Messages in this thread | | | Date | Wed, 11 Oct 2006 05:34:12 -0400 (EDT) | From | "Robert P. J. Day" <> | Subject | Re: thoughts on potential cleanup of semaphores? |
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On Tue, 10 Oct 2006, Steven Rostedt wrote:
> > On Tue, 2006-10-10 at 12:00 -0400, Robert P. J. Day wrote:
> > 1) can all instances of sema_init() in the header files be simplified > > based on the comment you can see in some of those header files? > > > > ======================== > > static inline void sema_init (struct semaphore *sem, int val) > > { > > /* > > * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); > > * > > * i'd rather use the more flexible initialization above, but sadly > > * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well. > > */ > > atomic_set(&sem->count, val); > > sem->sleepers = 0; > > init_waitqueue_head(&sem->wait); > > } > > ======================== > > > > one would think there's little value in retaining code that > > accommodates something as old as GCC 2.7.2.3, but i'm not the expert > > here. > > Well, I believe it's official, that we don't support GCC 2.7.2.3 anymore > anyway.
ok, so a patch to simplify *all* of the above implementations of sema_init() to a single call to __SEMAPHORE_INITIALIZER() would not be out of line. i'll resubmit my earlier one, making sure it's based on the latest "git pull".
> > and stepping back and looking at the bigger picture, it seems that > > the semaphore.h files across all architectures are *almost* identical, > > with a small number of differences, such as: > > All those asm statements :-)
well, ok, i worded that badly. let me try again. at least the semaphore *interfaces* across all architectures seem to be almost identical, with the exception, of course, of the inline "asm" routines. but (and i know this idea is not going *anywhere*) when a routine in a header file is defined as inline and consists of a dozen assembler statements, wouldn't it make more sense to (dons asbestos suit here) have those routines be part of the *source* file and not the header file?
i'm probably making more of this than it's worth but, as i was digging around in the semaphore implementations, it struck me that there was a lot of unnecessary duplication across the numerous semaphore.h files. is there no reasonable way to get rid of at least *some* of that?
> > p.s. trying to condense all of the separate semaphore.h files > > into a single, configurable one would also solve the problem of > > incorrect documentation in some of them that is clearly the result > > of cut-and-paste. but i'm interested in what the experts have to > > say. > > But the meat in those files are in the down and up functions. Which > are all pretty much drastically different. All you would accomplish > is some standard initialization of the structure and sema_init.
so perhaps the up and down functions represent the stuff that can be kept in arch-specific files, while the rest of semaphore.h is condensed to a single, cross-arch file. it still seems like there's lots of redundancy that can be eliminated here with very little effort.
in defense of minimalism, rday - 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/
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