Re: Top kernel oopses/warnings this week

Linus Torvalds
2007-12-18T00:32:27Z

On Mon, 17 Dec 2007, Arjan van de Ven wrote:
>
> +char *get_boot_uuid(void)
> +{
> + static char target[38];
> + unsigned char *uuid;
> +
> + if (sysctl_bootid[8] == 0)
> + generate_random_uuid(sysctl_bootid);
> + /* sysctl_bootid is signed, to print we need unsigned .. */
> + uuid = sysctl_bootid;
> +
> + if (target[0] == 0) {
> + sprintf(target, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
> + "%02x%02x%02x%02x%02x%02x",

Why isn't *everything* inside that "if (target[0] == 0" check?

IOW, that function should look something like

const char *get_boot_uuid(void)
{
static char target[38];

if (!target[0])
fill_boot_uid(target)
return target;
}

which also allows you to clean it up a bit.

I'd _also_ suggest that you'd actually try to avoid that horrid sequence
of "%02x..", and instead just make sure that sysctl_bootid[] is 4-byte
aligned, and then you can do

sprintf("%08x-%04x-%04x-%04x-%04x%08x",
ntohl(0[(u32 *)uuid]),
ntohs(2[(u16 *)uuid]),
ntohs(3[(u16 *)uuid]),
ntohs(4[(u16 *)uuid]),
ntohs(5[(u16 *)uuid]),
ntohl(3[(u32 *)uuid]));

which also gets bonus points for being totally unreadable, and thus 100%
in the spirit of uuid's.

Linus