kern/llsync: new module

This module provides lockless synchronization so that reads can safely occur
during updates, without holding a lock. It is based on passive serialization
as described in US patent 4809168, and achieves a goal similar to Linux RCU
(Read-Copy Update).

1 files changed, 32 insertions, 0 deletions

diff --git a/kern/llsync_i.h b/kern/llsync_i.h
new file mode 100644
index 00000000..89a7fe83
--- /dev/null
+++ b/kern/llsync_i.h
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2013 Richard Braun.
+ *
+ * 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 3 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _KERN_LLSYNC_I_H
+#define _KERN_LLSYNC_I_H
+
+#include <kern/param.h>
+
+/*
+ * Per-processor flag indicating if a processor checked in.
+ */
+struct llsync_cpu_checkpoint {
+    int checked;
+} __aligned(CPU_L1_SIZE);
+
+extern struct llsync_cpu_checkpoint llsync_cpu_checkpoints[MAX_CPUS];
+
+#endif /* _KERN_LLSYNC_I_H */