Re: [PATCH v2] KEYS: trusted: Remove redundant static calls usage

[Jarkko Sakkinen <jarkko@kernel.org>]

On Tue, 2023-10-10 at 11:28 -0700, Linus Torvalds wrote:
> On Thu, 5 Oct 2023 at 22:18, Sumit Garg <sumit.garg@linaro.org> wrote:
> > 
> > Static calls invocations aren't well supported from module __init and
> > __exit functions. Especially the static call from cleanup_trusted() led
> > to a crash on x86 kernel with CONFIG_DEBUG_VIRTUAL=y.
> > 
> > However, the usage of static call invocations for trusted_key_init()
> > and trusted_key_exit() don't add any value from either a performance or
> > security perspective. Hence switch to use indirect function calls instead.
> 
> I applied this patch to my tree, since it is a fix for the issue, and
> doesn't change any logic otherwise.
> 
> However, I do note that the code logic is completely broken. It was
> broken before too, and apparently causes no problems, but it's still
> wrong.
> 
> That's a separate issue, and would want a separate patch, but since I
> noticed it when applying this one, I'm replying here:
> 
> > +               trusted_key_exit = trusted_key_sources[i].ops->exit;
> >                 migratable = trusted_key_sources[i].ops->migratable;
> > 
> > -               ret = static_call(trusted_key_init)();
> > +               ret = trusted_key_sources[i].ops->init();
> >                 if (!ret)
> >                         break;
> 
> Note how this sets "trusted_key_exit" even when the ->init() function fails.

Sumit, can you remind me why this continues *on any failure*?

E.g. something like this would make more sense to me:

		ret = trusted_key_sources[i].ops->init();
		if (!ret) {
			static_call_update(trusted_key_seal, trusted_key_sources[i].ops->seal);
			static_call_update(trusted_key_unseal, trusted_key_sources[i].ops->unseal);
			static_call_update(trusted_key_get_random, get_random);
			static_call_update(trusted_key_exit, trusted_key_sources[i].ops->exit);
			migratable = trusted_key_sources[i].ops->migratable;
			break;
		}

		if (ret != -ENODEV)
			break;
`
BR, Jarkko