bk commit into 5.0 tree (msvensson:1.2039) BUG#16333

[msvensson]

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ChangeSet
  1.2039 06/02/14 11:34:46 msvensson@neptunus.(none) +1 -0
  Bug#16333 Assertion failure in lock.cc in the sysbench test
   - Set the value of mp->thread before mp->count to avoid race condition.

  mysys/thr_mutex.c
    1.28 06/02/14 11:34:30 msvensson@neptunus.(none) +5 -4
    Set mp->thread before mp->count is changed. 
    Since mp->count is used in the macros 'safe_mutex_assert_not_owner' and 
    'safe_mutex_assert_owner' as an inidicator wheter to look at the mp->thread
    variable or not. This means that when mp->count is changed, the mp->thread
    should akready be set to the owning thread.
    Also set mp->thread to 0 when unlocking the mutex.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	msvensson
# Host:	neptunus.(none)
# Root:	/home/msvensson/mysql/bug16333/my50-bug16333

--- 1.27/mysys/thr_mutex.c	2005-10-11 23:58:17 +02:00
+++ 1.28/mysys/thr_mutex.c	2006-02-14 11:34:30 +01:00
@@ -103,7 +103,7 @@
     fflush(stderr);
     abort();
   }
-    
+
   pthread_mutex_lock(&mp->global);
   if (mp->count > 0 && pthread_equal(pthread_self(),mp->thread))
   {
@@ -121,6 +121,7 @@
     fflush(stderr);
     abort();
   }
+  mp->thread= pthread_self();
   if (mp->count++)
   {
     fprintf(stderr,"safe_mutex: Error in thread libray: Got mutex at %s, \
@@ -128,7 +129,6 @@
     fflush(stderr);
     abort();
   }
-  mp->thread=pthread_self();
   mp->file= file;
   mp->line=line;
   pthread_mutex_unlock(&mp->global);
@@ -154,6 +154,7 @@
     fflush(stderr);
     abort();
   }
+  mp->thread= 0;
   mp->count--;
 #ifdef __WIN__
   pthread_mutex_unlock(&mp->mutex);
@@ -207,6 +208,7 @@
     fflush(stderr);
     abort();
   }
+  mp->thread=pthread_self();
   if (mp->count++)
   {
     fprintf(stderr,
@@ -215,7 +217,6 @@
     fflush(stderr);
     abort();
   }
-  mp->thread=pthread_self();
   mp->file= file;
   mp->line=line;
   pthread_mutex_unlock(&mp->global);
@@ -245,6 +246,7 @@
   }
 #endif
   pthread_mutex_lock(&mp->global);
+  mp->thread=pthread_self();
   if (mp->count++)
   {
     fprintf(stderr,
@@ -253,7 +255,6 @@
     fflush(stderr);
     abort();
   }
-  mp->thread=pthread_self();
   mp->file= file;
   mp->line=line;
   pthread_mutex_unlock(&mp->global);