[TIPC]: Added subscription cancellation capability

This patch allows a TIPC application to cancel an existing topology service subscription by re-requesting the subscription with the TIPC_SUB_CANCEL filter bit set. (All other bits of the cancel request must match the original subscription request.) Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Per Liden <per.liden@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>

[TIPC]: Added subscription cancellation capability
This patch allows a TIPC application to cancel an existing topology service subscription by re-requesting the subscription with the TIPC_SUB_CANCEL filter bit set. (All other bits of the cancel request must match the original subscription request.) Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: Per Liden <per.liden@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Lijun Chen · David S. Miller
1 parent fc144deec6
Showing 2 changed files with 85 additions and 15 deletions Side-by-side Diff
include/linux/tipc.h
net/tipc/subscr.c
@@ -129,6 +129,7 @@
  
 #define TIPC_SUB_PORTS     	0x01  	/* filter for port availability */
 #define TIPC_SUB_SERVICE     	0x02  	/* filter for service availability */
+#define TIPC_SUB_CANCEL         0x04    /* cancel a subscription */
 #if 0
 /* The following filter options are not currently implemented */
 #define TIPC_SUB_NO_BIND_EVTS	0x04	/* filter out "publish" events */
@@ -155,7 +155,7 @@
 	    sub->seq.upper, found_lower, found_upper);
 	if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 		return;
-	if (!must && (sub->filter != TIPC_SUB_PORTS))
+	if (!must && !(sub->filter & TIPC_SUB_PORTS))
 		return;
 	subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
 }
@@ -176,6 +176,13 @@
 	if (subscriber == NULL)
 		return;
  
+	/* Validate timeout (in case subscription is being cancelled) */
+
+	if (sub->timeout == TIPC_WAIT_FOREVER) {
+		tipc_ref_unlock(subscriber_ref);
+		return;
+	}
+
 	/* Unlink subscription from name table */
  
 	tipc_nametbl_unsubscribe(sub);
@@ -199,6 +206,20 @@
 }
  
 /**
+ * subscr_del - delete a subscription within a subscription list
+ *
+ * Called with subscriber locked.
+ */
+
+static void subscr_del(struct subscription *sub)
+{
+	tipc_nametbl_unsubscribe(sub);
+	list_del(&sub->subscription_list);
+	kfree(sub);
+	atomic_dec(&topsrv.subscription_count);
+}
+
+/**
  * subscr_terminate - terminate communication with a subscriber
  * 
  * Called with subscriber locked.  Routine must temporarily release this lock
  
@@ -227,12 +248,9 @@
 			k_cancel_timer(&sub->timer);
 			k_term_timer(&sub->timer);
 		}
-		tipc_nametbl_unsubscribe(sub);
-		list_del(&sub->subscription_list);
-		dbg("Term: Removed sub %u,%u,%u from subscriber %x list\n",
+		dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
 		    sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
-		kfree(sub);
-		atomic_dec(&topsrv.subscription_count);
+		subscr_del(sub);
 	}
  
 	/* Sever connection to subscriber */
@@ -253,6 +271,49 @@
 }
  
 /**
+ * subscr_cancel - handle subscription cancellation request
+ *
+ * Called with subscriber locked.  Routine must temporarily release this lock
+ * to enable the subscription timeout routine to finish without deadlocking;
+ * the lock is then reclaimed to allow caller to release it upon return.
+ *
+ * Note that fields of 's' use subscriber's endianness!
+ */
+
+static void subscr_cancel(struct tipc_subscr *s,
+			  struct subscriber *subscriber)
+{
+	struct subscription *sub;
+	struct subscription *sub_temp;
+	int found = 0;
+
+	/* Find first matching subscription, exit if not found */
+
+	list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
+				 subscription_list) {
+		if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found)
+		return;
+
+	/* Cancel subscription timer (if used), then delete subscription */
+
+	if (sub->timeout != TIPC_WAIT_FOREVER) {
+		sub->timeout = TIPC_WAIT_FOREVER;
+		spin_unlock_bh(subscriber->lock);
+		k_cancel_timer(&sub->timer);
+		k_term_timer(&sub->timer);
+		spin_lock_bh(subscriber->lock);
+	}
+	dbg("Cancel: removing sub %u,%u,%u from subscriber %x list\n",
+	    sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
+	subscr_del(sub);
+}
+
+/**
  * subscr_subscribe - create subscription for subscriber
  * 
  * Called with subscriber locked
@@ -263,6 +324,21 @@
 {
 	struct subscription *sub;
  
+	/* Determine/update subscriber's endianness */
+
+	if (s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE))
+		subscriber->swap = 0;
+	else
+		subscriber->swap = 1;
+
+	/* Detect & process a subscription cancellation request */
+
+	if (s->filter & htohl(TIPC_SUB_CANCEL, subscriber->swap)) {
+		s->filter &= ~htohl(TIPC_SUB_CANCEL, subscriber->swap);
+		subscr_cancel(s, subscriber);
+		return;
+	}
+
 	/* Refuse subscription if global limit exceeded */
  
 	if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
@@ -281,13 +357,6 @@
 		return;
 	}
  
-	/* Determine/update subscriber's endianness */
-
-	if ((s->filter == TIPC_SUB_PORTS) || (s->filter == TIPC_SUB_SERVICE))
-		subscriber->swap = 0;
-	else
-		subscriber->swap = 1;
-
 	/* Initialize subscription object */
  
 	memset(sub, 0, sizeof(*sub));
@@ -296,8 +365,8 @@
 	sub->seq.upper = htohl(s->seq.upper, subscriber->swap);
 	sub->timeout = htohl(s->timeout, subscriber->swap);
 	sub->filter = htohl(s->filter, subscriber->swap);
-	if ((((sub->filter != TIPC_SUB_PORTS) 
-	      && (sub->filter != TIPC_SUB_SERVICE)))
+	if ((!(sub->filter & TIPC_SUB_PORTS)
+	     == !(sub->filter & TIPC_SUB_SERVICE))
 	    || (sub->seq.lower > sub->seq.upper)) {
 		warn("Subscription rejected, illegal request\n");
 		kfree(sub);
...	...	@@ -129,6 +129,7 @@
129	129
130	130	#define TIPC_SUB_PORTS 0x01 /* filter for port availability */
131	131	#define TIPC_SUB_SERVICE 0x02 /* filter for service availability */
	132	+#define TIPC_SUB_CANCEL 0x04 /* cancel a subscription */
132	133	#if 0
133	134	/* The following filter options are not currently implemented */
134	135	#define TIPC_SUB_NO_BIND_EVTS 0x04 /* filter out "publish" events */
...	...	@@ -155,7 +155,7 @@
155	155	sub->seq.upper, found_lower, found_upper);
156	156	if (!tipc_subscr_overlap(sub, found_lower, found_upper))
157	157	return;
158		- if (!must && (sub->filter != TIPC_SUB_PORTS))
	158	+ if (!must && !(sub->filter & TIPC_SUB_PORTS))
159	159	return;
160	160	subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
161	161	}
...	...	@@ -176,6 +176,13 @@
176	176	if (subscriber == NULL)
177	177	return;
178	178
	179	+ /* Validate timeout (in case subscription is being cancelled) */
	180	+
	181	+ if (sub->timeout == TIPC_WAIT_FOREVER) {
	182	+ tipc_ref_unlock(subscriber_ref);
	183	+ return;
	184	+ }
	185	+
179	186	/* Unlink subscription from name table */
180	187
181	188	tipc_nametbl_unsubscribe(sub);
...	...	@@ -199,6 +206,20 @@
199	206	}
200	207
201	208	/**
	209	+ * subscr_del - delete a subscription within a subscription list
	210	+ *
	211	+ * Called with subscriber locked.
	212	+ */
	213	+
	214	+static void subscr_del(struct subscription *sub)
	215	+{
	216	+ tipc_nametbl_unsubscribe(sub);
	217	+ list_del(&sub->subscription_list);
	218	+ kfree(sub);
	219	+ atomic_dec(&topsrv.subscription_count);
	220	+}
	221	+
	222	+/**
202	223	* subscr_terminate - terminate communication with a subscriber
203	224	*
204	225	* Called with subscriber locked. Routine must temporarily release this lock
205	226
...	...	@@ -227,12 +248,9 @@
227	248	k_cancel_timer(&sub->timer);
228	249	k_term_timer(&sub->timer);
229	250	}
230		- tipc_nametbl_unsubscribe(sub);
231		- list_del(&sub->subscription_list);
232		- dbg("Term: Removed sub %u,%u,%u from subscriber %x list\n",
	251	+ dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
233	252	sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
234		- kfree(sub);
235		- atomic_dec(&topsrv.subscription_count);
	253	+ subscr_del(sub);
236	254	}
237	255
238	256	/* Sever connection to subscriber */
...	...	@@ -253,6 +271,49 @@
253	271	}
254	272
255	273	/**
	274	+ * subscr_cancel - handle subscription cancellation request
	275	+ *
	276	+ * Called with subscriber locked. Routine must temporarily release this lock
	277	+ * to enable the subscription timeout routine to finish without deadlocking;
	278	+ * the lock is then reclaimed to allow caller to release it upon return.
	279	+ *
	280	+ * Note that fields of 's' use subscriber's endianness!
	281	+ */
	282	+
	283	+static void subscr_cancel(struct tipc_subscr *s,
	284	+ struct subscriber *subscriber)
	285	+{
	286	+ struct subscription *sub;
	287	+ struct subscription *sub_temp;
	288	+ int found = 0;
	289	+
	290	+ /* Find first matching subscription, exit if not found */
	291	+
	292	+ list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
	293	+ subscription_list) {
	294	+ if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
	295	+ found = 1;
	296	+ break;
	297	+ }
	298	+ }
	299	+ if (!found)
	300	+ return;
	301	+
	302	+ /* Cancel subscription timer (if used), then delete subscription */
	303	+
	304	+ if (sub->timeout != TIPC_WAIT_FOREVER) {
	305	+ sub->timeout = TIPC_WAIT_FOREVER;
	306	+ spin_unlock_bh(subscriber->lock);
	307	+ k_cancel_timer(&sub->timer);
	308	+ k_term_timer(&sub->timer);
	309	+ spin_lock_bh(subscriber->lock);
	310	+ }
	311	+ dbg("Cancel: removing sub %u,%u,%u from subscriber %x list\n",
	312	+ sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
	313	+ subscr_del(sub);
	314	+}
	315	+
	316	+/**
256	317	* subscr_subscribe - create subscription for subscriber
257	318	*
258	319	* Called with subscriber locked
...	...	@@ -263,6 +324,21 @@
263	324	{
264	325	struct subscription *sub;
265	326
	327	+ /* Determine/update subscriber's endianness */
	328	+
	329	+ if (s->filter & (TIPC_SUB_PORTS \| TIPC_SUB_SERVICE))
	330	+ subscriber->swap = 0;
	331	+ else
	332	+ subscriber->swap = 1;
	333	+
	334	+ /* Detect & process a subscription cancellation request */
	335	+
	336	+ if (s->filter & htohl(TIPC_SUB_CANCEL, subscriber->swap)) {
	337	+ s->filter &= ~htohl(TIPC_SUB_CANCEL, subscriber->swap);
	338	+ subscr_cancel(s, subscriber);
	339	+ return;
	340	+ }
	341	+
266	342	/* Refuse subscription if global limit exceeded */
267	343
268	344	if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
...	...	@@ -281,13 +357,6 @@
281	357	return;
282	358	}
283	359
284		- /* Determine/update subscriber's endianness */
285		-
286		- if ((s->filter == TIPC_SUB_PORTS) \|\| (s->filter == TIPC_SUB_SERVICE))
287		- subscriber->swap = 0;
288		- else
289		- subscriber->swap = 1;
290		-
291	360	/* Initialize subscription object */
292	361
293	362	memset(sub, 0, sizeof(*sub));
...	...	@@ -296,8 +365,8 @@
296	365	sub->seq.upper = htohl(s->seq.upper, subscriber->swap);
297	366	sub->timeout = htohl(s->timeout, subscriber->swap);
298	367	sub->filter = htohl(s->filter, subscriber->swap);
299		- if ((((sub->filter != TIPC_SUB_PORTS)
300		- && (sub->filter != TIPC_SUB_SERVICE)))
	368	+ if ((!(sub->filter & TIPC_SUB_PORTS)
	369	+ == !(sub->filter & TIPC_SUB_SERVICE))
301	370	\|\| (sub->seq.lower > sub->seq.upper)) {
302	371	warn("Subscription rejected, illegal request\n");
303	372	kfree(sub);