Merge mysql.com:/home/bk/MERGE/mysql-5.0-merge

into  mysql.com:/home/bk/MERGE/mysql-5.1-merge

include/my_pthread.h

@@ -31,8 +31,26 @@ extern "C" {
 #define EXTERNC
 #endif /* __cplusplus */ 
 
-#if defined(__WIN__)
+/*
+  BUG#24507: Race conditions inside current NPTL pthread_exit() implementation.
+  
+  If macro NPTL_PTHREAD_EXIT_HACK is defined then a hack described in the bug
+  report will be implemented inside my_thread_global_init() in my_thr_init.c.
+   
+  This amounts to spawning a dummy thread which does nothing but executes 
+  pthread_exit(0). 
+  
+  This bug is fixed in version 2.5 of glibc library.
   
+  TODO: Remove this code when fixed versions of glibc6 are in common use. 
+ */
+
+#if defined(TARGET_OS_LINUX) && defined(HAVE_NPTL) && \
+    defined(__GLIBC__) && ( __GLIBC__ < 2 || __GLIBC__ == 2 && __GLIBC_MINOR__ < 5 )
+#define NPTL_PTHREAD_EXIT_BUG	1
+#endif 
+
+#if defined(__WIN__)
 typedef CRITICAL_SECTION pthread_mutex_t;
 typedef HANDLE		 pthread_t;
 typedef struct thread_attr {

mysys/my_thr_init.c

@@ -47,6 +47,23 @@ pthread_mutexattr_t my_fast_mutexattr;
 pthread_mutexattr_t my_errorcheck_mutexattr;
 #endif
 
+#ifdef NPTL_PTHREAD_EXIT_BUG /* see my_pthread.h */
+
+/*
+ Dummy thread spawned in my_thread_global_init() below to avoid
+ race conditions in NPTL pthread_exit code.
+*/
+
+static
+pthread_handler_t nptl_pthread_exit_hack_handler(void *arg)
+{
+  /* Do nothing! */
+  pthread_exit(0);
+  return 0;
+}
+
+#endif
+
 /*
   initialize thread environment
 
@@ -66,6 +83,28 @@ my_bool my_thread_global_init(void)
     return 1;
   }
   
+#ifdef NPTL_PTHREAD_EXIT_BUG
+
+/*
+  BUG#24507: Race conditions inside current NPTL pthread_exit() implementation.
+
+  To avoid a possible segmentation fault during concurrent executions of 
+  pthread_exit(), a dummy thread is spawned which initializes internal variables
+  of pthread lib. See bug description for thoroughfull explanation. 
+  
+  TODO: Remove this code when fixed versions of glibc6 are in common use. 
+*/
+
+  pthread_t       dummy_thread;
+  pthread_attr_t  dummy_thread_attr;
+
+  pthread_attr_init(&dummy_thread_attr);
+  pthread_attr_setdetachstate(&dummy_thread_attr,PTHREAD_CREATE_DETACHED);
+
+  pthread_create(&dummy_thread,&dummy_thread_attr,nptl_pthread_exit_hack_handler,NULL);
+
+#endif
+
 #ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
   /*
     Set mutex type to "fast" a.k.a "adaptive"