svn commit: r230628 - head/sys/sparc64/include

[Julian Elischer]

On 1/28/12 12:23 AM, Bruce Evans wrote:
> On Fri, 27 Jan 2012, Marius Strobl wrote:
>
>> Log:
>>  Mark cpu_{halt,reset}() as __dead2 as appropriate.
>>
>> Modified:
>>  head/sys/sparc64/include/cpu.h
>>
>> Modified: head/sys/sparc64/include/cpu.h
>> ============================================================================== 
>>
>> --- head/sys/sparc64/include/cpu.h    Fri Jan 27 21:52:59 2012    
>> (r230627)
>> +++ head/sys/sparc64/include/cpu.h    Fri Jan 27 22:04:43 2012    
>> (r230628)
>> @@ -53,8 +53,8 @@ extern    char btext[];
>> extern    char etext[];
>>
>> void    cheetah_init(u_int cpu_impl);
>> -void    cpu_halt(void);
>> -void    cpu_reset(void);
>> +void    cpu_halt(void) __dead2;
>> +void    cpu_reset(void) __dead2;
>> void    fork_trampoline(void);
>> void    swi_vm(void *v);
>> void    zeus_init(u_int cpu_impl);
>
> This reminds me that these functions and many others shouldn't be
> in <machine/cpu.h> since they necessarily have a MI interface (so
> that MI code can call them).  A few interfaces in <machine/cpu.h>
> need to be there so that the can be inlines or macros, but most
> don't.  Especially these 2.  Since they are extremely non-time-
> critical and not likely to be magical, they can be implemented as
> a wrapper extern function even if the MD code prefers to use an
> in inline or macro.  Duplicating these 2 in ${N_ARCH} cpu.h files
> mainly allows some of the files to forget to declare them as
> __dead2.
>
> I put these in <sys/systm.h> and didn't forget __dead2 for them.
> systm.h already has prototypes for 11 functions named cpu_*.  These
> are unsorted of course.  It also has prototypes for a few functions
> that are misnamed (without a cpu_ as a prefix, or perhaps without
> cpu_ or cpu at all) so that they are naturally unsorted and hard to
> find.
>
> No MD declaration of these 2 in -current except the above has the
> __dead2's.  IIRC, I noticed that __dead2 was missing for them from
> the style bug that code after calls to them has /* NOTREACHED */
> comments (shutdown_halt() still does, except in my version).
> __dead2 should have made most of these comments go away 15-20 years
> ago.
>
> A more important "cpu_" function whose comments annoy me is
> cpu_throw().  This has always been declared in an MI file
> (<sys/proc.h>, which shows that we can't expect all these functions
> to be declared in <sys/systm.h> if they are MI).  Calls to
> cpu_throw() have the unnecessary comments /* doesn't return */ in
> 2 places (lint won't understand these, so if you are going to
> comment on the obvious then it should be /* NOTREACHED */), and a
> bogus "teapot" panic and a /* NOTREACHED */ comment in another
> place.  The panic is so bogus that gcc removes it (as allowed by
> cpu_throw() being declared __dead2).  The first 2 places are
> sched_throw() in 2 schedulers.  This can't return, but isn't
> declared as __dead2.  The other place is thread_exit().  This is
> one of very few extern functions that is declared as __dead2.
>
> Bruce
>
Bruce these comments are valid.
please make use of your commit bit and make the appropriate changes!