From 89e6b0f97a053519d98014a4f0a2ea8275a5dce1 Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Tue, 13 Jun 2017 09:50:48 +0100
Subject: [PATCH] Use nice file permission constants, fix readme paths

---
 README.md                       | 7 ++++---
 kernel_module/anonymous_inode.c | 2 +-
 kernel_module/debugfs.c         | 3 ++-
 kernel_module/fops.c            | 3 ++-
 kernel_module/poll.c            | 3 ++-
 5 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 61c7813..25845f7 100644
--- a/README.md
+++ b/README.md
@@ -319,8 +319,9 @@ But TODO I don't think you can see where you are in the kernel source code and l
             1.  [panic](kernel_module/panic.c)
         1.  [params](kernel_module/params.c)
         1.  [fops](kernel_module/fops.c)
-            1. [ioctl](ioctl.c)
-            1. [poll](poll.c)
+            1. [ioctl](kernel_module/ioctl.c)
+            1. [poll](kernel_module/poll.c)
+            1. [anonymous_inode](kernel_module/anonymous_inode.c)
         1.  Asynchronous
             1. [workqueue](kernel_module/workqueue.c)
             1. [sleep](kernel_module/sleep.c)
@@ -329,7 +330,7 @@ But TODO I don't think you can see where you are in the kernel source code and l
             1. [schedule](kernel_module/schedule.c)
             1. [timer](kernel_module/timer.c)
             1. [work_from_work](kernel_module/work_from_work.c)
-        1.  [irq](irq.c)
+        1.  [irq](kernel_module/irq.c)
         1.  Module dependencies
             1. [dep.c](kernel_module/dep.c)
             1. [dep2.c](kernel_module/dep2.c)
diff --git a/kernel_module/anonymous_inode.c b/kernel_module/anonymous_inode.c
index 3ac3ebc..3b962c9 100644
--- a/kernel_module/anonymous_inode.c
+++ b/kernel_module/anonymous_inode.c
@@ -4,7 +4,7 @@ https://stackoverflow.com/questions/4508998/what-is-anonymous-inode
 anon_inode_getfd example:
 
 - get an anonymous inode via ioctl from a debugfs entry
-- read from that inode
+- read jiffies from that inode
 
 This method allows getting multiple file descriptors from a single filesystem,
 which reduces namespace pollution.
diff --git a/kernel_module/debugfs.c b/kernel_module/debugfs.c
index f2861ea..c588284 100644
--- a/kernel_module/debugfs.c
+++ b/kernel_module/debugfs.c
@@ -11,6 +11,7 @@ Requires `CONFIG_DEBUG_FS=y`.
 #include <linux/debugfs.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <uapi/linux/stat.h> /* S_IRUSR */
 
 MODULE_LICENSE("GPL");
 
@@ -25,7 +26,7 @@ static int myinit(void)
 		printk(KERN_ALERT "debugfs_create_dir failed");
 		return -1;
 	}
-	file = debugfs_create_u32("myfile", 0666, dir, &value);
+	file = debugfs_create_u32("myfile", S_IRUSR, dir, &value);
 	if (!file) {
 		printk(KERN_ALERT "debugfs_create_u32 failed");
 		return -1;
diff --git a/kernel_module/fops.c b/kernel_module/fops.c
index 2b8767d..d7c5c6d 100644
--- a/kernel_module/fops.c
+++ b/kernel_module/fops.c
@@ -24,6 +24,7 @@ Here we use debugfs.
 #include <linux/kernel.h> /* min */
 #include <linux/module.h>
 #include <linux/printk.h> /* printk */
+#include <uapi/linux/stat.h> /* S_IRUSR */
 
 MODULE_LICENSE("GPL");
 
@@ -138,7 +139,7 @@ static const struct file_operations fops = {
 static int myinit(void)
 {
 	dir = debugfs_create_dir("lkmc_fops", 0);
-	debugfs_create_file("f", 0666, dir, NULL, &fops);
+	debugfs_create_file("f", S_IRUSR | S_IWUSR, dir, NULL, &fops);
 	return 0;
 }
 
diff --git a/kernel_module/poll.c b/kernel_module/poll.c
index 9cca31d..38e80e1 100644
--- a/kernel_module/poll.c
+++ b/kernel_module/poll.c
@@ -16,6 +16,7 @@ Outcome: user echoes jiffies every second.
 #include <linux/poll.h>
 #include <linux/printk.h> /* printk */
 #include <linux/wait.h> /* wait_queue_head_t, wait_event_interruptible, wake_up_interruptible  */
+#include <uapi/linux/stat.h> /* S_IRUSR */
 
 MODULE_LICENSE("GPL");
 
@@ -71,7 +72,7 @@ static const struct file_operations fops = {
 static int myinit(void)
 {
 	dir = debugfs_create_dir("lkmc_poll", 0);
-	debugfs_create_file("f", 0666, dir, NULL, &fops);
+	debugfs_create_file("f", S_IRUSR | S_IWUSR, dir, NULL, &fops);
 	init_waitqueue_head(&waitqueue);
 	kthread = kthread_create(kthread_func, NULL, "mykthread");
 	wake_up_process(kthread);