Merge pull request #6 from d-grossman/master

Added an example of using the proc filesystem (add more linux kernel programs #2)

procfs_hw/Makefile

@@ -0,0 +1,7 @@
+obj-m += procfs_hw.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

procfs_hw/procfs_hw.c

@@ -0,0 +1,63 @@
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+
+#include <linux/fs.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+#define procfs_msg "Hello World\n"
+#define procfs_name "procfs_hw"
+#define procfs_parent NULL
+#define procfs_perms 0644
+
+static struct proc_dir_entry *procfs_hw_file;
+
+static int
+procfs_hw_show (struct seq_file *m, void *v)
+{
+  seq_printf (m, "%s\n", procfs_msg);
+
+  return 0;
+}
+
+static int
+procfs_hw_open (struct inode *inode, struct file *file)
+{
+  return single_open (file, procfs_hw_show, NULL);
+}
+
+static const struct file_operations procfs_hw_fops = {
+  .owner = THIS_MODULE,
+  .open = procfs_hw_open,
+  .read = seq_read,
+  .llseek = seq_lseek,
+  .release = single_release,
+};
+
+static int __init
+procfs_hw_init (void)
+{
+  procfs_hw_file =
+    proc_create (procfs_name, procfs_perms, procfs_parent, &procfs_hw_fops);
+
+  if (!procfs_hw_file)
+    {
+      return -ENOMEM;
+    }
+
+  return 0;
+}
+
+static void __exit
+procfs_hw_exit (void)
+{
+  remove_proc_entry ("procfs_hw", procfs_parent);
+}
+
+module_init (procfs_hw_init);
+module_exit (procfs_hw_exit);
+
+MODULE_LICENSE ("GPL");
+MODULE_AUTHOR ("d-grossman");
+MODULE_DESCRIPTION ("procfs hello world");