Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 15 Jul 2015 13:31:26 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 1/2] Define find_symbol_in_section_t as function type to simplify the code |
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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.
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