1 files changed, 113 insertions, 86 deletions

diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index dde23f1e754..7c62791eb0c 100644
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -38,23 +38,22 @@
 #include "dbg.h"
 #include "subscr.h"
 #include "name_table.h"
+#include "port.h"
 #include "ref.h"
 
 /**
  * struct subscriber - TIPC network topology subscriber
- * @ref: object reference to subscriber object itself
- * @lock: pointer to spinlock controlling access to subscriber object
+ * @port_ref: object reference to server port connecting to subscriber
+ * @lock: pointer to spinlock controlling access to subscriber's server port
  * @subscriber_list: adjacent subscribers in top. server's list of subscribers
  * @subscription_list: list of subscription objects for this subscriber
- * @port_ref: object reference to port used to communicate with subscriber
  */
 
 struct subscriber {
-	u32 ref;
+	u32 port_ref;
 	spinlock_t *lock;
 	struct list_head subscriber_list;
 	struct list_head subscription_list;
-	u32 port_ref;
 };
 
 /**
@@ -91,6 +90,9 @@ static u32 htohl(u32 in, int swap)
 
 /**
  * subscr_send_event - send a message containing a tipc_event to the subscriber
+ *
+ * Note: Must not hold subscriber's server port lock, since tipc_send() will
+ *       try to take the lock if the message is rejected and returned!
  */
 
 static void subscr_send_event(struct subscription *sub,
@@ -110,7 +112,7 @@ static void subscr_send_event(struct subscription *sub,
 	sub->evt.found_upper = htohl(found_upper, sub->swap);
 	sub->evt.port.ref = htohl(port_ref, sub->swap);
 	sub->evt.port.node = htohl(node, sub->swap);
-	tipc_send(sub->owner->port_ref, 1, &msg_sect);
+	tipc_send(sub->server_ref, 1, &msg_sect);
 }
 
 /**
@@ -163,20 +165,18 @@ void tipc_subscr_report_overlap(struct subscription *sub,
 
 static void subscr_timeout(struct subscription *sub)
 {
-	struct subscriber *subscriber;
-	u32 subscriber_ref;
+	struct port *server_port;
 
-	/* Validate subscriber reference (in case subscriber is terminating) */
+	/* Validate server port reference (in case subscriber is terminating) */
 
-	subscriber_ref = sub->owner->ref;
-	subscriber = (struct subscriber *)tipc_ref_lock(subscriber_ref);
-	if (subscriber == NULL)
+	server_port = tipc_port_lock(sub->server_ref);
+	if (server_port == NULL)
 		return;
 
 	/* Validate timeout (in case subscription is being cancelled) */
 
 	if (sub->timeout == TIPC_WAIT_FOREVER) {
-		tipc_ref_unlock(subscriber_ref);
+		tipc_port_unlock(server_port);
 		return;
 	}
 
@@ -184,19 +184,21 @@ static void subscr_timeout(struct subscription *sub)
 
 	tipc_nametbl_unsubscribe(sub);
 
-	/* Notify subscriber of timeout, then unlink subscription */
+	/* Unlink subscription from subscriber */
 
-	subscr_send_event(sub,
-			  sub->evt.s.seq.lower,
-			  sub->evt.s.seq.upper,
-			  TIPC_SUBSCR_TIMEOUT,
-			  0,
-			  0);
 	list_del(&sub->subscription_list);
 
+	/* Release subscriber's server port */
+
+	tipc_port_unlock(server_port);
+
+	/* Notify subscriber of timeout */
+
+	subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
+			  TIPC_SUBSCR_TIMEOUT, 0, 0);
+
 	/* Now destroy subscription */
 
-	tipc_ref_unlock(subscriber_ref);
 	k_term_timer(&sub->timer);
 	kfree(sub);
 	atomic_dec(&topsrv.subscription_count);
@@ -205,7 +207,7 @@ static void subscr_timeout(struct subscription *sub)
 /**
  * subscr_del - delete a subscription within a subscription list
  *
- * Called with subscriber locked.
+ * Called with subscriber port locked.
  */
 
 static void subscr_del(struct subscription *sub)
@@ -219,7 +221,7 @@ static void subscr_del(struct subscription *sub)
 /**
  * subscr_terminate - terminate communication with a subscriber
  *
- * Called with subscriber locked.  Routine must temporarily release this lock
+ * Called with subscriber port locked.  Routine must temporarily release lock
  * to enable subscription timeout routine(s) to finish without deadlocking;
  * the lock is then reclaimed to allow caller to release it upon return.
  * (This should work even in the unlikely event some other thread creates
@@ -229,14 +231,21 @@ static void subscr_del(struct subscription *sub)
 
 static void subscr_terminate(struct subscriber *subscriber)
 {
+	u32 port_ref;
 	struct subscription *sub;
 	struct subscription *sub_temp;
 
 	/* Invalidate subscriber reference */
 
-	tipc_ref_discard(subscriber->ref);
+	port_ref = subscriber->port_ref;
+	subscriber->port_ref = 0;
 	spin_unlock_bh(subscriber->lock);
 
+	/* Sever connection to subscriber */
+
+	tipc_shutdown(port_ref);
+	tipc_deleteport(port_ref);
+
 	/* Destroy any existing subscriptions for subscriber */
 
 	list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
@@ -250,27 +259,25 @@ static void subscr_terminate(struct subscriber *subscriber)
 		subscr_del(sub);
 	}
 
-	/* Sever connection to subscriber */
-
-	tipc_shutdown(subscriber->port_ref);
-	tipc_deleteport(subscriber->port_ref);
-
 	/* Remove subscriber from topology server's subscriber list */
 
 	spin_lock_bh(&topsrv.lock);
 	list_del(&subscriber->subscriber_list);
 	spin_unlock_bh(&topsrv.lock);
 
-	/* Now destroy subscriber */
+	/* Reclaim subscriber lock */
 
 	spin_lock_bh(subscriber->lock);
+
+	/* Now destroy subscriber */
+
 	kfree(subscriber);
 }
 
 /**
  * subscr_cancel - handle subscription cancellation request
  *
- * Called with subscriber locked.  Routine must temporarily release this lock
+ * Called with subscriber port locked.  Routine must temporarily release lock
  * to enable the subscription timeout routine to finish without deadlocking;
  * the lock is then reclaimed to allow caller to release it upon return.
  *
@@ -313,11 +320,11 @@ static void subscr_cancel(struct tipc_subscr *s,
 /**
  * subscr_subscribe - create subscription for subscriber
  *
- * Called with subscriber locked
+ * Called with subscriber port locked.
  */
 
-static void subscr_subscribe(struct tipc_subscr *s,
-			     struct subscriber *subscriber)
+static struct subscription *subscr_subscribe(struct tipc_subscr *s,
+					     struct subscriber *subscriber)
 {
 	struct subscription *sub;
 	int swap;
@@ -331,7 +338,7 @@ static void subscr_subscribe(struct tipc_subscr *s,
 	if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 		s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 		subscr_cancel(s, subscriber);
-		return;
+		return NULL;
 	}
 
 	/* Refuse subscription if global limit exceeded */
@@ -340,16 +347,16 @@ static void subscr_subscribe(struct tipc_subscr *s,
 		warn("Subscription rejected, subscription limit reached (%u)\n",
 		     tipc_max_subscriptions);
 		subscr_terminate(subscriber);
-		return;
+		return NULL;
 	}
 
 	/* Allocate subscription object */
 
-	sub = kzalloc(sizeof(*sub), GFP_ATOMIC);
+	sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 	if (!sub) {
 		warn("Subscription rejected, no memory\n");
 		subscr_terminate(subscriber);
-		return;
+		return NULL;
 	}
 
 	/* Initialize subscription object */
@@ -365,40 +372,41 @@ static void subscr_subscribe(struct tipc_subscr *s,
 		warn("Subscription rejected, illegal request\n");
 		kfree(sub);
 		subscr_terminate(subscriber);
-		return;
+		return NULL;
 	}
 	sub->event_cb = subscr_send_event;
-	memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
-	INIT_LIST_HEAD(&sub->subscription_list);
 	INIT_LIST_HEAD(&sub->nameseq_list);
 	list_add(&sub->subscription_list, &subscriber->subscription_list);
+	sub->server_ref = subscriber->port_ref;
 	sub->swap = swap;
+	memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 	atomic_inc(&topsrv.subscription_count);
 	if (sub->timeout != TIPC_WAIT_FOREVER) {
 		k_init_timer(&sub->timer,
 			     (Handler)subscr_timeout, (unsigned long)sub);
 		k_start_timer(&sub->timer, sub->timeout);
 	}
-	sub->owner = subscriber;
-	tipc_nametbl_subscribe(sub);
+
+	return sub;
 }
 
 /**
  * subscr_conn_shutdown_event - handle termination request from subscriber
+ *
+ * Called with subscriber's server port unlocked.
  */
 
 static void subscr_conn_shutdown_event(void *usr_handle,
-				       u32 portref,
+				       u32 port_ref,
 				       struct sk_buff **buf,
 				       unsigned char const *data,
 				       unsigned int size,
 				       int reason)
 {
-	struct subscriber *subscriber;
+	struct subscriber *subscriber = usr_handle;
 	spinlock_t *subscriber_lock;
 
-	subscriber = tipc_ref_lock((u32)(unsigned long)usr_handle);
-	if (subscriber == NULL)
+	if (tipc_port_lock(port_ref) == NULL)
 		return;
 
 	subscriber_lock = subscriber->lock;
@@ -408,6 +416,8 @@ static void subscr_conn_shutdown_event(void *usr_handle,
 
 /**
  * subscr_conn_msg_event - handle new subscription request from subscriber
+ *
+ * Called with subscriber's server port unlocked.
  */
 
 static void subscr_conn_msg_event(void *usr_handle,
@@ -416,20 +426,46 @@ static void subscr_conn_msg_event(void *usr_handle,
 				  const unchar *data,
 				  u32 size)
 {
-	struct subscriber *subscriber;
+	struct subscriber *subscriber = usr_handle;
 	spinlock_t *subscriber_lock;
+	struct subscription *sub;
+
+	/*
+	 * Lock subscriber's server port (& make a local copy of lock pointer,
+	 * in case subscriber is deleted while processing subscription request)
+	 */
 
-	subscriber = tipc_ref_lock((u32)(unsigned long)usr_handle);
-	if (subscriber == NULL)
+	if (tipc_port_lock(port_ref) == NULL)
 		return;
 
 	subscriber_lock = subscriber->lock;
-	if (size != sizeof(struct tipc_subscr))
-		subscr_terminate(subscriber);
-	else
-		subscr_subscribe((struct tipc_subscr *)data, subscriber);
 
-	spin_unlock_bh(subscriber_lock);
+	if (size != sizeof(struct tipc_subscr)) {
+		subscr_terminate(subscriber);
+		spin_unlock_bh(subscriber_lock);
+	} else {
+		sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
+		spin_unlock_bh(subscriber_lock);
+		if (sub != NULL) {
+
+			/*
+			 * We must release the server port lock before adding a
+			 * subscription to the name table since TIPC needs to be
+			 * able to (re)acquire the port lock if an event message
+			 * issued by the subscription process is rejected and
+			 * returned.  The subscription cannot be deleted while
+			 * it is being added to the name table because:
+			 * a) the single-threading of the native API port code
+			 *    ensures the subscription cannot be cancelled and
+			 *    the subscriber connection cannot be broken, and
+			 * b) the name table lock ensures the subscription
+			 *    timeout code cannot delete the subscription,
+			 * so the subscription object is still protected.
+			 */
+
+			tipc_nametbl_subscribe(sub);
+		}
+	}
 }
 
 /**
@@ -445,16 +481,10 @@ static void subscr_named_msg_event(void *usr_handle,
 				   struct tipc_portid const *orig,
 				   struct tipc_name_seq const *dest)
 {
-	struct subscriber *subscriber;
-	struct iovec msg_sect = {NULL, 0};
-	spinlock_t *subscriber_lock;
+	static struct iovec msg_sect = {NULL, 0};
 
-	dbg("subscr_named_msg_event: orig = %x own = %x,\n",
-	    orig->node, tipc_own_addr);
-	if (size && (size != sizeof(struct tipc_subscr))) {
-		warn("Subscriber rejected, invalid subscription size\n");
-		return;
-	}
+	struct subscriber *subscriber;
+	u32 server_port_ref;
 
 	/* Create subscriber object */
 
@@ -465,18 +495,11 @@ static void subscr_named_msg_event(void *usr_handle,
 	}
 	INIT_LIST_HEAD(&subscriber->subscription_list);
 	INIT_LIST_HEAD(&subscriber->subscriber_list);
-	subscriber->ref = tipc_ref_acquire(subscriber, &subscriber->lock);
-	if (subscriber->ref == 0) {
-		warn("Subscriber rejected, reference table exhausted\n");
-		kfree(subscriber);
-		return;
-	}
-	spin_unlock_bh(subscriber->lock);
 
-	/* Establish a connection to subscriber */
+	/* Create server port & establish connection to subscriber */
 
 	tipc_createport(topsrv.user_ref,
-			(void *)(unsigned long)subscriber->ref,
+			subscriber,
 			importance,
 			NULL,
 			NULL,
@@ -488,32 +511,36 @@ static void subscr_named_msg_event(void *usr_handle,
 			&subscriber->port_ref);
 	if (subscriber->port_ref == 0) {
 		warn("Subscriber rejected, unable to create port\n");
-		tipc_ref_discard(subscriber->ref);
 		kfree(subscriber);
 		return;
 	}
 	tipc_connect2port(subscriber->port_ref, orig);
 
+	/* Lock server port (& save lock address for future use) */
+
+	subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;
 
 	/* Add subscriber to topology server's subscriber list */
 
-	tipc_ref_lock(subscriber->ref);
 	spin_lock_bh(&topsrv.lock);
 	list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
 	spin_unlock_bh(&topsrv.lock);
 
-	/*
-	 * Subscribe now if message contains a subscription,
-	 * otherwise send an empty response to complete connection handshaking
-	 */
+	/* Unlock server port */
 
-	subscriber_lock = subscriber->lock;
-	if (size)
-		subscr_subscribe((struct tipc_subscr *)data, subscriber);
-	else
-		tipc_send(subscriber->port_ref, 1, &msg_sect);
+	server_port_ref = subscriber->port_ref;
+	spin_unlock_bh(subscriber->lock);
 
-	spin_unlock_bh(subscriber_lock);
+	/* Send an ACK- to complete connection handshaking */
+
+	tipc_send(server_port_ref, 1, &msg_sect);
+
+	/* Handle optional subscription request */
+
+	if (size != 0) {
+		subscr_conn_msg_event(subscriber, server_port_ref,
+				      buf, data, size);
+	}
 }
 
 int tipc_subscr_start(void)
@@ -572,8 +599,8 @@ void tipc_subscr_stop(void)
 		list_for_each_entry_safe(subscriber, subscriber_temp,
 					 &topsrv.subscriber_list,
 					 subscriber_list) {
-			tipc_ref_lock(subscriber->ref);
 			subscriber_lock = subscriber->lock;
+			spin_lock_bh(subscriber_lock);
 			subscr_terminate(subscriber);
 			spin_unlock_bh(subscriber_lock);
 		}