Merge siva.hindu.god:/home/tsmith/m/bk/mrg-jan17/50

into  siva.hindu.god:/home/tsmith/m/bk/mrg-jan17/maint/50

1 files changed, 39 insertions, 0 deletions

diff --git a/mysys/my_thr_init.c b/mysys/my_thr_init.c
index b44e5ced99f..c5105dc4e1e 100644
--- a/mysys/my_thr_init.c
+++ b/mysys/my_thr_init.c
@@ -46,6 +46,23 @@ 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
 
@@ -64,6 +81,28 @@ 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
   /*