svn commit: r283088 - head/sys/ddb

[John Baldwin]

On Tuesday, May 19, 2015 12:28:05 AM Pedro Giffuni wrote:
> >>>> Modified: head/sys/ddb/db_break.c
> >>>> ==============================================================================
> >>>> --- head/sys/ddb/db_break.c	Mon May 18 22:14:06 2015	(r283087)
> >>>> +++ head/sys/ddb/db_break.c	Mon May 18 22:27:46 2015	(r283088)
> >>>> @@ -155,12 +155,12 @@ db_find_breakpoint_here(db_addr_t addr)
> >>>> 	return db_find_breakpoint(db_map_addr(addr), addr);
> >>>> }
> >>>> 
> >>>> -static boolean_t	db_breakpoints_inserted = TRUE;
> >>>> +static boolean_t	db_breakpoints_inserted = true;
> >>> 
> >>> This code hasn't been churned to use the boolean type.  It still uses
> >>> boolean_t, which is plain int.  TRUE and FALSE go with this type.  true
> >>> and false go with the boolean type.  This probably makes no difference,
> >>> because TRUE happens to be implemented with the same value as true and
> >>> there are lots of implicit versions between the types.
> >> 
> >> Yes, I noticed the return types are still ints. It doesn’t look difficult
> >> to convert it to use a real boolean type.  In any case, I would prefer to go
> >> forward (using bool) instead of reverting this change.
> > 
> > That wuld be sideways.
> > 
> > I forgot to mention (again) in my previous reply that boolean_t is a mistake
> > by me.  KNF code doesn't even use the ! operator, but uses explicit
> > comparison with 0.  The boolean_t type and TRUE and FALSE are from Mach.
> > They were used mainly in ddb and vm, and are still almost never used in
> > kern.  I used to like typedefs and a typedef for boolean types, and didn't
> > know KNF very well, so in 1995 I moved the declaration of boolean_t from
> > Mach vm code to sys/types.h to try to popularize it.  This was a mistake.
> > Fortunately, it is still rarely used in core kernel code.
> > 
> > The boolean type is also almost never used for syscalls.  In POSIX.1-2001,
> > <stdbool.h> is inherited from C99, but is never used for any other POSIX
> > API.  Using it for syscalls would mainly cause portability problems.
> > 
> 
> OK, I do understand the kernel wants to keep the C dialect somewhat limited,
> and adding stdbool.h doesn’t buy us any type safety here.
> 
> I’ll revert the change (prob. tomorrow though).

I will disagree with Bruce a bit and put my vote in for replacing boolean_t
with bool where it is used.  I do think that logically (if not strictly) your
commit is a type mismatch as TRUE/FALSE is for boolean_t and true/false are
for bool.  I agree with Bruce that we probably don't want to use bool for
system calls.  However, I think using bool in the kernel itself is ok and that
we should replace boolean_t with bool.

-- 
John Baldwin