linux-kernel - Re: [PATCH v2] Documentation: livepatch: Add livepatch API page

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Date:   Thu, 16 Dec 2021 07:00:38 -0800
From:   David Vernet <void@...ifault.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, jpoimboe@...hat.com, jikos@...nel.org,
        mbenes@...e.cz, joe.lawrence@...hat.com, corbet@....net
Subject: Re: [PATCH v2] Documentation: livepatch: Add livepatch API page

Petr Mladek <pmladek@...e.com> wrote on Thu [2021-Dec-16 10:57:04 +0100]:

> This change is not good. The function releases all existing shadow
> variables with the given @id for any @obj. And it is not longer clear.

Good point. I'll address that in v3.

> I guess that the primary motivation was to remove  "Inline emphasis
> start-string without end string" mentioned in the commit message.

Yes, this was the primary and only motivation. <*, id> is much clearer and I'm
with you on finding a better alternative.

> A solution would be replace '*' with something else, for example, < , id>.

I think this is better than just obj, but in my opinion this may be confusing
for readers and look like a typo. I think I prefer your second suggestion,
though obj really makes more sense in the case where we're actually passing an
@obj to the function. I'll probably (deservedly?) get lambasted for suggesting
this, but what about taking a page out of rust's book and doing something like
this:

  * klp_shadow_free_all() - detach and free all <_, id> shadow variables
  *		with the given @id.

to indicate that in this case we don't care about the obj. Even for a reader
unfamiliar with rust, hopefully it would get the point across.

> Another solution would be to describe it another way, for example:
> 
>  * klp_shadow_free_all() - detach and free all <obj, id> shadow variables
>  *		with the given @id.

I'm fine with this as well. Let me know what you think about <_, id> vs. what
you suggested, and I'll send out the v3 patch with your preference.

> BTW: There is likely the same problem in Documentation/livepatch/shadow-vars.rst.
>      I see <*, id> there as well.

Indeed you're correct. There's no warning in the build system because there
happen to be two <*, id> ... <*, id> in a row, so rst happily italicizes what's
between them without question. I'll fix this in the v3 of the patch as well.

> Otherwise, the patch looks fine to me.

Thanks for taking a look and for the helpful suggestions.

- David