From: Willy Tarreau <w@1wt.eu>
Date: Tue, 16 Oct 2018 14:11:56 +0000 (+0200)
Subject: BUG/MEDIUM: threads: fix thread_release() at the end of the rendez-vous point
X-Git-Tag: v1.9-dev4~31
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a9c0252b2e8ff7bb728b84d977ac6e9581ea12f8;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: threads: fix thread_release() at the end of the rendez-vous point

There is a bug in this function used to release other threads. It leaves
the current thread marked as harmless. If after this another thread does
a thread_isolate(), but before the first one reaches poll(), the second
thread will believe it's alone while it's not.

This must be backported to 1.8 since the rendez-vous point was merged
into 1.8.14.
---

diff --git a/src/hathreads.c b/src/hathreads.c
index 2ee31de696..075866a609 100644
--- a/src/hathreads.c
+++ b/src/hathreads.c
@@ -88,12 +88,8 @@ void thread_isolate()
  */
 void thread_release()
 {
-	while (1) {
-		HA_ATOMIC_AND(&threads_want_rdv_mask, ~tid_bit);
-		if (!(threads_want_rdv_mask & all_threads_mask))
-			break;
-		thread_harmless_till_end();
-	}
+	HA_ATOMIC_AND(&threads_want_rdv_mask, ~tid_bit);
+	thread_harmless_end();
 }
 
 __attribute__((constructor))