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SubjectRe: Must check what?
On Wed, 4 Oct 2006 13:25:37 -0600
Matthew Wilcox <matthew@wil.cx> wrote:

> On Wed, Oct 04, 2006 at 12:02:42PM -0700, Andrew Morton wrote:
> > I blame kernel-doc. It should have a slot for documenting the return value,
> > but it doesn't, so nobody documents return values.
>
> There's also the question about where the documentation should go. By
> the function prototype in the header? That's the easy place for people
> using the function to find it. By the code? That's the place where it
> stands the most chance (about 10%) of somebody bothering to update it
> when they change the code.

yes, by the code, if it's C. In .h if it's C++.

> > It should have a slot for documenting caller-provided locking requirements
> > too. And for permissible calling-contexts. They're all part of the
> > caller-provided environment, and these two tend to be a heck of a lot more
> > subtle than the function's formal arguments.
>
> Indeed. And reference count assumptions. It's almost like we want a
> pre-condition assertion ...

We have might_sleep(), assert_spin_locked(), BUG_ON(!irqs_disabled()), etc.

I like assertions personally. If we had something like:

void foo(args)
{
locals;

assert_irqs_enabled();
assert_spin_locked(some_lock);
assert_in_atomic();
assert_mutex_locked(some_mutex);

then we get documentation which is (optionally) checked at runtime - best
of both worlds. Better than doing it in kernel-doc. Automatically
self-updating (otherwise kernels go BUG).

But we'd need to sell the idea ;)

And we still need to document those return values in English.

(Or we do

return assert_zero_or_errno(ret);

which is a bit ug, but gets us there)
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