Messages in this thread |  | | | From | David Howells <> | | Subject | Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation | | Date | Tue, 13 Dec 2005 13:32:39 +0000 |
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Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > (5) Redirects the following to apply to the new mutexes rather than the > > traditional semaphores: > > > > down() > ... > > And you've audited every occurence ?
Outside of the arch directories, yes; but I don't know that I've made the correct decision in 100% of the cases.
I've changed some of the uses into completions, and found about a dozen or so uses of counting semaphores; but the vast majority of occurrences seem to be wanting mutex behaviour.
> It seems to me it would be far far saner to define something like > > sleep_lock(&foo) > sleep_unlock(&foo) > sleep_trylock(&foo)
Which would be a _lot_ more work. It would involve about ten times as many changes, I think, and thus be more prone to errors.
> Its then obvious what it does, you don't randomly break other drivers you've > not reviewed and the interface is intuitive rather than obfuscated.
I've attempted to review everything in 2.6.15-rc5 outside of most of the archs. I can't easily modify any driver not contained in that tarball, but at least the compiler will barf and force a review.
> It won't take long for people to then change the name of the performance > critical cases and the others will catch up in time.
It took about ten hours to go through the declarations of struct semaphore and review them; I hate to think how long it'd take to go through all the ups and downs too.
> It also saves breaking every piece of out of tree kernel code for now > good reason.
But my patch means the changes required are in the most cases minimal: just changing struct semaphore to struct mutex is sufficient for the vast majority of cases.
Your way requires a lot more work, both in the tree and out of it.
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