On Tue, 6 Jan 2004, Duncan Sands wrote:
> Hi Alan, if you check out the patch you will see that I concluded that all the
> tests in question fell into case (2) and removed them. I think we both
> agree about case (2). I guess there is some confusion about case (1).
> If the result of not testing is that the driver oopses (and maybe can't
> be used anymore), but the core is left in an OK state then that is case (2)
> and not case (1). Case (1) is when the core will, for example, get into
> an inconsistent state if the check is omitted. In that case testing is
> necessary. If the test fails, a BUG may be quite appropriate.
You mean, case (1) is when the core will get into an inconsistent state
without creating any visible indications (like an oops)? Then I agree
that a BUG may be appropriate. If the core would oops without the test
then a BUG won't make any difference.
> Remember,
> I was arguing against Dave's code bloat argument, and pointing out
> when tests should not be removed (and maybe improved).
I don't recall the context of the tests you were discussing before. But
I'm seen too many cases of code like this (from core/hcd.c:hcd_alloc_dev):
if (!udev || udev->hcpriv)
return -EINVAL;
if (!udev->bus || !udev->bus->hcpriv)
return -ENODEV;
with no explanation or comment about whether those tests are _ever_
supposed to fail, or what it would mean if they did.
And remember also, drivers are part of the kernel. They're _supposed_ to
be trustworthy. If the core tries to second-guess everything they do, it
will never get any of its own work done.
Alan Stern
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