Created
December 16, 2018 10:02
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Linux-4.19.9でのカーネルモジュール作成サンプル。
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/* | |
* hello.c - kernel module sample with sysctl value | |
*/ | |
#include <linux/kernel.h> | |
#include <linux/module.h> | |
#include <linux/seq_file.h> | |
static struct ctl_table_header *hello_sysctl_header; | |
static int value; | |
module_param(value, int, 0); | |
static struct hello_sysctl_settings { | |
int value; | |
} hello_sysctl_settings; | |
// "sysctl -w hello.value=<N>" や "cat /proc/sys/hello/value" 時に呼ばれる。 | |
// 書き換えられた値に対して処理を行う場合は、この関数内で処理する。 | |
static int hello_sysctl_handler(struct ctl_table *ctl, int write, | |
void __user *buffer, size_t *lenp, loff_t *ppos) | |
{ | |
int ret = proc_dointvec(ctl, write, buffer, lenp, ppos); | |
printk("-=> hello_sysctl_handler()\n"); | |
if (write) { | |
if (hello_sysctl_settings.value == 777) { | |
printk(" (^_^)/\n"); | |
} | |
} | |
return ret; | |
} | |
// /proc/sys/hello/value のprocfsを設定する。 | |
static struct ctl_table hello_table[] = { | |
{ | |
.procname = "value", | |
.data = &hello_sysctl_settings.value, | |
.maxlen = sizeof(int), | |
.mode = 0644, | |
.proc_handler = hello_sysctl_handler, | |
}, | |
{ } | |
}; | |
static struct ctl_table hello_root_table[] = { | |
{ | |
.procname = "hello", | |
.maxlen = 0, | |
.mode = 0555, | |
.child = hello_table, | |
}, | |
{ } | |
}; | |
// sysctl変数の登録。 | |
static void hello_sysctl_register(void) | |
{ | |
static int initialized; | |
printk("-=> hello_sysctl_register()\n"); | |
if (initialized == 1) | |
return; | |
hello_sysctl_header = register_sysctl_table(hello_root_table); | |
hello_sysctl_settings.value = 0; // 初期値の設定 | |
initialized = 1; | |
} | |
static void hello_sysctl_unregister(void) | |
{ | |
printk("-=> hello_sysctl_unregister()\n"); | |
if (hello_sysctl_header) | |
unregister_sysctl_table(hello_sysctl_header); | |
} | |
static int hello_init(void) | |
{ | |
printk("-=> hello_init()\n"); | |
hello_sysctl_register(); | |
return 0; | |
} | |
static void hello_exit(void) | |
{ | |
printk("-=> hello_exit()\n"); | |
hello_sysctl_unregister(); | |
} | |
module_init(hello_init); | |
module_exit(hello_exit); | |
MODULE_LICENSE("GPL"); | |
MODULE_INFO(hello, "Y"); |
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