Linux内核kobject模型(添加kobject对象，模拟kobject状态变化)

#include <linux/module.h>#include <linux/kernel.h>#include <linux/kobject.h>#include <linux/sysfs.h>#include <linux/slab.h>#include <linux/err.h>static struct kobject *parent;static struct kobject *child;static struct kset *c_kset;static unsigned long flag = 1;static ssize_t att_show(struct kobject *kobj, struct attribute *attr, char *buf){size_t count = 0;count += sprintf(&buf[count], "%lu\n", flag);return count;}static ssize_t att_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count){flag = buf[0] - '0';switch(flag){case 0:kobject_uevent(kobj, KOBJ_ADD);break;case 1:kobject_uevent(kobj, KOBJ_REMOVE);break;case 2:kobject_uevent(kobj, KOBJ_CHANGE);break;case 3:kobject_uevent(kobj, KOBJ_MOVE);break;case 4:kobject_uevent(kobj, KOBJ_ONLINE);break;case 5:kobject_uevent(kobj, KOBJ_OFFLINE);break;}return count;}static struct attribute cld_att = {.name = "cldattr",.mode = S_IRUGO | S_IWUSR,};static const struct sysfs_ops att_ops = {.show = att_show,.store = att_store,};static struct kobj_type cld_ktype = {.sysfs_ops = &att_ops,};static int kobj_demo_init(void){int err;parent = kobject_create_and_add("pa_obj", NULL);child = kzalloc(sizeof(*child), GFP_KERNEL);if(!child)return PTR_ERR(child);c_kset = kset_create_and_add("c_kset", NULL, parent);if(!c_kset)return -1;child->kset = c_kset;err = kobject_init_and_add(child, &cld_ktype, parent, "cld_obj");if (err)return err;err = sysfs_create_file(child, &cld_att);return err;}static void kobj_demo_exit(void){sysfs_remove_file(child, &cld_att);kset_unregister(c_kset);kobject_del(child);kobject_del(parent);}module_init(kobj_demo_init);module_exit(kobj_demo_exit);MODULE_LICENSE("GPL");MODULE_AUTHOR("FORSAKENING-HDU");MODULE_DESCRIPTION("KOBJECT TEST");

Makefile:

obj-m:=kobject-test.oKERNELDIR:=/lib/modules/$(shell uname -r)/buildPWD:=$(shell pwd)default:        $(MAKE) -C$(KERNELDIR) M=$(PWD)clean:        rm -f *.o *.ko *.mod.*

用户态模拟/sbin/hotplug的函数为：

#include <stdio.h>#include <syslog.h>extern char **environ;int main(int argc, char **argv){        char **var;        syslog(LOG_INFO | LOG_LOCAL0, "------------------------\n");        syslog(LOG_INFO | LOG_LOCAL0, "argv[1]=%s\n", argv[1]);        for (var = environ; *var != NULL; ++var)                syslog(LOG_INFO | LOG_LOCAL0, "env=%s\n", *var);        syslog(LOG_INFO | LOG_LOCAL0, "------------------------\n");        return 0;}

将这个函数编为hotplug添加为/sbin/hotplug， 并且echo "sbin/hotplug" > /proc/sys/kernel/hotpug

当运行insmod kobject-test.ko时候，在/var/log/message中打印：

[root@zx kobject]# echo "sbin/hotplug" > /proc/sys/kernel/hotplug [root@zx kobject]# rmmod kobject-test.ko [root@zx kobject]# cat /dev/null > /var/log/messages[root@zx kobject]# insmod kobject-test.ko [root@zx kobject]# cat /var/log/messagesOct  5 12:22:23 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:28 zx hotplug: ------------------------Oct  5 12:22:28 zx hotplug: argv[1]=moduleOct  5 12:22:28 zx hotplug: env=ACTION=addOct  5 12:22:28 zx hotplug: env=DEVPATH=/module/kobject_testOct  5 12:22:28 zx hotplug: env=SUBSYSTEM=moduleOct  5 12:22:28 zx hotplug: env=SEQNUM=1374Oct  5 12:22:28 zx hotplug: env=HOME=/Oct  5 12:22:28 zx hotplug: env=PATH=/sbin:/bin:/usr/sbin:/usr/binOct  5 12:22:28 zx hotplug: ------------------------Oct  5 12:22:28 zx kernel: __ratelimit: 40 callbacks suppressed

修改child的属性文件cldattr来模拟kobject的状态变化：

[root@zx kobject]# echo '0' > /sys/pa_obj/cld_obj/cldattr [root@zx kobject]# echo '1' > /sys/pa_obj/cld_obj/cldattr [root@zx kobject]# echo '2' > /sys/pa_obj/cld_obj/cldattr [root@zx kobject]# cat /var/log/messagesOct  5 12:22:23 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:28 zx hotplug: ------------------------Oct  5 12:22:28 zx hotplug: argv[1]=moduleOct  5 12:22:28 zx hotplug: env=ACTION=addOct  5 12:22:28 zx hotplug: env=DEVPATH=/module/kobject_testOct  5 12:22:28 zx hotplug: env=SUBSYSTEM=moduleOct  5 12:22:28 zx hotplug: env=SEQNUM=1374Oct  5 12:22:28 zx hotplug: env=HOME=/Oct  5 12:22:28 zx hotplug: env=PATH=/sbin:/bin:/usr/sbin:/usr/binOct  5 12:22:28 zx hotplug: ------------------------Oct  5 12:22:28 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:33 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:38 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:43 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:49 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:49 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:22:52 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:22:54 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:22:59 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:01 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:04 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:09 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:09 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:11 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:14 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:15 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:17 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:19 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:19 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:23 zx pulseaudio[3186]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.Oct  5 12:23:24 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:29 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:35 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:40 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:45 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:50 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:55 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:23:57 zx hotplug: ------------------------Oct  5 12:23:57 zx hotplug: argv[1]=c_ksetOct  5 12:23:57 zx hotplug: env=ACTION=addOct  5 12:23:57 zx hotplug: env=DEVPATH=/pa_obj/cld_objOct  5 12:23:57 zx hotplug: env=SUBSYSTEM=c_ksetOct  5 12:23:57 zx hotplug: env=SEQNUM=1375Oct  5 12:23:57 zx hotplug: env=HOME=/Oct  5 12:23:57 zx hotplug: env=PATH=/sbin:/bin:/usr/sbin:/usr/binOct  5 12:23:57 zx hotplug: ------------------------Oct  5 12:24:00 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:24:01 zx hotplug: ------------------------Oct  5 12:24:01 zx hotplug: argv[1]=c_ksetOct  5 12:24:01 zx hotplug: env=ACTION=removeOct  5 12:24:01 zx hotplug: env=DEVPATH=/pa_obj/cld_objOct  5 12:24:01 zx hotplug: env=SUBSYSTEM=c_ksetOct  5 12:24:01 zx hotplug: env=SEQNUM=1376Oct  5 12:24:01 zx hotplug: env=HOME=/Oct  5 12:24:01 zx hotplug: env=PATH=/sbin:/bin:/usr/sbin:/usr/binOct  5 12:24:01 zx hotplug: ------------------------Oct  5 12:24:05 zx hotplug: ------------------------Oct  5 12:24:05 zx hotplug: argv[1]=c_ksetOct  5 12:24:05 zx hotplug: env=ACTION=changeOct  5 12:24:05 zx hotplug: env=DEVPATH=/pa_obj/cld_objOct  5 12:24:05 zx hotplug: env=SUBSYSTEM=c_ksetOct  5 12:24:05 zx hotplug: env=SEQNUM=1377Oct  5 12:24:05 zx hotplug: env=HOME=/Oct  5 12:24:05 zx hotplug: env=PATH=/sbin:/bin:/usr/sbin:/usr/binOct  5 12:24:05 zx hotplug: ------------------------Oct  5 12:24:05 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:24:10 zx kernel: __ratelimit: 40 callbacks suppressedOct  5 12:24:15 zx kernel: __ratelimit: 40 callbacks suppressed[root@zx kobject]# 

参考：深入Linux设备驱动程序内核机制 - 陈学松