From a13683f292b2ce697f71fa3788a9335ebcb32676 Mon Sep 17 00:00:00 2001 From: Ying Xue Date: Mon, 4 May 2015 10:36:47 +0800 Subject: [PATCH] tipc: adjust locking policy of subscription Currently subscriber's lock protects not only subscriber's subscription list but also all subscriptions linked into the list. However, as all members of subscription are never changed after they are initialized, it's unnecessary for subscription to be protected under subscriber's lock. If the lock is used to only protect subscriber's subscription list, the adjustment not only makes the locking policy simpler, but also helps to avoid a deadlock which may happen once creating a subscription is failed. Signed-off-by: Ying Xue Reviewed-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/subscr.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c index 9b24c9c7e05a..350cca33ee0a 100644 --- a/net/tipc/subscr.c +++ b/net/tipc/subscr.c @@ -201,6 +201,7 @@ static void tipc_subscrp_cancel(struct tipc_subscr *s, { struct tipc_subscription *sub, *temp; + spin_lock_bh(&subscriber->lock); /* Find first matching subscription, exit if not found */ list_for_each_entry_safe(sub, temp, &subscriber->subscrp_list, subscrp_list) { @@ -212,6 +213,7 @@ static void tipc_subscrp_cancel(struct tipc_subscr *s, break; } } + spin_unlock_bh(&subscriber->lock); } static int tipc_subscrp_create(struct net *net, struct tipc_subscr *s, @@ -260,7 +262,9 @@ static int tipc_subscrp_create(struct net *net, struct tipc_subscr *s, kfree(sub); return -EINVAL; } + spin_lock_bh(&subscriber->lock); list_add(&sub->subscrp_list, &subscriber->subscrp_list); + spin_unlock_bh(&subscriber->lock); sub->subscriber = subscriber; sub->swap = swap; memcpy(&sub->evt.s, s, sizeof(*s)); @@ -289,13 +293,11 @@ static void tipc_subscrb_rcv_cb(struct net *net, int conid, struct tipc_subscription *sub = NULL; struct tipc_net *tn = net_generic(net, tipc_net_id); - spin_lock_bh(&subscriber->lock); tipc_subscrp_create(net, (struct tipc_subscr *)buf, subscriber, &sub); if (sub) tipc_nametbl_subscribe(sub); else tipc_conn_terminate(tn->topsrv, subscriber->conid); - spin_unlock_bh(&subscriber->lock); } /* Handle one request to establish a new subscriber */ -- 2.20.1