From 7ee6a3ae5f805d84df6d5c78856b34fa9c2696a4 Mon Sep 17 00:00:00 2001
From: Vladislav Vaintroub <wlad@mariadb.com>
Date: Thu, 25 Jun 2020 09:58:42 +0200
Subject: MDEV-22950 followup

Deadlock in DbugParse, on Linux.

In 10.1, DBUG recursive mutex was improperly implemented.
CODE_STATE::locked counter was never updated.

Copy the code around LockMutex/UnlockMutex from 10.2
---
 dbug/dbug.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'dbug')

diff --git a/dbug/dbug.c b/dbug/dbug.c
index b0e1b0eaae6..007769c3c37 100644
--- a/dbug/dbug.c
+++ b/dbug/dbug.c
@@ -330,10 +330,13 @@ static void LockMutex(CODE_STATE *cs)
 {
   if (!cs->locked)
     pthread_mutex_lock(&THR_LOCK_dbug);
+  cs->locked++;
 }
 static void UnlockMutex(CODE_STATE *cs)
 {
-  if (!cs->locked)
+  --cs->locked;
+  assert(cs->locked >= 0);
+  if (cs->locked == 0)
     pthread_mutex_unlock(&THR_LOCK_dbug);
 }
 static void LockIfInitSettings(CODE_STATE *cs)
-- 
cgit v1.2.1