[PATCH rdma-next 12/29] IB/rxe: RXE tasks handling

Moni Shoua
2016-06-02T16:57:20Z

A 'task' is a short function that returns 0 as long as it needs to be
called again. rxe tasks are based on the kernel's tasklet infrastructure.

Signed-off-by: Kamal Heib <kamalh-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Amir Vadai <amirv-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Moni Shoua <monis-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Reviewed-by: Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
drivers/infiniband/hw/rxe/rxe_task.c | 154 +++++++++++++++++++++++++++++++++++
drivers/infiniband/hw/rxe/rxe_task.h | 95 +++++++++++++++++++++
2 files changed, 249 insertions(+)
create mode 100644 drivers/infiniband/hw/rxe/rxe_task.c
create mode 100644 drivers/infiniband/hw/rxe/rxe_task.h

diff --git a/drivers/infiniband/hw/rxe/rxe_task.c b/drivers/infiniband/hw/rxe/rxe_task.c
new file mode 100644
index 0000000..1e19bf8
--- /dev/null
+++ b/drivers/infiniband/hw/rxe/rxe_task.c
@@ -0,0 +1,154 @@
+/*
+ * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
+ * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/hardirq.h>
+
+#include "rxe_task.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(unsigned long data)
+{
+ int cont;
+ int ret;
+ unsigned long flags;
+ struct rxe_task *task = (struct rxe_task *)data;
+
+ spin_lock_irqsave(&task->state_lock, flags);
+ switch (task->state) {
+ case TASK_STATE_START:
+ task->state = TASK_STATE_BUSY;
+ spin_unlock_irqrestore(&task->state_lock, flags);
+ break;
+
+ case TASK_STATE_BUSY:
+ task->state = TASK_STATE_ARMED;
+ /* fall through to */
+ case TASK_STATE_ARMED:
+ spin_unlock_irqrestore(&task->state_lock, flags);
+ return;
+
+ default:
+ spin_unlock_irqrestore(&task->state_lock, flags);
+ pr_warn("bad state = %d in rxe_do_task\n", task->state);
+ return;
+ }
+
+ do {
+ cont = 0;
+ ret = task->func(task->arg);
+
+ spin_lock_irqsave(&task->state_lock, flags);
+ switch (task->state) {
+ case TASK_STATE_BUSY:
+ if (ret)
+ task->state = TASK_STATE_START;
+ else
+ cont = 1;
+ break;
+
+ /* soneone 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("bad state = %d in rxe_do_task\n",
+ task->state);
+ }
+ spin_unlock_irqrestore(&task->state_lock, flags);
+ } while (cont);
+
+ task->ret = ret;
+}
+
+int rxe_init_task(void *obj, struct rxe_task *task,
+ void *arg, int (*func)(void *), char *name)
+{
+ task->obj = obj;
+ task->arg = arg;
+ task->func = func;
+ snprintf(task->name, sizeof(task->name), "%s", name);
+
+ tasklet_init(&task->tasklet, rxe_do_task, (unsigned long)task);
+
+ task->state = TASK_STATE_START;
+ spin_lock_init(&task->state_lock);
+
+ return 0;
+}
+
+void rxe_cleanup_task(struct rxe_task *task)
+{
+ tasklet_kill(&task->tasklet);
+}
+
+void rxe_run_task(struct rxe_task *task, int sched)
+{
+ if (sched)
+ tasklet_schedule(&task->tasklet);
+ else
+ rxe_do_task((unsigned long)task);
+}
+
+void rxe_disable_task(struct rxe_task *task)
+{
+ tasklet_disable(&task->tasklet);
+}
+
+void rxe_enable_task(struct rxe_task *task)
+{
+ tasklet_enable(&task->tasklet);
+}
diff --git a/drivers/infiniband/hw/rxe/rxe_task.h b/drivers/infiniband/hw/rxe/rxe_task.h
new file mode 100644
index 0000000..d14aa6d
--- /dev/null
+++ b/drivers/infiniband/hw/rxe/rxe_task.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
+ * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef RXE_TASK_H
+#define RXE_TASK_H
+
+enum {
+ TASK_STATE_START = 0,
+ TASK_STATE_BUSY = 1,
+ TASK_STATE_ARMED = 2,
+};
+
+/*
+ * data structure to describe a 'task' which is a short
+ * function that returns 0 as long as it needs to be
+ * called again.
+ */
+struct rxe_task {
+ void *obj;
+ struct tasklet_struct tasklet;
+ int state;
+ spinlock_t state_lock; /* spinlock for task state */
+ void *arg;
+ int (*func)(void *arg);
+ int ret;
+ char name[16];
+};
+
+/*
+ * init rxe_task structure
+ * arg => parameter to pass to fcn
+ * fcn => function to call until it returns != 0
+ */
+int rxe_init_task(void *obj, struct rxe_task *task,
+ void *arg, int (*func)(void *), char *name);
+
+/* cleanup task */
+void rxe_cleanup_task(struct rxe_task *task);
+
+/*
+ * raw call to func in loop without any checking
+ * can call when tasklets are disabled
+ */
+int __rxe_do_task(struct rxe_task *task);
+
+/*
+ * common function called by any of the main tasklets
+ * If there is any chance that there is additional
+ * work to do someone must reschedule the task before
+ * leaving
+ */
+void rxe_do_task(unsigned long data);
+
+/* run a task, else schedule it to run as a tasklet, The decision
+ * to run or schedule tasklet is based on the parameter sched.
+ */
+void rxe_run_task(struct rxe_task *task, int sched);
+
+/* keep a task from scheduling */
+void rxe_disable_task(struct rxe_task *task);
+
+/* allow task to run */
+void rxe_enable_task(struct rxe_task *task);
+
+#endif /* RXE_TASK_H */
--
1.8.3.1