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| author | Jonathan Peyton <jonathan.l.peyton@intel.com> | 2018-08-24 18:07:35 +0000 |
|---|---|---|
| committer | Jonathan Peyton <jonathan.l.peyton@intel.com> | 2018-08-24 18:07:35 +0000 |
| commit | 7b6f5e63dc8397451f858259d8d90271b6e6ba4a (patch) | |
| tree | 4a1d7b0c666ebd2794aa0a3cf43e32e3b46885c0 /openmp | |
| parent | 9367d3ecd7522369a57c57955811a00abf874527 (diff) | |
[OpenMP] Fix tasking bug for decreasing hot team nthreads
The __kmp_execute_tasks_template() function reads the task_team and
current_task from the thread structure. There appears to be a pathological
timing where the number of threads in the hot team decreases and so a
thread is put in the pool via __kmp_free_thread(). It could be the case that:
1) A thread reads th_task_team into task_team local variables
and is then interrupted by the OS
2) Master frees the thread and sets current task and task team to NULL
3) The thread reads current_task as NULL
When this happens, current_task is dereferenced and a segfault occurs.
This patch just checks for current_task to not be NULL as well.
Differential Revision: https://reviews.llvm.org/D50651
Diffstat (limited to 'openmp')
| -rw-r--r-- | openmp/runtime/src/kmp_tasking.cpp | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/openmp/runtime/src/kmp_tasking.cpp b/openmp/runtime/src/kmp_tasking.cpp index d9220c5a2dc..e1b03f780b5 100644 --- a/openmp/runtime/src/kmp_tasking.cpp +++ b/openmp/runtime/src/kmp_tasking.cpp @@ -2469,7 +2469,7 @@ static inline int __kmp_execute_tasks_template( KMP_DEBUG_ASSERT(__kmp_tasking_mode != tskm_immediate_exec); KMP_DEBUG_ASSERT(thread == __kmp_threads[gtid]); - if (task_team == NULL) + if (task_team == NULL || current_task == NULL) return FALSE; KA_TRACE(15, ("__kmp_execute_tasks_template(enter): T#%d final_spin=%d " |