Date: Sat, 18 May 2002 19:52:36 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Terry Lambert <tlambert2@mindspring.com> Cc: net@FreeBSD.org, current@FreeBSD.org, "Kenneth D. Merry" <ken@kdm.org>, Alfred Perlstein <bright@mu.org> Subject: Re: new zero copy sockets patches available Message-ID: <XFMail.20020518195236.jhb@FreeBSD.org> In-Reply-To: <3CE6E6A2.4A42228B@mindspring.com>
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On 18-May-2002 Terry Lambert wrote:
> John Baldwin wrote:
>> On 18-May-2002 Terry Lambert wrote:
>> > John Baldwin wrote:
>> >> > God, it's annoying that a statically declared mutex is not
>> >> > defacto initialized.
>> >>
>> >> Is it in solaris?
>> >
>> > It isn't in FreeBSD because of the need to link mutex'es into
>> > the "witness protection program". 8-).
>>
>> Actually, there is more to it than that. Or at least, there will be
>> when turnstiles are added (turnstiles require some function callouts
>> to work properly).
>
> It's the function callouts that are the problem. 8-(.
Unfortunately there aren't easy solutions to this. Even solaris 7
uses callouts. We would use fewer of them at least.
>> > MUTEX_DECLARE(mutex_name).
>>
>> Umm, yes, like MTX_SYSINIT(). :)
>
> No. An MTX_SYSINIT() that wrapped a declaration and a SYSINIT()
> would als imply the definition of an static function to do the
> initialization, that then got called by the SYSINIT() itself.
This is a false implication.
> This is actually what I was saying was bad: a static function
> per mutex declaration.
Umm, no, there is _one_ global function that we call. Why not check
the actual code?
> So, among other things, you want to use the same initializer function
> instance for all statically declared mutexes.
Um, we already do this.
> So you have to use something other than a SYSINIT() for the declarations,
> but you could use *one SYSINIT()* to do the pre-use initialization of
> *all* declarations.
Why don't you read the code?
Here, I'll quote it for you:
struct mtx_args {
struct mtx *ma_mtx;
const char *ma_desc;
int ma_opts;
};
#define MTX_SYSINIT(name, mtx, desc, opts) \
static struct mtx_args name##_args = { \
mtx, \
desc, \
opts \
}; \
SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
mtx_sysinit, &name##_args)
Note no static function, instead we use the global function mtx_sysinit()
in kern_mutex.c:
/*
* General init routine used by the MTX_SYSINIT() macro.
*/
void
mtx_sysinit(void *arg)
{
struct mtx_args *margs = arg;
mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
}
--
John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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