Re: Complaint about return code convention in queue_work() etc.

From: Alexey Dobriyan
Date: Fri Aug 18 2006 - 19:26:49 EST

On Fri, Aug 18, 2006 at 05:43:18PM -0400, Jeff Garzik wrote:
> Alan Stern wrote:
> >I'd like to lodge a bitter complaint about the return codes used by
> >queue_work() and related functions:
> >
> > Why do the damn things return 0 for error and 1 for success???
> > Why don't they use negative error codes for failure, like
> > everything else in the kernel?!!
> It's a standard programming idiom: return false (0) for failure, true
> (non-zero) for success. Boolean.

There are at least 3 idioms:

1) return 0 on success, -E on fail¹.

rv = foo();
if (rv < 0)

2) return 1 on YES, 0 on NO.
3) return valid pointer on OK, NULL on fail.

p = kmalloc();
if (!p)

#2 should only be used if condition in question is spelled nice:

if (license_is_gpl_compatible())

The question is into which category queue_work() fails.

> Certainly the kernel often uses the -errno convention, but it's not a rule.

¹ BSD returns E* where E* is negative and thus avoids "return E*;" bugs (where E
is positive).

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