Initial s390-tools-2.0.0 import

This commit is based on the s390-tools-1.39.0 version.

Changes on top of s390-tools-1.39.0:

 - Add MIT license to all source files
 - Add LICENSE file
 - Transform REAMDE to README.md (markdown)
 - Add AUTHORS.md file
 - Add CONTRIBUTING.md file
 - Move changelog from README to CHANGELOG.md file

Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>

cpuplugd/mem.c

@@ -0,0 +1,82 @@
+/*
+ * cpuplugd - Linux for System z Hotplug Daemon
+ *
+ * cmm functions
+ *
+ * Copyright IBM Corp. 2007, 2017
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include "cpuplugd.h"
+
+/*
+ * The cmm_pages value defines the size of the balloon of blocked memory.
+ * Increasing the value is removing memory from Linux, which is an memunplug.
+ * Decreasing the value is adding memory back to Linux, which is memplug.
+ */
+
+/*
+ * Set the value of cmm_pages
+ */
+void set_cmm_pages(long pages)
+{
+	FILE *filp;
+
+	filp = fopen("/proc/sys/vm/cmm_pages", "w");
+	if (!filp)
+		cpuplugd_exit("Cannot open /proc/sys/vm/cmmpages: %s\n",
+			      strerror(errno));
+	cpuplugd_debug("changing number of pages permanently reserved to %ld\n",
+		       pages);
+	fprintf(filp, "%ld\n", pages);
+	fclose(filp);
+	return;
+}
+
+/*
+ * Read number of pages permanently reserved
+ */
+long get_cmmpages_size()
+{
+	FILE *filp;
+	long size;
+	int rc;
+
+	filp = fopen("/proc/sys/vm/cmm_pages", "r");
+	if (!filp)
+		cpuplugd_exit("Cannot open /proc/sys/vm/cmm_pages: %s\n",
+			      strerror(errno));
+	rc = fscanf(filp, "%ld", &size);
+	if (rc == 0)
+		cpuplugd_exit("Can not read /proc/sys/vm/cmm_pages: %s\n",
+			      strerror(errno));
+	fclose(filp);
+	return size;
+}
+
+/*
+ * Reset cmm pagesize to value we found prior to daemon startup
+ */
+void cleanup_cmm()
+{
+	set_cmm_pages(cmm_pagesize_start);
+	return;
+}
+
+/*
+ * Function to check if the cmm kernel module is loaded and the required
+ * files below /proc exit
+ */
+int check_cmmfiles(void)
+{
+	FILE *filp;
+
+	filp = fopen("/proc/sys/vm/cmm_pages", "r");
+	if (!filp)
+		return -1;
+	fclose(filp);
+	return 0;
+}
+