linux内核常用宏实例【一】

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linux内核常用宏实例【一】

/* Force a compilation error if condition is true */#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])

如果条件为真则引起一个编译时错误。

使用实例：
static int __init spidev_init(void){ int status; /* Claim our 256 reserved device numbers. Then register a class * that will key udev/mdev to add/remove /dev nodes. Last, register * the driver which manages those device numbers. */ BUILD_BUG_ON(N_SPI_MINORS > 256);//如果条件为真，则引起一个编译错误 status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);//注册驱动 if(status < 0) return status; spidev_class = class_create(THIS_MODULE, "spidev");//创建设备文件 if(IS_ERR(spidev_class)) { unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); return PTR_ERR(spidev_class); } status = spi_register_driver(&spidev_spi); if(status < 0) { class_destroy(spidev_class); unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); } return status;}