如果模块A要发信息给模块B,可采用内核通知链的方式,这里提供最简单的例子。
notifier_chain.c
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/export.h>
static BLOCKING_NOTIFIER_HEAD(test_chain_head);
int register_test_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&test_chain_head, nb);
}
EXPORT_SYMBOL(register_test_notifier);
int unregister_test_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_unregister(&test_chain_head, nb);
}
EXPORT_SYMBOL(unregister_test_notifier);
int test_notifier_call_chain(unsigned long val)
{
int ret;
ret = blocking_notifier_call_chain(&test_chain_head, val, NULL);
return notifier_to_errno(ret);
}
EXPORT_SYMBOL(test_notifier_call_chain);
MODULE_LICENSE("Dual BSD/GPL");
notifier_chain.h
#ifndef _NOTIFIER_CHAIN_H_
#define _NOTIFIER_CHAIN_H_
extern int register_test_notifier(struct notifier_block *nb);
extern int unregister_test_notifier(struct notifier_block *nb);
extern int test_notifier_call_chain(unsigned long val);
#endif
发信息producer.c
#include <linux/module.h>
#include <linux/delay.h>
#include "notifier_chain.h"
static int producer_init(void)
{
printk(KERN_INFO "%s\n",__FUNCTION__);
test_notifier_call_chain(1);
msleep(1000);
test_notifier_call_chain(1000);
return 0;
}
static void producer_exit(void)
{
printk(KERN_INFO "%s\n",__FUNCTION__);
}
module_init(producer_init);
module_exit(producer_exit);
MODULE_LICENSE("Dual BSD/GPL");
接收信息consumer.c
#include <linux/module.h>
#include "notifier_chain.h"
static int test_notify(struct notifier_block *self, unsigned long action, void *dev)
{
switch (action) {
case 1:
printk("action=%ld\n",action);
break;
case 1000:
printk("action=%ld\n",action);
break;
}
return NOTIFY_OK;
}
static struct notifier_block test_nb = {
.notifier_call = test_notify,
};
static int consumer_init(void)
{
printk(KERN_INFO "%s\n",__FUNCTION__);
register_test_notifier(&test_nb);
return 0;
}
static void consumer_exit(void)
{
printk(KERN_INFO "%s\n",__FUNCTION__);
unregister_test_notifier(&test_nb);
}
module_init(consumer_init);
module_exit(consumer_exit);
MODULE_LICENSE("Dual BSD/GPL");
相应的Makefile为
ifeq ($(KERNELRELEASE),)
KERNELDIR_OUT ?= /home/w/M8974AAAAANLYD4275/out/target/product/msm8974/obj/KERNEL_OBJ
DBG_CROSS_COMPILE ?= /home/w/M8974AAAAANLYD4275/prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-
PWD :=$(shell pwd)
modules:
$(MAKE) -C $(KERNELDIR_OUT) M=$(PWD) ARCH=arm CROSS_COMPILE=$(DBG_CROSS_COMPILE) modules
modules_install:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions modules.order Module.symvers app
.PHONY: modules modules_install clean
else
obj-m+= notifier_chain.o
obj-m+= consumer.o
obj-m+= producer.o
endif
先insmod notifier_chain.ko,consumer.ko,再insmod producer.ko,就可从打印信息中看到producer发给consumer的信息了。