Fixed second issue reported in https://bugs.llvm.org/show_bug.cgi?id=41584.
Added synchronization for possible concurrent initialization of mutexes
by multiple threads. The need of synchronization caused by commit r357927
which added the use of mutexes at threads movement to/from common pool
(earlier the mutexes were used only at suspend/resume).
Patch by Johnny Peyton.
Differential Revision: https://reviews.llvm.org/D61995
llvm-svn: 360919
diff --git a/openmp/runtime/src/z_Linux_util.cpp b/openmp/runtime/src/z_Linux_util.cpp
index 9e08db3..7eb782a 100644
--- a/openmp/runtime/src/z_Linux_util.cpp
+++ b/openmp/runtime/src/z_Linux_util.cpp
@@ -1354,9 +1354,20 @@
void __kmp_suspend_initialize_thread(kmp_info_t *th) {
ANNOTATE_HAPPENS_AFTER(&th->th.th_suspend_init_count);
- if (th->th.th_suspend_init_count <= __kmp_fork_count) {
- /* this means we haven't initialized the suspension pthread objects for this
- thread in this instance of the process */
+ int old_value = KMP_ATOMIC_LD_RLX(&th->th.th_suspend_init_count);
+ int new_value = __kmp_fork_count + 1;
+ // Return if already initialized
+ if (old_value == new_value)
+ return;
+ // Wait, then return if being initialized
+ if (old_value == -1 ||
+ !__kmp_atomic_compare_store(&th->th.th_suspend_init_count, old_value,
+ -1)) {
+ while (KMP_ATOMIC_LD_ACQ(&th->th.th_suspend_init_count) != new_value) {
+ KMP_CPU_PAUSE();
+ }
+ } else {
+ // Claim to be the initializer and do initializations
int status;
status = pthread_cond_init(&th->th.th_suspend_cv.c_cond,
&__kmp_suspend_cond_attr);
@@ -1364,13 +1375,13 @@
status = pthread_mutex_init(&th->th.th_suspend_mx.m_mutex,
&__kmp_suspend_mutex_attr);
KMP_CHECK_SYSFAIL("pthread_mutex_init", status);
- *(volatile int *)&th->th.th_suspend_init_count = __kmp_fork_count + 1;
+ KMP_ATOMIC_ST_REL(&th->th.th_suspend_init_count, new_value);
ANNOTATE_HAPPENS_BEFORE(&th->th.th_suspend_init_count);
}
}
void __kmp_suspend_uninitialize_thread(kmp_info_t *th) {
- if (th->th.th_suspend_init_count > __kmp_fork_count) {
+ if (KMP_ATOMIC_LD_ACQ(&th->th.th_suspend_init_count) > __kmp_fork_count) {
/* this means we have initialize the suspension pthread objects for this
thread in this instance of the process */
int status;
@@ -1384,7 +1395,8 @@
KMP_SYSFAIL("pthread_mutex_destroy", status);
}
--th->th.th_suspend_init_count;
- KMP_DEBUG_ASSERT(th->th.th_suspend_init_count == __kmp_fork_count);
+ KMP_DEBUG_ASSERT(KMP_ATOMIC_LD_RLX(&th->th.th_suspend_init_count) ==
+ __kmp_fork_count);
}
}