Add initial cut at /sys/kernel/echo/*HEADmaster

The idea is you can do

echo "foo" > /sys/kernel/echo/debug

or whatever and the kernel will printk it

1 files changed, 102 insertions, 2 deletions

diff --git a/kecho.c b/kecho.c
index cbdbb40..7bae6d2 100644
--- a/kecho.c
+++ b/kecho.c
@@ -1,14 +1,114 @@
-#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
 #include <linux/init.h>
+#include <linux/kdev_t.h>
+#include <linux/module.h>
+
+static struct kobject *echo_kobj;
+
+static ssize_t echo_show(struct kobject *kobj, struct kobj_attribute *attr,
+		         char *buf)
+{
+	return 0;
+}
+
+static ssize_t echo_store(struct kobject *kobj, struct kobj_attribute *attr,
+		          const char *buf, size_t count)
+{
+	ssize_t ret;
+
+	if (count > INT_MAX) {
+		count = INT_MAX;
+	}
+
+	if (strcmp (attr->attr.name, "emergency") == 0) {
+		ret = printk(KERN_EMERG "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "alert") == 0) {
+		ret = printk(KERN_ALERT "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "critical") == 0) {
+		ret = printk(KERN_CRIT "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "error") == 0) {
+		ret = printk(KERN_ERR "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "warning") == 0) {
+		ret = printk(KERN_WARNING "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "notice") == 0) {
+		ret = printk(KERN_NOTICE "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "info") == 0) {
+		ret = printk(KERN_INFO "%*s", (int) count, buf);
+	} else if (strcmp (attr->attr.name, "debug") == 0) {
+		ret = printk(KERN_DEBUG "%*s", (int) count, buf);
+	} else {
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static struct kobj_attribute emergency_attribute =
+	__ATTR(emergency, 0200, echo_show, echo_store);
+
+static struct kobj_attribute alert_attribute =
+	__ATTR(alert, 0200, echo_show, echo_store);
+
+static struct kobj_attribute critical_attribute =
+	__ATTR(critical, 0200, echo_show, echo_store);
+
+static struct kobj_attribute error_attribute =
+	__ATTR(error, 0200, echo_show, echo_store);
+
+static struct kobj_attribute warning_attribute =
+	__ATTR(warning, 0200, echo_show, echo_store);
+
+static struct kobj_attribute notice_attribute =
+	__ATTR(notice, 0200, echo_show, echo_store);
+
+static struct kobj_attribute info_attribute =
+	__ATTR(info, 0200, echo_show, echo_store);
+
+static struct kobj_attribute debug_attribute =
+	__ATTR(debug, 0200, echo_show, echo_store);
+
+static struct attribute *echo_attributes[] = {
+	&emergency_attribute.attr,
+	&alert_attribute.attr,
+	&critical_attribute.attr,
+	&error_attribute.attr,
+	&warning_attribute.attr,
+	&notice_attribute.attr,
+	&info_attribute.attr,
+	&debug_attribute.attr,
+	NULL
+};
+
+static struct attribute_group echo_attribute_group = {
+	.attrs = echo_attributes
+};
 
 MODULE_LICENSE("GPL");
 static int __init kecho_init(void)
 {
-      return 0;
+	int ret;
+
+	ret = 0;
+
+	echo_kobj = kobject_create_and_add("echo", kernel_kobj);
+
+	if (echo_kobj == NULL) {
+		ret = -ENOMEM;
+	}
+
+	if (!ret)
+		ret = sysfs_create_group(echo_kobj, &echo_attribute_group);
+
+	if (ret)
+		kobject_put(echo_kobj);
+
+	return ret;
 }
 
 static void __exit kecho_cleanup(void)
 {
+	kobject_put(echo_kobj);
 }
 
 module_init(kecho_init);