_FOREVER || del_timer(&sub->timer))
+	if (timeout != TIPC_WAIT_FOREVER && del_timer(&sub->timer))
 		tipc_subscrp_put(sub);
+
+	tipc_subscrp_put(sub);
 }
 
 static void tipc_subscrp_cancel(struct tipc_subscr *s,
@@ -303,16 +305,18 @@ static void tipc_subscrp_subscribe(struct net *net, struct tipc_subscr *s,
 	spin_lock_bh(&subscriber->lock);
 	list_add(&sub->subscrp_list, &subscriber->subscrp_list);
 
+	tipc_subscrb_get(subscriber);
 	sub->subscriber = subscriber;
+
 	tipc_nametbl_subscribe(sub);
-	tipc_subscrb_get(subscriber);
 	spin_unlock_bh(&subscriber->lock);
 
 	setup_timer(&sub->timer, tipc_subscrp_timeout, (unsigned long)sub);
 	timeout = htohl(sub->evt.s.timeout, swap);
 
-	if (timeout != TIPC_WAIT_FOREVER)
-		mod_timer(&sub->timer, jiffies + msecs_to_jiffies(timeout));
+	if ((timeout != TIPC_WAIT_FOREVER) &&
+	    !mod_timer(&sub->timer, jiffies + msecs_to_jiffies(timeout)))
+		tipc_subscrp_get(sub);
 }
 
 /* Handle one termination request for the subscriber */
-- 
2.7.4