From 5d7af856f769a77b398de64597458eca252ef43c Mon Sep 17 00:00:00 2001
From: "rafal@quant.(none)" <>
Date: Fri, 8 Dec 2006 11:41:12 +0100
Subject: [PATCH 1/2] BUG#24507 (rpl_log.test crash slave):

The problem was located to lie inside current NPTL pthread_exit()
implementation. Race conditions in this code can lead to segmentation
fault. Hovewer, this can happen only in a race between first thread
calling pthread_exit() and other threads.

Workaround implemented in this patch spawns a dummy thread, which
exits immediately, during thread lib initialization. This will exclude
segment violations when further threads exit.
---
 include/my_pthread.h | 20 ++++++++++++++++++++
 mysys/my_thr_init.c  | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/include/my_pthread.h b/include/my_pthread.h
index 3e4388413e0..8051d75c59e 100644
--- a/include/my_pthread.h
+++ b/include/my_pthread.h
@@ -31,6 +31,26 @@ extern "C" {
 #define EXTERNC
 #endif /* __cplusplus */ 
 
+/*
+  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__) || defined(OS2)
 
 #ifdef OS2
diff --git a/mysys/my_thr_init.c b/mysys/my_thr_init.c
index 4d23d01cd82..6663af986dd 100644
--- a/mysys/my_thr_init.c
+++ b/mysys/my_thr_init.c
@@ -44,6 +44,23 @@ 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
 
@@ -62,6 +79,28 @@ my_bool my_thread_global_init(void)
     fprintf(stderr,"Can't initialize threads: error %d\n",errno);
     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
   /*

From c82cd4a46eea3e44f948bf48c9175ef6883d5f95 Mon Sep 17 00:00:00 2001
From: "rafal@quant.(none)" <>
Date: Fri, 8 Dec 2006 19:23:12 +0100
Subject: [PATCH 2/2] Minor fix

---
 include/my_pthread.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/my_pthread.h b/include/my_pthread.h
index 8051d75c59e..24f3fd62b8e 100644
--- a/include/my_pthread.h
+++ b/include/my_pthread.h
@@ -45,7 +45,7 @@ extern "C" {
   TODO: Remove this code when fixed versions of glibc6 are in common use. 
  */
 
-#if defined(TARGET_OS_LINUX) && defined(HAVE_NPTL) &&
+#if defined(TARGET_OS_LINUX) && defined(HAVE_NPTL) && \
     defined(__GLIBC__) && ( __GLIBC__ < 2 || __GLIBC__ == 2 && __GLIBC_MINOR__ < 5 )
 #define NPTL_PTHREAD_EXIT_BUG	1
 #endif