From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Wed, 10 Jun 2009 16:01:47 +0000 (-0400)
Subject: Fix deadlock in qsbr code
X-Git-Tag: v0.1~175
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=76f3022fdb3eaa23decfa5a61be4b351eb1a0114;p=urcu.git

Fix deadlock in qsbr code

Readers must go offline because they unregister.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 6ba0364..87c83d7 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -258,6 +258,11 @@ void rcu_register_thread(void)
 
 void rcu_unregister_thread(void)
 {
+	/*
+	 * We have to make the thread offline otherwise we end up dealocking
+	 * with a waiting writer.
+	 */
+	_rcu_thread_offline();
 	internal_urcu_lock();
 	rcu_remove_reader(pthread_self());
 	internal_urcu_unlock();