如何通过sysfs或proc将内核参数显示和更新

/* DEVICE_ATTR(state) clashes with dev_attr_state for sdev */
struct device_attribute dev_attr_hstate =
__ATTR(state, S_IRUGO | S_IWUSR, show_shost_state, store_shost_state);
static ssize_t
show_shost_mode(unsigned int mode, char *buf)
{
ssize_t len = 0;
if (mode & MODE_INITIATOR)
len = sprintf(buf, "%s", "Initiator");
if (mode & MODE_TARGET)
len += sprintf(buf + len, "%s%s", len ? ", " : "", "Target");
len += sprintf(buf + len, "\n");
return len;
}