[Openmp-commits] [openmp] r266674 - Fix for pthread_setspecific (TLS and shutdown) problem

[Jonathan Peyton via Openmp-commits]

Author: jlpeyton
Date: Mon Apr 18 16:33:01 2016
New Revision: 266674

URL: http://llvm.org/viewvc/llvm-project?rev=266674&view=rev
Log:
Fix for pthread_setspecific (TLS and shutdown) problem

Some codes that use TLS fail intermittently because one thread tries to write
TLS values after the TLS key has been destroyed by another thread. This happens
when one thread executes library shutdown (and destroys TLS keys), while another
thread starts to execute the TLS key destructor routine. Before this change, the
kmp_init_runtime flag was checked before calling pthread_* TLS functions, but
this flag is set to FALSE later than the destruction of the TLS keys, which
leads to failure. The fix is to check kmp_init_gtid instead, as this flag is
unset *before* the destruction of TLS keys.

Differential Revision: http://reviews.llvm.org/D19022

Modified:
    openmp/trunk/runtime/src/kmp_runtime.c
    openmp/trunk/runtime/src/z_Linux_util.c
    openmp/trunk/runtime/src/z_Windows_NT_util.c

Modified: openmp/trunk/runtime/src/kmp_runtime.c
URL: http://llvm.org/viewvc/llvm-project/openmp/trunk/runtime/src/kmp_runtime.c?rev=266674&r1=266673&r2=266674&view=diff
==============================================================================
--- openmp/trunk/runtime/src/kmp_runtime.c (original)
+++ openmp/trunk/runtime/src/kmp_runtime.c Mon Apr 18 16:33:01 2016
@@ -3737,6 +3737,7 @@ __kmp_register_root( int initial_thread
 
     /* initialize the thread, get it ready to go */
     __kmp_initialize_info( root_thread, root->r.r_root_team, 0, gtid );
+    TCW_4(__kmp_init_gtid, TRUE);
 
     /* prepare the master thread for get_gtid() */
     __kmp_gtid_set_specific( gtid );
@@ -3748,7 +3749,6 @@ __kmp_register_root( int initial_thread
     #endif
     __kmp_create_worker( gtid, root_thread, __kmp_stksize );
     KMP_DEBUG_ASSERT( __kmp_gtid_get_specific() == gtid );
-    TCW_4(__kmp_init_gtid, TRUE);
 
     KA_TRACE( 20, ("__kmp_register_root: T#%d init T#%d(%d:%d) arrived: join=%u, plain=%u\n",
                     gtid, __kmp_gtid_from_tid( 0, root->r.r_hot_team ),

Modified: openmp/trunk/runtime/src/z_Linux_util.c
URL: http://llvm.org/viewvc/llvm-project/openmp/trunk/runtime/src/z_Linux_util.c?rev=266674&r1=266673&r2=266674&view=diff
==============================================================================
--- openmp/trunk/runtime/src/z_Linux_util.c (original)
+++ openmp/trunk/runtime/src/z_Linux_util.c Mon Apr 18 16:33:01 2016
@@ -1897,18 +1897,21 @@ __kmp_yield( int cond )
 void
 __kmp_gtid_set_specific( int gtid )
 {
-    int status;
-    KMP_ASSERT( __kmp_init_runtime );
-    status = pthread_setspecific( __kmp_gtid_threadprivate_key, (void*)(intptr_t)(gtid+1) );
-    KMP_CHECK_SYSFAIL( "pthread_setspecific", status );
+    if( __kmp_init_gtid ) {
+        int status;
+        status = pthread_setspecific( __kmp_gtid_threadprivate_key, (void*)(intptr_t)(gtid+1) );
+        KMP_CHECK_SYSFAIL( "pthread_setspecific", status );
+    } else {
+        KA_TRACE( 50, ("__kmp_gtid_set_specific: runtime shutdown, returning\n" ) );
+    }
 }
 
 int
 __kmp_gtid_get_specific()
 {
     int gtid;
-    if ( !__kmp_init_runtime ) {
-        KA_TRACE( 50, ("__kmp_get_specific: runtime shutdown, returning KMP_GTID_SHUTDOWN\n" ) );
+    if ( !__kmp_init_gtid ) {
+        KA_TRACE( 50, ("__kmp_gtid_get_specific: runtime shutdown, returning KMP_GTID_SHUTDOWN\n" ) );
         return KMP_GTID_SHUTDOWN;
     }
     gtid = (int)(size_t)pthread_getspecific( __kmp_gtid_threadprivate_key );

Modified: openmp/trunk/runtime/src/z_Windows_NT_util.c
URL: http://llvm.org/viewvc/llvm-project/openmp/trunk/runtime/src/z_Windows_NT_util.c?rev=266674&r1=266673&r2=266674&view=diff
==============================================================================
--- openmp/trunk/runtime/src/z_Windows_NT_util.c (original)
+++ openmp/trunk/runtime/src/z_Windows_NT_util.c Mon Apr 18 16:33:01 2016
@@ -507,19 +507,22 @@ __kmp_yield( int cond )
 void
 __kmp_gtid_set_specific( int gtid )
 {
-    KA_TRACE( 50, ("__kmp_gtid_set_specific: T#%d key:%d\n",
-                gtid, __kmp_gtid_threadprivate_key ));
-    KMP_ASSERT( __kmp_init_runtime );
-    if( ! TlsSetValue( __kmp_gtid_threadprivate_key, (LPVOID)(gtid+1)) )
-        KMP_FATAL( TLSSetValueFailed );
+    if( __kmp_init_gtid ) {
+        KA_TRACE( 50, ("__kmp_gtid_set_specific: T#%d key:%d\n",
+                    gtid, __kmp_gtid_threadprivate_key ));
+        if( ! TlsSetValue( __kmp_gtid_threadprivate_key, (LPVOID)(gtid+1)) )
+            KMP_FATAL( TLSSetValueFailed );
+    } else {
+        KA_TRACE( 50, ("__kmp_gtid_set_specific: runtime shutdown, returning\n" ) );
+    }
 }
 
 int
 __kmp_gtid_get_specific()
 {
     int gtid;
-    if( !__kmp_init_runtime ) {
-        KA_TRACE( 50, ("__kmp_get_specific: runtime shutdown, returning KMP_GTID_SHUTDOWN\n" ) );
+    if( !__kmp_init_gtid ) {
+        KA_TRACE( 50, ("__kmp_gtid_get_specific: runtime shutdown, returning KMP_GTID_SHUTDOWN\n" ) );
         return KMP_GTID_SHUTDOWN;
     }
     gtid = (int)(kmp_intptr_t)TlsGetValue( __kmp_gtid_threadprivate_key );