shaper: fixed possible race during changing time range

1 files changed, 27 insertions, 15 deletions

diff --git a/accel-pppd/shaper/shaper.c b/accel-pppd/shaper/shaper.c
index 09f03f3..b89ad36 100644
--- a/accel-pppd/shaper/shaper.c
+++ b/accel-pppd/shaper/shaper.c
@@ -57,8 +57,7 @@ static pthread_rwlock_t shaper_lock = PTHREAD_RWLOCK_INITIALIZER;
 static LIST_HEAD(shaper_list);
 
 struct time_range_pd_t;
-struct shaper_pd_t
-{
+struct shaper_pd_t {
 	struct list_head entry;
 	struct ap_session *ses;
 	struct ap_private pd;
@@ -68,10 +67,10 @@ struct shaper_pd_t
 	int up_speed;
 	struct list_head tr_list;
 	struct time_range_pd_t *cur_tr;
+	int refs;
 };
 
-struct time_range_pd_t
-{
+struct time_range_pd_t {
 	struct list_head entry;
 	int id;
 	int down_speed;
@@ -80,8 +79,7 @@ struct time_range_pd_t
 	int up_burst;
 };
 
-struct time_range_t
-{
+struct time_range_t {
 	struct list_head entry;
 	int id;
 	struct triton_timer_t begin;
@@ -123,6 +121,7 @@ static struct shaper_pd_t *find_pd(struct ap_session *ses, int create)
 		list_add_tail(&spd->pd.entry, &ses->pd_list);
 		spd->pd.key = &pd_key;
 		INIT_LIST_HEAD(&spd->tr_list);
+		spd->refs = 1;
 
 		pthread_rwlock_wrlock(&shaper_lock);
 		list_add_tail(&spd->entry, &shaper_list);
@@ -423,16 +422,20 @@ static void ev_ppp_finishing(struct ap_session *ses)
 	struct shaper_pd_t *pd = find_pd(ses, 0);
 
 	if (pd) {
-		clear_tr_pd(pd);
 		pthread_rwlock_wrlock(&shaper_lock);
 		list_del(&pd->entry);
 		pthread_rwlock_unlock(&shaper_lock);
+
 		list_del(&pd->pd.entry);
 
 		if (pd->down_speed || pd->up_speed)
 			remove_limiter(ses);
 
-		_free(pd);
+		if (--pd->refs == 0) {
+			clear_tr_pd(pd);
+			_free(pd);
+		} else
+			pd->ses = NULL;
 	}
 }
 
@@ -613,8 +616,8 @@ static void update_shaper_tr(struct shaper_pd_t *pd)
 {
 	struct time_range_pd_t *tr;
 
-	if (pd->ses->terminating)
-		return;
+	if (!pd->ses || pd->ses->terminating)
+		goto out;
 
 	list_for_each_entry(tr, &pd->tr_list, entry) {
 		if (tr->id != time_range_id)
@@ -624,11 +627,11 @@ static void update_shaper_tr(struct shaper_pd_t *pd)
 	}
 
 	if (pd->temp_down_speed || pd->temp_up_speed)
-		return;
+		goto out;
 
 	if (pd->down_speed || pd->up_speed) {
 		if (pd->cur_tr && pd->down_speed == pd->cur_tr->down_speed && pd->up_speed == pd->cur_tr->up_speed)
-			return;
+			goto out;
 		remove_limiter(pd->ses);
 	}
 	
@@ -639,9 +642,16 @@ static void update_shaper_tr(struct shaper_pd_t *pd)
 			if (conf_verbose)
 				log_ppp_info2("shaper: changed shaper %i/%i (Kbit)\n", pd->cur_tr->down_speed, pd->cur_tr->up_speed);
 		}
-	} else
+	} else {
 		if (conf_verbose)
-			log_ppp_info2("shaper: removed shaper\n");	
+			log_ppp_info2("shaper: removed shaper\n");
+	}
+
+out:
+	if (--pd->refs == 0) {
+		clear_tr_pd(pd);
+		_free(pd);
+	}
 }
 
 static void time_range_begin_timer(struct triton_timer_t *t)
@@ -654,8 +664,10 @@ static void time_range_begin_timer(struct triton_timer_t *t)
 	log_debug("shaper: time_range_begin_timer: id=%i\n", time_range_id);
 
 	pthread_rwlock_rdlock(&shaper_lock);
-	list_for_each_entry(pd, &shaper_list, entry)
+	list_for_each_entry(pd, &shaper_list, entry) {
+		pd->refs++;
 		triton_context_call(pd->ses->ctrl->ctx, (triton_event_func)update_shaper_tr, pd);
+	}
 	pthread_rwlock_unlock(&shaper_lock);
 }