From f8338151a31310fdbe55382c1ab8273c8413b0ca Mon Sep 17 00:00:00 2001
From: Olivier Houchard <ohouchard@haproxy.com>
Date: Tue, 14 May 2019 17:50:32 +0200
Subject: [PATCH] MINOR: h2: Use BUG_ON() to enforce rules in
 subscribe/unsubscribe.

It is not legal to subscribe if we're already subscribed, or to unsubscribe
if we did not subscribe, so instead of trying to handle those cases, just
assert that it's ok using the new BUG_ON() macro.
---
 src/mux_h2.c | 55 ++++++++++++++++++++++++----------------------------
 1 file changed, 25 insertions(+), 30 deletions(-)

diff --git a/src/mux_h2.c b/src/mux_h2.c
index 73d32a926..90c6a440c 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -5199,24 +5199,22 @@ static int h2_subscribe(struct conn_stream *cs, int event_type, void *param)
 
 	if (event_type & SUB_RETRY_RECV) {
 		sw = param;
-		if (!(sw->events & SUB_RETRY_RECV)) {
-			sw->events |= SUB_RETRY_RECV;
-			h2s->recv_wait = sw;
-		}
+		BUG_ON(h2s->recv_wait != NULL || (sw->events & SUB_RETRY_RECV));
+		sw->events |= SUB_RETRY_RECV;
+		h2s->recv_wait = sw;
 		event_type &= ~SUB_RETRY_RECV;
 	}
 	if (event_type & SUB_RETRY_SEND) {
 		sw = param;
-		if (!(sw->events & SUB_RETRY_SEND)) {
-			sw->events |= SUB_RETRY_SEND;
-			h2s->send_wait = sw;
-			if (!(h2s->flags & H2_SF_BLK_SFCTL) &&
-			    !LIST_ADDED(&h2s->list)) {
-				if (h2s->flags & H2_SF_BLK_MFCTL)
-					LIST_ADDQ(&h2c->fctl_list, &h2s->list);
-				else
-					LIST_ADDQ(&h2c->send_list, &h2s->list);
-			}
+		BUG_ON(h2s->send_wait != NULL || (sw->events & SUB_RETRY_SEND));
+		sw->events |= SUB_RETRY_SEND;
+		h2s->send_wait = sw;
+		if (!(h2s->flags & H2_SF_BLK_SFCTL) &&
+		    !LIST_ADDED(&h2s->list)) {
+			if (h2s->flags & H2_SF_BLK_MFCTL)
+				LIST_ADDQ(&h2c->fctl_list, &h2s->list);
+			else
+				LIST_ADDQ(&h2c->send_list, &h2s->list);
 		}
 		event_type &= ~SUB_RETRY_SEND;
 	}
@@ -5237,26 +5235,23 @@ static int h2_unsubscribe(struct conn_stream *cs, int event_type, void *param)
 
 	if (event_type & SUB_RETRY_RECV) {
 		sw = param;
-		if (h2s->recv_wait == sw) {
-			sw->events &= ~SUB_RETRY_RECV;
-			h2s->recv_wait = NULL;
-		}
+		BUG_ON(h2s->recv_wait != sw);
+		sw->events &= ~SUB_RETRY_RECV;
+		h2s->recv_wait = NULL;
 	}
 	if (event_type & SUB_RETRY_SEND) {
 		sw = param;
-		if (h2s->send_wait == sw) {
-			LIST_DEL(&h2s->list);
-			LIST_INIT(&h2s->list);
-			sw->events &= ~SUB_RETRY_SEND;
-			/* We were about to send, make sure it does not happen */
-			if (LIST_ADDED(&h2s->sending_list) &&
-			    h2s->send_wait != &h2s->wait_event) {
-				task_remove_from_tasklet_list((struct task *)h2s->send_wait->task);
-				LIST_DEL_INIT(&h2s->sending_list);
-			}
-			h2s->send_wait = NULL;
-
+		BUG_ON(h2s->send_wait != sw);
+		LIST_DEL(&h2s->list);
+		LIST_INIT(&h2s->list);
+		sw->events &= ~SUB_RETRY_SEND;
+		/* We were about to send, make sure it does not happen */
+		if (LIST_ADDED(&h2s->sending_list) &&
+		    h2s->send_wait != &h2s->wait_event) {
+			task_remove_from_tasklet_list((struct task *)h2s->send_wait->task);
+			LIST_DEL_INIT(&h2s->sending_list);
 		}
+		h2s->send_wait = NULL;
 	}
 	return 0;
 }