Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1185031

Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to simplify the code

Show all headers | View raw

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.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to simplify the code Rusty Russell <rusty@rustcorp.com.au> - 2015-07-15 02:50 +0200
  Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to  simplify the code Minfei Huang <mhuang@redhat.com> - 2015-07-15 04:10 +0200
  Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to  simplify the code Andrew Morton <akpm@linux-foundation.org> - 2015-07-15 22:40 +0200
    Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to simplify the code Rusty Russell <rusty@rustcorp.com.au> - 2015-07-16 13:40 +0200

csiph-web