Use module_init, mention modprobe on readme

README.md

@@ -41,6 +41,14 @@ After the first build, you can also run just:
 
 to save a few seconds. `./run` wouldn't rebuild everything, but checking timestamps takes a few moments.
 
+If you are feeling fancy, you can also insert modules with:
+
+    modprobe hello
+
+and if you are feeling raw, you can use:
+
+    /myinsmod.out /hello.ko
+
 We use `printk` a lot, and it shows on the QEMU terminal by default. If that annoys you (e.g. you want to see stdout separately), do:
 
     dmesg -n 1
@@ -299,6 +307,7 @@ But TODO I don't think you can see where you are in the kernel source code and l
 1.  [Introduction](introduction.md)
 1.  [Build](build.md)
 1.  [kmod](kmod.md)
+1.  []
 1.  [Bibliography](bibliography.md)
 1.  Examples
     1.  [Host](host/)

kernel_module/debugfs.c

@@ -17,7 +17,7 @@ MODULE_LICENSE("GPL");
 static struct dentry *dir;
 static u32 value = 42;
 
-int init_module(void)
+static int myinit(void)
 {
     struct dentry *file;
     dir = debugfs_create_dir("lkmc_debugfs", 0);
@@ -33,7 +33,10 @@ int init_module(void)
     return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
     debugfs_remove_recursive(dir);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/fops.c

@@ -136,7 +136,7 @@ static const struct file_operations fops = {
 	.write = fop_write,
 };
 
-int init_module(void)
+static int myinit(void)
 {
 	struct dentry *file;
 	dir = debugfs_create_dir("lkmc_fops", 0);
@@ -152,7 +152,10 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	debugfs_remove_recursive(dir);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/hello.c

@@ -5,7 +5,7 @@ Hello world module.
 	insmod hello.ko
 	dmesg -c | grep 'hello init'
 	rmmod hello.ko
-	dmesg -c | grep 'hello cleanup'
+	dmesg -c | grep 'hello exit'
 */
 
 #include <linux/module.h>
@@ -13,13 +13,16 @@ Hello world module.
 
 MODULE_LICENSE("GPL");
 
-int init_module(void)
+static int myinit(void)
 {
 	printk(KERN_INFO "hello init\n");
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
-	printk(KERN_INFO "hello cleanup\n");
+	printk(KERN_INFO "hello exit\n");
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/hello2.c

@@ -9,13 +9,16 @@ Mostly to check that our build infrastructure can handle more than one module!
 
 MODULE_LICENSE("GPL");
 
-int init_module(void)
+static int myinit(void)
 {
 	printk(KERN_INFO "hello2 init\n");
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
-	printk(KERN_INFO "hello2 cleanup\n");
+	printk(KERN_INFO "hello2 exit\n");
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/irq.c

@@ -23,7 +23,7 @@ static irqreturn_t handler(int i, void *v)
 	return IRQ_HANDLED;
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	irqreturn_t r;
 	r = request_irq(
@@ -37,6 +37,9 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/kthread.c

@@ -31,15 +31,18 @@ static int work_func(void *data)
 	return 0;
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	kthread = kthread_create(work_func, NULL, "mykthread");
 	wake_up_process(kthread);
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	/* Waits for thread to return. */
 	kthread_stop(kthread);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/kthreads.c

@@ -37,7 +37,7 @@ static int work_func2(void *data)
 	return 0;
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	kthread1 = kthread_create(work_func1, NULL, "mykthread1");
 	kthread2 = kthread_create(work_func2, NULL, "mykthread2");
@@ -46,8 +46,11 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	kthread_stop(kthread1);
 	kthread_stop(kthread2);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/module_init.c

@@ -1,9 +1,13 @@
 /*
-Hello world with module_init / exit macros.
+https://stackoverflow.com/questions/3218320/what-is-the-difference-between-module-init-and-init-module-in-a-linux-kernel-mod
 
-TODO: vs direct init_module and cleanup_module.
+Hello world with direct init_module and cleantup_module.
 
-- modprobe only works with the macros. Try "modprobe module_init".
+This appears to be an older method that still works but has some drawbacks.
+
+vs module_init and module_exit?
+
+- modprobe only works with the module_init / module_exit. Try "modprobe module_init".
 */
 
 #include <linux/module.h>
@@ -11,16 +15,13 @@ TODO: vs direct init_module and cleanup_module.
 
 MODULE_LICENSE("GPL");
 
-static int module_init_init(void)
+int init_module(void)
 {
-	pr_info("module_init init\n");
+	printk(KERN_INFO "init_module\n");
 	return 0;
 }
 
-static void module_init_exit(void)
+void cleanup_module(void)
 {
-	pr_info("module_exit cleanup\n");
+	printk(KERN_INFO "cleanup_module\n");
 }
-
-module_init(module_init_init)
-module_exit(module_init_exit)

kernel_module/panic.c

@@ -13,14 +13,17 @@ The alternative is to get the serial data out streamed to console or to a file:
 #include <linux/module.h>
 #include <linux/kernel.h>
 
-int init_module(void)
+static int myinit(void)
 {
 	printk(KERN_INFO "panic init\n");
 	panic("hello panic");
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	printk(KERN_INFO "panic cleanup\n");
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/params.c

@@ -47,14 +47,17 @@ static int work_func(void *data)
 	return 0;
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	kthread = kthread_create(work_func, NULL, "mykthread");
 	wake_up_process(kthread);
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	kthread_stop(kthread);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/poll.c

@@ -61,7 +61,7 @@ static const struct file_operations fops = {
 	.poll = poll
 };
 
-int init_module(void)
+static int myinit(void)
 {
 	dir = debugfs_create_dir("lkmc_poll", 0);
     debugfs_create_file("f", 0666, dir, NULL, &fops);
@@ -70,7 +70,10 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	debugfs_remove_recursive(dir);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/schedule.c

@@ -5,6 +5,8 @@ kthreads only allow interrupting if you call schedule.
 
 If you don't, they just run forever, and you have to kill the VM.
 
+Sleep functions like usleep_range also end up calling schedule.
+
 Test with:
 
 	dmesg -n 1
@@ -19,7 +21,6 @@ Then:
 - 	yn=1: all good
 */
 
-#include <linux/delay.h> /* usleep_range */
 #include <linux/kernel.h>
 #include <linux/kthread.h>
 #include <linux/module.h>
@@ -45,14 +46,17 @@ static int work_func(void *data)
 	return 0;
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	kthread = kthread_create(work_func, NULL, "mykthread");
 	wake_up_process(kthread);
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	kthread_stop(kthread);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/sleep.c

@@ -32,7 +32,7 @@ static void work_func(struct work_struct *work)
 	}
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	DECLARE_WORK(work, work_func);
 	queue = create_workqueue("myworkqueue");
@@ -40,8 +40,11 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	atomic_set(&run, 0);
 	destroy_workqueue(queue);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/timer.c

@@ -28,14 +28,17 @@ static void callback(unsigned long data)
 	mod_timer(&mytimer, jiffies + onesec);
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	onesec = msecs_to_jiffies(1000);
 	mod_timer(&mytimer, jiffies + onesec);
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	del_timer(&mytimer);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/wait_queue.c

@@ -46,7 +46,7 @@ static int kthread_func2(void *data)
 	return 0;
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	init_waitqueue_head(&queue);
 	kthread1 = kthread_create(kthread_func1, NULL, "mykthread1");
@@ -56,8 +56,11 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	kthread_stop(kthread1);
 	kthread_stop(kthread2);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/work_from_work.c

@@ -21,7 +21,7 @@ static void work_func(struct work_struct *work)
 	queue_delayed_work(queue, &next_work, HZ);
 }
 
-int init_module(void)
+static int myinit(void)
 {
 	DECLARE_WORK(work, work_func);
 	queue = create_workqueue("myworkqueue");
@@ -29,7 +29,10 @@ int init_module(void)
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	destroy_workqueue(queue);
 }
+
+module_init(myinit)
+module_exit(myexit)

kernel_module/workqueue_cheat.c

@@ -32,15 +32,18 @@ static void work_func(struct work_struct *work)
 
 DECLARE_WORK(work, work_func);
 
-int init_module(void)
+static int myinit(void)
 {
 	queue = create_singlethread_workqueue("myworkqueue");
 	queue_work(queue, &work);
 	return 0;
 }
 
-void cleanup_module(void)
+static void myexit(void)
 {
 	/* Waits for jobs to finish. */
 	destroy_workqueue(queue);
 }
+
+module_init(myinit)
+module_exit(myexit)

kmod.md

@@ -1,6 +1,10 @@
 # kmod
 
-Implements `lsmod`, `insmod`, `rmmod`, and other tools.
+Multi-call executable that implements: `lsmod`, `insmod`, `rmmod`, and other tools.
+
+BusyBox also implements its own version of those executables.
+
+Source: <https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git>
 
 The other tools are just symlinks to it.
 
@@ -77,7 +81,12 @@ Remove a module. Takes either the module name or the `.ko` file:
 
 ## modprobe
 
-List available modules relative path to `/lib/modules/VERSION/`:
+Vs `insmod`:
+
+- <https://askubuntu.com/questions/20070/whats-the-difference-between-insmod-and-modprobe>
+- <https://stackoverflow.com/questions/22891705/whats-the-difference-between-insmod-and-modprobe>
+
+List available modules relative path to `/lib/modules/$KERNEL_VERSION/`:
 
     sudo modprobe -l