Is `IS_ERR_VALUE` indicates that the return value is invalid?

Anand Moon moon.linux at
Wed Nov 20 05:12:06 EST 2013


Please find the example to user file open in kernel below.  source file  #linux/sound/sound_firmware.c

struct file* filp;
filp = filp_open(fn, 0, 0);
if (IS_ERR(filp))
        printk(KERN_INFO "Unable to load '%s'.\n", fn);
        return 0;

IS_ERR expand to below example. 

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
static inline long __must_check IS_ERR(__force const void *ptr)
    return IS_ERR_VALUE((unsigned long)ptr);

-Anand Moon

On Thursday, November 7, 2013 11:24 AM, 乃宏周 <naive231 at> wrote:
In kernel source, `IS_ERR_VALUE` is defined:

#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

It's usage can be realized literally, but definition is not.
Can I use this macro to determines the kernel API's result is valid?

if (IS_ERR_VALUE(filp_open(device)))


Kernelnewbies mailing list
Kernelnewbies at
-------------- next part --------------
An HTML attachment was scrubbed...

More information about the Kernelnewbies mailing list