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Commit eb409460 authored by Lijun Chen's avatar Lijun Chen Committed by David S. Miller
Browse files

[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: default avatarAllan Stephens <allan.stephens@windriver.com>
Signed-off-by: default avatarPer Liden <per.liden@ericsson.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent fc144dee

include/linux/tipc.h

+1 −0
Original line number Diff line number Diff line
@@ -129,6 +129,7 @@ static inline unsigned int tipc_node(__u32 addr) 


#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 */

net/tipc/subscr.c

+84 −15
Original line number Diff line number Diff line
@@ -155,7 +155,7 @@ void tipc_subscr_report_overlap(struct subscription *sub, 
	    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 @@ static void subscr_timeout(struct subscription *sub) 
	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);
@@ -198,6 +205,20 @@ static void subscr_timeout(struct subscription *sub) 
	atomic_dec(&topsrv.subscription_count);

}



/**

 * 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

 *
@@ -227,12 +248,9 @@ static void subscr_terminate(struct subscriber *subscriber) 
			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 */
@@ -252,6 +270,49 @@ static void subscr_terminate(struct subscriber *subscriber) 
	kfree(subscriber);

}



/**

 * 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

 *
@@ -263,6 +324,21 @@ static void subscr_subscribe(struct tipc_subscr *s, 
{

	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 @@ static void subscr_subscribe(struct tipc_subscr *s, 
		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 @@ static void subscr_subscribe(struct tipc_subscr *s, 
	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);