[rtems-libbsd commit] EPOCH(9): Fix epoch call and drain

[Sebastian Huber]

Module:    rtems-libbsd
Branch:    6-freebsd-12
Commit:    158c270deda0b5a0f8e533120e14a7cddc388228
Changeset: http://git.rtems.org/rtems-libbsd/commit/?id=158c270deda0b5a0f8e533120e14a7cddc388228

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Fri Jun 11 07:40:49 2021 +0200

EPOCH(9): Fix epoch call and drain

Since the epoch call callbacks may lock/unlock a mutex the callbacks must be
called from within thread context with thread dispatching enabled.  Use thread
pinning to ensure that the calling thread stays on the right processor.  Use
the interrupt server to ensure the thread context for the epoch drain.

---

 rtemsbsd/rtems/rtems-kernel-epoch.c | 39 +++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/rtemsbsd/rtems/rtems-kernel-epoch.c b/rtemsbsd/rtems/rtems-kernel-epoch.c
index 0c070bd..642b585 100644
--- a/rtemsbsd/rtems/rtems-kernel-epoch.c
+++ b/rtemsbsd/rtems/rtems-kernel-epoch.c
@@ -349,15 +349,29 @@ epoch_call(epoch_t epoch, epoch_context_t ctx,
     void (*callback) (epoch_context_t))
 {
 	Per_CPU_Control *cpu_self;
-	struct epoch_record *er;
 	struct epoch_pcpu *epcpu;
+	struct epoch_record *er;
+#ifdef RTEMS_SMP
+	ISR_Level level;
+	Thread_Control *executing;
+
+	_ISR_Local_disable(level);
+	cpu_self = _Per_CPU_Get();
+	executing = _Per_CPU_Get_executing(cpu_self);
+	_Thread_Pin(executing);
+	_ISR_Local_enable(level);
+#endif
 
-	cpu_self = _Thread_Dispatch_disable();
 	epcpu = PER_CPU_DATA_GET(cpu_self, struct epoch_pcpu, epoch);
 	epcpu->cb_count += 1;
 	er = EPOCH_GET_RECORD(cpu_self, epoch);
 	ck_epoch_call(&er->er_record, ctx, callback);
+
+#ifdef RTEMS_SMP
+	cpu_self = _Thread_Dispatch_disable();
+	_Thread_Unpin(executing, cpu_self);
 	_Thread_Dispatch_enable(cpu_self);
+#endif
 }
 
 #ifdef INVARIANTS
@@ -411,7 +425,7 @@ epoch_call_drain_cb(void *arg)
 	struct epoch_record *er;
 
 	epoch = arg;
-	cpu = _Per_CPU_Get();
+	cpu = _Per_CPU_Get_snapshot();
 	er = EPOCH_GET_RECORD(cpu, epoch);
 	epoch_call(epoch, &er->er_drain_ctx, epoch_drain_cb);
 }
@@ -425,6 +439,7 @@ epoch_drain_callbacks(epoch_t epoch)
 	uint32_t cpu_max;
 	rtems_id id;
 	rtems_status_code sc;
+	rtems_interrupt_server_request req[CPU_MAXIMUM_PROCESSORS];
 #else
 	struct epoch_record *er;
 #endif
@@ -433,6 +448,7 @@ epoch_drain_callbacks(epoch_t epoch)
 	mtx_lock(&epoch->e_drain_mtx);
 
 #ifdef RTEMS_SMP
+	memset(&req, 0, sizeof(req));
 	cpu_max = rtems_scheduler_get_processor_maximum();
 
 	for (cpu_index = 0; cpu_index <= cpu_max; ++cpu_index) {
@@ -445,8 +461,15 @@ epoch_drain_callbacks(epoch_t epoch)
 	for (cpu_index = 0; cpu_index <= cpu_max; ++cpu_index) {
 		sc = rtems_scheduler_ident_by_processor(cpu_index, &id);
 		if (sc == RTEMS_SUCCESSFUL) {
-			_SMP_Unicast_action(cpu_index, epoch_call_drain_cb,
+			sc = rtems_interrupt_server_request_initialize(
+			    cpu_index, &req[cpu_index], epoch_call_drain_cb,
 			    epoch);
+			if (sc == RTEMS_SUCCESSFUL) {
+				rtems_interrupt_server_request_submit(
+				    &req[cpu_index]);
+			} else {
+				panic("no interrupt server for epoch drain");
+			}
 		}
 	}
 #else
@@ -461,4 +484,12 @@ epoch_drain_callbacks(epoch_t epoch)
 
 	mtx_unlock(&epoch->e_drain_mtx);
 	sx_xunlock(&epoch->e_drain_sx);
+
+#ifdef RTEMS_SMP
+	for (cpu_index = 0; cpu_index <= cpu_max; ++cpu_index) {
+		if (req[cpu_index].action.handler != NULL) {
+			rtems_interrupt_server_request_destroy(&req[cpu_index]);
+		}
+	}
+#endif
 }