Add GEC lock mechanism.

Basically re-use the gec lock code from flashrom package.

BUG=chrome-os-partner:12319
TEST=Build and run on link. Only build on snow.
while true; do ectool hello; done &   ; run 10 instances.
                                      ; expect all instances runs okay.

Signed-off-by: Louis Yung-Chieh Lo <yjlou@chromium.org>
Change-Id: I11d5824f46810c6f5a04a564a81387cdea081697
Reviewed-on: https://gerrit.chromium.org/gerrit/29763
Reviewed-by: Randall Spangler <rspangler@chromium.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/util/lock/locks.h b/util/lock/locks.h
new file mode 100644
index 0000000000..39dfc933f3
--- /dev/null
+++ b/util/lock/locks.h
@@ -0,0 +1,47 @@
+/* Copyright 2012, Google Inc.
+ * All rights reserved.
+ *
+ * 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.
+ *    * Neither the name of Google Inc. nor the names of its
+ *      contributors may be used to endorse or promote products derived
+ *      from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef LOCKS_H__
+#define LOCKS_H__
+
+/* this is the base key, since we have to pick something global */
+#define IPC_LOCK_KEY	(0x67736c00 & 0xfffffc00) /* 22 bits "gsl" */
+
+/* The ordering of the following keys matters a lot. We don't want to reorder
+ * keys and have a new binary dependent on deployed/used because it will break
+ * atomicity of existing users and binaries. In other words, DO NOT REORDER. */
+
+/* this is the "big lock". */
+#define BIGLOCK		(IPC_LOCK_KEY + 0)
+
+/* for Google EC */
+#define GECLOCK		(IPC_LOCK_KEY + 1)
+
+#endif /* LOCKS_H__ */