1 files changed, 154 insertions, 0 deletions
diff --git a/drivers/infiniband/sw/rxe/rxe_task.c b/drivers/infiniband/sw/rxe/rxe_task.c
new file mode 100644
index 000000000..446ee2c3d
--- /dev/null
+++ b/drivers/infiniband/sw/rxe/rxe_task.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/*
+ * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
+ * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/hardirq.h>
+
+#include "rxe.h"
+
+int __rxe_do_task(struct rxe_task *task)
+
+{
+	int ret;
+
+	while ((ret = task->func(task->arg)) == 0)
+		;
+
+	task->ret = ret;
+
+	return ret;
+}
+
+/*
+ * this locking is due to a potential race where
+ * a second caller finds the task already running
+ * but looks just after the last call to func
+ */
+void rxe_do_task(struct tasklet_struct *t)
+{
+	int cont;
+	int ret;
+	struct rxe_task *task = from_tasklet(task, t, tasklet);
+	unsigned int iterations = RXE_MAX_ITERATIONS;
+
+	spin_lock_bh(&task->state_lock);
+	switch (task->state) {
+	case TASK_STATE_START:
+		task->state = TASK_STATE_BUSY;
+		spin_unlock_bh(&task->state_lock);
+		break;
+
+	case TASK_STATE_BUSY:
+		task->state = TASK_STATE_ARMED;
+		fallthrough;
+	case TASK_STATE_ARMED:
+		spin_unlock_bh(&task->state_lock);
+		return;
+
+	default:
+		spin_unlock_bh(&task->state_lock);
+		pr_warn("%s failed with bad state %d\n", __func__, task->state);
+		return;
+	}
+
+	do {
+		cont = 0;
+		ret = task->func(task->arg);
+
+		spin_lock_bh(&task->state_lock);
+		switch (task->state) {
+		case TASK_STATE_BUSY:
+			if (ret) {
+				task->state = TASK_STATE_START;
+			} else if (iterations--) {
+				cont = 1;
+			} else {
+				/* reschedule the tasklet and exit
+				 * the loop to give up the cpu
+				 */
+				tasklet_schedule(&task->tasklet);
+				task->state = TASK_STATE_START;
+			}
+			break;
+
+		/* someone tried to run the task since the last time we called
+		 * func, so we will call one more time regardless of the
+		 * return value
+		 */
+		case TASK_STATE_ARMED:
+			task->state = TASK_STATE_BUSY;
+			cont = 1;
+			break;
+
+		default:
+			pr_warn("%s failed with bad state %d\n", __func__,
+				task->state);
+		}
+		spin_unlock_bh(&task->state_lock);
+	} while (cont);
+
+	task->ret = ret;
+}
+
+int rxe_init_task(struct rxe_task *task, void *arg, int (*func)(void *))
+{
+	task->arg	= arg;
+	task->func	= func;
+	task->destroyed	= false;
+
+	tasklet_setup(&task->tasklet, rxe_do_task);
+
+	task->state = TASK_STATE_START;
+	spin_lock_init(&task->state_lock);
+
+	return 0;
+}
+
+void rxe_cleanup_task(struct rxe_task *task)
+{
+	bool idle;
+
+	/*
+	 * Mark the task, then wait for it to finish. It might be
+	 * running in a non-tasklet (direct call) context.
+	 */
+	task->destroyed = true;
+
+	do {
+		spin_lock_bh(&task->state_lock);
+		idle = (task->state == TASK_STATE_START);
+		spin_unlock_bh(&task->state_lock);
+	} while (!idle);
+
+	tasklet_kill(&task->tasklet);
+}
+
+void rxe_run_task(struct rxe_task *task)
+{
+	if (task->destroyed)
+		return;
+
+	rxe_do_task(&task->tasklet);
+}
+
+void rxe_sched_task(struct rxe_task *task)
+{
+	if (task->destroyed)
+		return;
+
+	tasklet_schedule(&task->tasklet);
+}
+
+void rxe_disable_task(struct rxe_task *task)
+{
+	tasklet_disable(&task->tasklet);
+}
+
+void rxe_enable_task(struct rxe_task *task)
+{
+	tasklet_enable(&task->tasklet);
+}