From: Christopher Faulet <cfaulet@haproxy.com>
Date: Wed, 14 Apr 2021 12:02:25 +0000 (+0200)
Subject: BUG/MEDIUM: threads: Ignore current thread to end its harmless period
X-Git-Tag: v2.4-dev17~108
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f63a18550073e821976606f9602c261976939ae9;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: threads: Ignore current thread to end its harmless period

A previous patch was pushed to fix a deadlock when an isolated thread ends
its harmless period (a9a9e9aac ["BUG/MEDIUM: thread: Fix a deadlock if an
isolated thread is marked as harmless"]). But, unfortunately, the fix is
incomplete. The same must be done in the outer loop, in
thread_harmless_end() function. The current thread must be ignored when
threads_want_rdv_mask mask is tested.

This patch must also be backported as far as 2.0.
---

diff --git a/include/haproxy/thread.h b/include/haproxy/thread.h
index 1a0813f64c..af909f1702 100644
--- a/include/haproxy/thread.h
+++ b/include/haproxy/thread.h
@@ -265,7 +265,7 @@ static inline void thread_harmless_end()
 {
 	while (1) {
 		HA_ATOMIC_AND(&threads_harmless_mask, ~tid_bit);
-		if (likely((threads_want_rdv_mask & all_threads_mask) == 0))
+		if (likely((threads_want_rdv_mask & ~tid_bit) == 0))
 			break;
 		thread_harmless_till_end();
 	}