From: Andrew Morton <akpm@linux-foundation.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Minfei Huang <mhuang@redhat.com>,
rob.jones@codethink.co.uk, amhyung@kernel.org,
linux-kernel@vger.kernel.org, Minfei Huang <mnfhuang@gmail.com>
Subject: Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to simplify the code
Date: Wed, 15 Jul 2015 13:31:26 -0700 [thread overview]
Message-ID: <20150715133126.c13ff1e75bf36eb0a85dcb3f@linux-foundation.org> (raw)
In-Reply-To: <87twt676fz.fsf@rustcorp.com.au>
On Wed, 15 Jul 2015 07:22:32 +0930 Rusty Russell <rusty@rustcorp.com.au> wrote:
> Minfei Huang <mhuang@redhat.com> writes:
> > From: Minfei Huang <mnfhuang@gmail.com>
> >
> > It is not elegance, if we use function directly as the argument, like
> > following:
> >
> > bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
> > struct module *owner,
> > void *data), void *data);
> >
> > Here introduce a type defined function find_symbol_in_section_t. Now
> > we can use these type defined function directly, if we want to pass
> > the function as the argument.
> >
> > bool each_symbol_section(find_symbol_in_section_t fn, void *data);
>
> I disagree.
>
> It's shorter, but it's less clear. typedefs on functions are not very
> useful:
> 1) They require readers to look in two places to see how to use the
> function (ie each_symbol_section).
> 2) They can't use the typedef to declare their function, since that
> doesn't work in C.
>
> If the function were being used many times, it makes sense. But
> it's only used twice, once static inside module.c.
>
Using a foo_t typedef for a function callback is a common pattern.
It's (almost) the only approved use of typedefs. The usage is
widespread enough that when one sees a foo_t type, one says "ahah,
that's a function pointer".
Sorry, but I don't think "Rusty doesn't like it" is a good reason for
the module code to be different. All of us dislike some aspects of
kernel coding practices, but we go along because consistency is more
important.
next prev parent reply other threads:[~2015-07-15 20:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-14 6:59 [PATCH 0/2] Using function type to cleanup the function parament Minfei Huang
2015-07-14 6:59 ` [PATCH 1/2] Define find_symbol_in_section_t as function type to simplify the code Minfei Huang
2015-07-14 7:04 ` Minfei Huang
2015-07-14 21:52 ` Rusty Russell
2015-07-15 2:11 ` Minfei Huang
2015-07-15 20:31 ` Andrew Morton [this message]
2015-07-16 11:29 ` Rusty Russell
2015-07-14 6:59 ` [PATCH 2/2] Define kallsyms_cmp_symbol_t " Minfei Huang
2015-07-14 7:05 ` Minfei Huang
2015-07-14 7:06 ` [PATCH 0/2] Using function type to cleanup the function parament Minfei Huang
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