[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>
diff --git a/include/linux/tipc.h b/include/linux/tipc.h
index 243a15f..bea4694 100644
--- a/include/linux/tipc.h
+++ b/include/linux/tipc.h
@@ -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 */
diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index c51600b..7a918f1 100644
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -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);