Commit 7efea60d authored by Ying Xue's avatar Ying Xue Committed by David S. Miller
Browse files

tipc: adjust the policy of holding subscription kref 



When a new subscription object is inserted into name_seq->subscriptions
list, it's under name_seq->lock protection; when a subscription is
deleted from the list, it's also under the same lock protection;
similarly, when accessing a subscription by going through subscriptions
list, the entire process is also protected by the name_seq->lock.

Therefore, if subscription refcount is increased before it's inserted
into subscriptions list, and its refcount is decreased after it's
deleted from the list, it will be unnecessary to hold refcount at all
before accessing subscription object which is obtained by going through
subscriptions list under name_seq->lock protection.

Signed-off-by: default avatarYing Xue <ying.xue@windriver.com>
Reviewed-by: default avatarJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 139bb36f

net/tipc/name_table.c

+2 −0
Original line number Diff line number Diff line
@@ -416,6 +416,7 @@ static void tipc_nameseq_subscribe(struct name_seq *nseq, 


	tipc_subscrp_convert_seq(&s->evt.s.seq, s->swap, &ns);



	tipc_subscrp_get(s);

	list_add(&s->nameseq_list, &nseq->subscriptions);



	if (!sseq)
@@ -787,6 +788,7 @@ void tipc_nametbl_unsubscribe(struct tipc_subscription *s) 
	if (seq != NULL) {

		spin_lock_bh(&seq->lock);

		list_del_init(&s->nameseq_list);

		tipc_subscrp_put(s);

		if (!seq->first_free && list_empty(&seq->subscriptions)) {

			hlist_del_init_rcu(&seq->ns_list);

			kfree(seq->sseqs);

net/tipc/subscr.c

+2 −6
Original line number Diff line number Diff line
@@ -54,8 +54,6 @@ struct tipc_subscriber { 


static void tipc_subscrp_delete(struct tipc_subscription *sub);

static void tipc_subscrb_put(struct tipc_subscriber *subscriber);

static void tipc_subscrp_put(struct tipc_subscription *subscription);

static void tipc_subscrp_get(struct tipc_subscription *subscription);



/**

 * htohl - convert value to endianness used by destination
@@ -125,7 +123,6 @@ void tipc_subscrp_report_overlap(struct tipc_subscription *sub, u32 found_lower, 
{

	struct tipc_name_seq seq;



	tipc_subscrp_get(sub);

	tipc_subscrp_convert_seq(&sub->evt.s.seq, sub->swap, &seq);

	if (!tipc_subscrp_check_overlap(&seq, found_lower, found_upper))

		return;
@@ -135,7 +132,6 @@ void tipc_subscrp_report_overlap(struct tipc_subscription *sub, u32 found_lower, 


	tipc_subscrp_send_event(sub, found_lower, found_upper, event, port_ref,

				node);

	tipc_subscrp_put(sub);

}



static void tipc_subscrp_timeout(unsigned long data)
@@ -183,12 +179,12 @@ static void tipc_subscrp_kref_release(struct kref *kref) 
	tipc_subscrb_put(subscriber);

}



static void tipc_subscrp_put(struct tipc_subscription *subscription)

void tipc_subscrp_put(struct tipc_subscription *subscription)

{

	kref_put(&subscription->kref, tipc_subscrp_kref_release);

}



static void tipc_subscrp_get(struct tipc_subscription *subscription)

void tipc_subscrp_get(struct tipc_subscription *subscription)

{

	kref_get(&subscription->kref);

}

net/tipc/subscr.h

+3 −0
Original line number Diff line number Diff line
@@ -78,4 +78,7 @@ u32 tipc_subscrp_convert_seq_type(u32 type, int swap); 
int tipc_topsrv_start(struct net *net);

void tipc_topsrv_stop(struct net *net);



void tipc_subscrp_put(struct tipc_subscription *subscription);

void tipc_subscrp_get(struct tipc_subscription *subscription);



#endif

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