Signed-off-by: Thomas Schoebel-Theuer <t...@schoebel-theuer.de>
---
drivers/staging/mars/lamport.c | 61 ++++++++++++++++++++++++++++++++++++++++++
include/linux/brick/lamport.h | 26 ++++++++++++++++++
2 files changed, 87 insertions(+)
create mode 100644 drivers/staging/mars/lamport.c
create mode 100644 include/linux/brick/lamport.h
diff --git a/drivers/staging/mars/lamport.c b/drivers/staging/mars/lamport.c
new file mode 100644
index 000000000000..373093f6e35f
--- /dev/null
+++ b/drivers/staging/mars/lamport.c
@@ -0,0 +1,61 @@
+/*
+ * MARS Long Distance Replication Software
+ *
+ * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
+ * Copyright (C) 2011-2014 1&1 Internet AG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/semaphore.h>
+
+#include <linux/brick/lamport.h>
+
+/* TODO: replace with spinlock if possible (first check) */
+struct semaphore lamport_sem = __SEMAPHORE_INITIALIZER(lamport_sem, 1);
+struct timespec lamport_now = {};
+
+void get_lamport(struct timespec *now)
+{
+ int diff;
+
+ down(&lamport_sem);
+
+ *now = CURRENT_TIME;
+ diff = timespec_compare(now, &lamport_now);
+ if (diff >= 0) {
+ timespec_add_ns(now, 1);
+ memcpy(&lamport_now, now, sizeof(lamport_now));
+ timespec_add_ns(&lamport_now, 1);
+ } else {
+ timespec_add_ns(&lamport_now, 1);
+ memcpy(now, &lamport_now, sizeof(*now));
+ }
+
+ up(&lamport_sem);
+}
+
+void set_lamport(struct timespec *old)
+{
+ int diff;
+
+ down(&lamport_sem);
+
+ diff = timespec_compare(old, &lamport_now);
+ if (diff >= 0) {
+ memcpy(&lamport_now, old, sizeof(lamport_now));
+ timespec_add_ns(&lamport_now, 1);
+ }
+
+ up(&lamport_sem);
+}
diff --git a/include/linux/brick/lamport.h b/include/linux/brick/lamport.h
new file mode 100644
index 000000000000..9aac0ce01bb4
--- /dev/null
+++ b/include/linux/brick/lamport.h
@@ -0,0 +1,26 @@
+/*
+ * MARS Long Distance Replication Software
+ *
+ * Copyright (C) 2010-2014 Thomas Schoebel-Theuer
+ * Copyright (C) 2011-2014 1&1 Internet AG
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef LAMPORT_H
+#define LAMPORT_H
+
+#include <linux/time.h>
+
+extern void get_lamport(struct timespec *now);
+extern void set_lamport(struct timespec *old);
+
+#endif
--
2.11.0
