[Openmp-commits] [openmp] r277991 - __kmp_free_task: Fix for serial explicit tasks producing proxy tasks
Jonas Hahnfeld via Openmp-commits
openmp-commits at lists.llvm.org
Mon Aug 8 03:08:07 PDT 2016
Author: hahnfeld
Date: Mon Aug 8 05:08:07 2016
New Revision: 277991
URL: http://llvm.org/viewvc/llvm-project?rev=277991&view=rev
Log:
__kmp_free_task: Fix for serial explicit tasks producing proxy tasks
Consider the following code which may be executed by a serial team:
int dep;
#pragma omp target nowait depend(out: dep)
{
sleep(1);
}
#pragma omp task depend(in: dep)
{
#pragma omp target nowait
{
sleep(1);
}
}
Here the explicit task may not be freed until the nested proxy task has
finished. The current code hasn't considered this and called __kmp_free_task
anyway which triggered an assert because of remaining incomplete children:
KMP_DEBUG_ASSERT( TCR_4(taskdata->td_incomplete_child_tasks) == 0 );
Differential Revision: https://reviews.llvm.org/D23115
Added:
openmp/trunk/runtime/test/tasking/bug_nested_proxy_task.c
Modified:
openmp/trunk/runtime/src/kmp_tasking.c
Modified: openmp/trunk/runtime/src/kmp_tasking.c
URL: http://llvm.org/viewvc/llvm-project/openmp/trunk/runtime/src/kmp_tasking.c?rev=277991&r1=277990&r2=277991&view=diff
==============================================================================
--- openmp/trunk/runtime/src/kmp_tasking.c (original)
+++ openmp/trunk/runtime/src/kmp_tasking.c Mon Aug 8 05:08:07 2016
@@ -576,15 +576,13 @@ __kmp_free_task( kmp_int32 gtid, kmp_tas
static void
__kmp_free_task_and_ancestors( kmp_int32 gtid, kmp_taskdata_t * taskdata, kmp_info_t * thread )
{
- kmp_int32 children = 0;
- kmp_int32 team_or_tasking_serialized = taskdata -> td_flags.team_serial || taskdata -> td_flags.tasking_ser;
-
+ // Proxy tasks must always be allowed to free their parents
+ // because they can be run in background even in serial mode.
+ kmp_int32 task_serial = taskdata->td_flags.task_serial && !taskdata->td_flags.proxy;
KMP_DEBUG_ASSERT( taskdata -> td_flags.tasktype == TASK_EXPLICIT );
- if ( !team_or_tasking_serialized ) {
- children = KMP_TEST_THEN_DEC32( (kmp_int32 *)(& taskdata -> td_allocated_child_tasks) ) - 1;
- KMP_DEBUG_ASSERT( children >= 0 );
- }
+ kmp_int32 children = KMP_TEST_THEN_DEC32( (kmp_int32 *)(& taskdata -> td_allocated_child_tasks) ) - 1;
+ KMP_DEBUG_ASSERT( children >= 0 );
// Now, go up the ancestor tree to see if any ancestors can now be freed.
while ( children == 0 )
@@ -599,16 +597,14 @@ __kmp_free_task_and_ancestors( kmp_int32
taskdata = parent_taskdata;
- // Stop checking ancestors at implicit task or if tasking serialized
+ // Stop checking ancestors at implicit task
// instead of walking up ancestor tree to avoid premature deallocation of ancestors.
- if ( team_or_tasking_serialized || taskdata -> td_flags.tasktype == TASK_IMPLICIT )
+ if ( task_serial || taskdata -> td_flags.tasktype == TASK_IMPLICIT )
return;
- if ( !team_or_tasking_serialized ) {
- // Predecrement simulated by "- 1" calculation
- children = KMP_TEST_THEN_DEC32( (kmp_int32 *)(& taskdata -> td_allocated_child_tasks) ) - 1;
- KMP_DEBUG_ASSERT( children >= 0 );
- }
+ // Predecrement simulated by "- 1" calculation
+ children = KMP_TEST_THEN_DEC32( (kmp_int32 *)(& taskdata -> td_allocated_child_tasks) ) - 1;
+ KMP_DEBUG_ASSERT( children >= 0 );
}
KA_TRACE(20, ("__kmp_free_task_and_ancestors(exit): T#%d task %p has %d children; "
Added: openmp/trunk/runtime/test/tasking/bug_nested_proxy_task.c
URL: http://llvm.org/viewvc/llvm-project/openmp/trunk/runtime/test/tasking/bug_nested_proxy_task.c?rev=277991&view=auto
==============================================================================
--- openmp/trunk/runtime/test/tasking/bug_nested_proxy_task.c (added)
+++ openmp/trunk/runtime/test/tasking/bug_nested_proxy_task.c Mon Aug 8 05:08:07 2016
@@ -0,0 +1,128 @@
+// RUN: %libomp-compile -lpthread && %libomp-run
+#include <stdio.h>
+#include <omp.h>
+#include <pthread.h>
+#include "omp_my_sleep.h"
+
+/*
+ With task dependencies one can generate proxy tasks from an explicit task
+ being executed by a serial task team. The OpenMP runtime library didn't
+ expect that and tries to free the explicit task that is the parent of the
+ proxy task still working in background. It therefore has incomplete children
+ which triggers a debugging assertion.
+*/
+
+// Compiler-generated code (emulation)
+typedef long kmp_intptr_t;
+typedef int kmp_int32;
+
+typedef char bool;
+
+typedef struct ident {
+ kmp_int32 reserved_1; /**< might be used in Fortran; see above */
+ kmp_int32 flags; /**< also f.flags; KMP_IDENT_xxx flags; KMP_IDENT_KMPC identifies this union member */
+ kmp_int32 reserved_2; /**< not really used in Fortran any more; see above */
+#if USE_ITT_BUILD
+ /* but currently used for storing region-specific ITT */
+ /* contextual information. */
+#endif /* USE_ITT_BUILD */
+ kmp_int32 reserved_3; /**< source[4] in Fortran, do not use for C++ */
+ char const *psource; /**< String describing the source location.
+ The string is composed of semi-colon separated fields which describe the source file,
+ the function and a pair of line numbers that delimit the construct.
+ */
+} ident_t;
+
+typedef struct kmp_depend_info {
+ kmp_intptr_t base_addr;
+ size_t len;
+ struct {
+ bool in:1;
+ bool out:1;
+ } flags;
+} kmp_depend_info_t;
+
+struct kmp_task;
+typedef kmp_int32 (* kmp_routine_entry_t)( kmp_int32, struct kmp_task * );
+
+typedef struct kmp_task { /* GEH: Shouldn't this be aligned somehow? */
+ void * shareds; /**< pointer to block of pointers to shared vars */
+ kmp_routine_entry_t routine; /**< pointer to routine to call for executing task */
+ kmp_int32 part_id; /**< part id for the task */
+} kmp_task_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+kmp_int32 __kmpc_global_thread_num ( ident_t * );
+kmp_task_t*
+__kmpc_omp_task_alloc( ident_t *loc_ref, kmp_int32 gtid, kmp_int32 flags,
+ size_t sizeof_kmp_task_t, size_t sizeof_shareds,
+ kmp_routine_entry_t task_entry );
+void __kmpc_proxy_task_completed_ooo ( kmp_task_t *ptask );
+kmp_int32 __kmpc_omp_task_with_deps ( ident_t *loc_ref, kmp_int32 gtid, kmp_task_t * new_task,
+ kmp_int32 ndeps, kmp_depend_info_t *dep_list,
+ kmp_int32 ndeps_noalias, kmp_depend_info_t *noalias_dep_list );
+kmp_int32
+__kmpc_omp_task( ident_t *loc_ref, kmp_int32 gtid, kmp_task_t * new_task );
+#ifdef __cplusplus
+}
+#endif
+
+void *target(void *task)
+{
+ my_sleep( 0.1 );
+ __kmpc_proxy_task_completed_ooo((kmp_task_t*) task);
+ return NULL;
+}
+
+pthread_t target_thread;
+
+// User's code
+int task_entry(kmp_int32 gtid, kmp_task_t *task)
+{
+ pthread_create(&target_thread, NULL, &target, task);
+ return 0;
+}
+
+int main()
+{
+ int dep;
+
+#pragma omp taskgroup
+{
+/*
+ * Corresponds to:
+ #pragma omp target nowait depend(out: dep)
+ {
+ my_sleep( 0.1 );
+ }
+*/
+ kmp_depend_info_t dep_info;
+ dep_info.base_addr = (long) &dep;
+ dep_info.len = sizeof(int);
+ // out = inout per spec and runtime expects this
+ dep_info.flags.in = 1;
+ dep_info.flags.out = 1;
+
+ kmp_int32 gtid = __kmpc_global_thread_num(NULL);
+ kmp_task_t *proxy_task = __kmpc_omp_task_alloc(NULL,gtid,17,sizeof(kmp_task_t),0,&task_entry);
+ __kmpc_omp_task_with_deps(NULL,gtid,proxy_task,1,&dep_info,0,NULL);
+
+ #pragma omp task depend(in: dep)
+ {
+/*
+ * Corresponds to:
+ #pragma omp target nowait depend(out: dep)
+ {
+ my_sleep( 0.1 );
+ }
+*/
+ kmp_task_t *nested_proxy_task = __kmpc_omp_task_alloc(NULL,gtid,17,sizeof(kmp_task_t),0,&task_entry);
+ __kmpc_omp_task(NULL,gtid,nested_proxy_task);
+ }
+}
+
+ // only check that it didn't crash
+ return 0;
+}
More information about the Openmp-commits
mailing list