问sysfs文件上来自用户空间的poll()和内核空间中的sysfs_notify()将无法工作

EN

// [...]

static struct kobject *gpio; // dir /sys/kernel/gpio

static ssize_t gpio17s_show(struct kobject *kobj,struct kobj_attribute
            *attr,char *buf)
{
    return sprintf(buf,"%li",sec1);
}

static ssize_t gpio17s_store(struct kobject *kobj,struct kobj_attribute
            *attr,const char *buf,size_t count)
{
    sscanf(buf,"%li",&sec1);
    return count;
}

}

// [...] (two more files)

static ssize_t gpio26n_show(struct kobject *kobj,struct kobj_attribute
            *attr,char *buf)
{
    sysfs_notify(gpio,NULL,"gpio26n"); // Is this the right place, the right invocation????
    // I saw this already in isr, but i believe this is not a good idea....
    // Has it perhaps to be in module_init function???
    // First arg('gpio') is kobject of the dir containing files(attributes)..
    // This can not be right in my mind, but how do I find the right kobj??
    // The third param 'gpio26n' if the file, on which I'm polling.

    return sprintf(buf,"%li",nsec2);
}

static ssize_t gpio26n_store(struct kobject *kobj,struct kobj_attribute
            *attr,const char *buf,size_t count)
{
    sscanf(buf,"%li",&nsec2);
    return count;
}

static int cleanup(int value,int ret) {

    switch(value) {
        case 5:
            free_irq(speed_irq2,NULL);
        case 4:
            free_irq(speed_irq1,NULL);
        case 3:
            gpio_free(PIN2);
        case 2:
            gpio_free(PIN1);
        case 1:
            kobject_put(gpio);
    }

    return ret;
}

static irqreturn_t speed_isr(int irq, void *data) {

    if(irq==speed_irq1) {
        getrawmonotonic(&ts1);
        sec1=ts1.tv_sec;
        nsec1=ts1.tv_nsec;
    }

    if(irq==speed_irq2) {
        getrawmonotonic(&ts2);
        sec2=ts2.tv_sec;
        nsec2=ts2.tv_nsec;
    }

    return IRQ_HANDLED;
}

static struct kobj_attribute gpio17s_attr = __ATTR(gpio17s,0644,
        gpio17s_show,gpio17s_store);
static struct kobj_attribute gpio26n_attr = __ATTR(gpio26n,0644,
        gpio26n_show,gpio26n_store);

static int  __init d_init(void) {

    int ret=0;

    printk(KERN_INFO "Module successfully loaded...");

    gpio=kobject_create_and_add("gpio",kernel_kobj);
    if(!gpio) {
        printk(KERN_ERR "Failed to create 'gpio'");
        return -ENOMEM;
    }

    ret=sysfs_create_file(gpio,&gpio17s_attr.attr);
    if(ret) {
        printk(KERN_ERR "Failed to create file 'gpio17s'");
        return cleanup(1,2);
    }

    // [...] (two more files)

    ret=sysfs_create_file(gpio,&gpio26n_attr.attr);
    if(ret) {
        printk(KERN_ERR "Failed to create file 'gpio26n'");
        return cleanup(1,5);
    }

    ret=gpio_request(PIN1,"gpio 17");
    if(ret) {
        printk(KERN_ERR "Failed to request 'gpio17'");
        return cleanup(1,6);
    }

    ret=gpio_request(PIN2,"gpio 26");
    if(ret) {
        printk(KERN_ERR "Failed to request 'gpio26'");
        return cleanup(2,7);
    }

    ret=gpio_to_irq(PIN1);
    if(ret<0) {
        printk(KERN_ERR "Unable to get irq for pin 17");
        return cleanup(3,8);
    }

    speed_irq1=ret;

    ret=gpio_to_irq(PIN2);
    if(ret<0) {
        printk(KERN_ERR "Unable to get irq for pin 26");
        return cleanup(3,9);
    }

    speed_irq2=ret;

    ret=request_irq(speed_irq1,speed_isr,IRQF_TRIGGER_RISING,
            "Speed trigger 17",NULL);
    if(ret) {
        printk(KERN_ERR "Unable to request irq for pin 17");
        return cleanup(3,10);
    }

    ret=request_irq(speed_irq2,speed_isr,IRQF_TRIGGER_RISING,
            "Speed trigger 26",NULL);
    if(ret) {
        printk(KERN_ERR "Unable to request irq for pin 26");
        return cleanup(4,10);
    }

    return 0;
}

static void __exit d_exit(void) {
// [...]

// [...]

int main() {

    int           f      ;
    char          buf[16];
    struct pollfd pfd    ;

    while(1) {
        memset(buf,0,sizeof(buf));

        if((f=open("/sys/kernel/gpio/gpio26n",O_RDONLY)) <0) {
            fprintf(stderr,"Failed to open sysfs file\n");
            exit(1);
        }

        if((lseek(f,0L,SEEK_SET)) <0) {
            fprintf(stderr,"Failed to set pointer\n");
            exit(2);
        }


        if((read(f,buf,1)) <0) {
            fprintf(stderr,"Failed to read from file\n");
            exit(3);
        }

        pfd.fd     = f      ;
        pfd.events = POLLPRI;

        poll(&pfd,1,-1); // This should block until value has changed....
        close(f);


        // fopen, read new value etc.
        // [...]

        // Do some stuff, calculate speed, etc
    }
}