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authorRickard Green <rickard@erlang.org>2010-02-03 01:11:38 +0000
committerErlang/OTP <otp@erlang.org>2010-02-03 01:11:38 +0000
commit768da5a5f6312496b9b8a09cca5ea1d6b89a2c1c (patch)
treebb7f0b01f75f5f21dcb2f402e2d01b1665a21c2b
parent153e2047d734297df3c55b6fa8bda83fb33c72bd (diff)
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OTP-8386 Immediately repeated multi-scheduling block/unblock cycles using
erlang:system_flag(multi_scheduling, block | unblock) could deadlock the runtime system.
-rw-r--r--erts/emulator/beam/erl_process.c38
1 files changed, 29 insertions, 9 deletions
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index b519b39d63..2789691c55 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -2765,7 +2765,7 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
p->flags |= F_HAVE_BLCKD_MSCHED;
ASSERT(erts_smp_atomic_read(&schdlr_sspnd.active) == 1);
ASSERT(p->scheduler_data->no == 1);
- res = 1;
+ res = ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED;
}
else {
p->flags |= F_HAVE_BLCKD_MSCHED;
@@ -2896,12 +2896,16 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
#endif
p->flags &= ~F_HAVE_BLCKD_MSCHED;
erts_smp_atomic_set(&schdlr_sspnd.msb.ongoing, 0);
- if (schdlr_sspnd.online == 1)
- /* No schedulers to resume */;
+ if (schdlr_sspnd.online == 1) {
+ /* No schedulers to resume */
+ ASSERT(erts_smp_atomic_read(&schdlr_sspnd.active) == 1);
+ schdlr_sspnd.changing = 0;
+ }
else if (erts_common_run_queue) {
for (ix = 1; ix < schdlr_sspnd.online; ix++)
erts_smp_atomic_set(&ERTS_SCHEDULER_IX(ix)->suspended, 0);
wake_all_schedulers();
+ erts_smp_cnd_broadcast(&schdlr_sspnd.cnd);
}
else {
int online = schdlr_sspnd.online;
@@ -2933,8 +2937,8 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all)
erts_smp_runq_unlock(ERTS_RUNQ_IX(0));
erts_smp_mtx_unlock(&balance_info.update_mtx);
erts_smp_mtx_lock(&schdlr_sspnd.mtx);
+ erts_smp_cnd_broadcast(&schdlr_sspnd.cnd);
}
- erts_smp_cnd_broadcast(&schdlr_sspnd.cnd);
res = ERTS_SCHDLR_SSPND_DONE;
}
}
@@ -8033,11 +8037,6 @@ erts_do_exit_process(Process* p, Eterm reason)
if (p->bif_timers)
erts_cancel_bif_timers(p, ERTS_PROC_LOCKS_ALL);
-#ifdef ERTS_SMP
- if (p->flags & F_HAVE_BLCKD_MSCHED)
- erts_block_multi_scheduling(p, ERTS_PROC_LOCKS_ALL, 0, 1);
-#endif
-
erts_smp_proc_unlock(p, ERTS_PROC_LOCKS_ALL_MINOR);
#ifdef ERTS_SMP
@@ -8082,6 +8081,27 @@ continue_exit_process(Process *p
erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
#endif
+#ifdef ERTS_SMP
+ if (p->flags & F_HAVE_BLCKD_MSCHED) {
+ ErtsSchedSuspendResult ssr;
+ ssr = erts_block_multi_scheduling(p, ERTS_PROC_LOCK_MAIN, 0, 1);
+ switch (ssr) {
+ case ERTS_SCHDLR_SSPND_YIELD_RESTART:
+ goto yield;
+ case ERTS_SCHDLR_SSPND_DONE_MSCHED_BLOCKED:
+ case ERTS_SCHDLR_SSPND_YIELD_DONE_MSCHED_BLOCKED:
+ case ERTS_SCHDLR_SSPND_DONE:
+ case ERTS_SCHDLR_SSPND_YIELD_DONE:
+ p->flags &= ~F_HAVE_BLCKD_MSCHED;
+ break;
+ case ERTS_SCHDLR_SSPND_EINVAL:
+ default:
+ erl_exit(ERTS_ABORT_EXIT, "%s:%d: Internal error: %d\n",
+ __FILE__, __LINE__, (int) ssr);
+ }
+ }
+#endif
+
if (p->flags & F_USING_DB) {
if (erts_db_process_exiting(p, ERTS_PROC_LOCK_MAIN))
goto yield;