Re: question: spinlocks and userspace.

Stephen C. Tweedie (sct@redhat.com)
Wed, 10 Nov 1999 21:54:13 +0000 (GMT)


Hi,

On Wed, 10 Nov 1999 16:17:59 +0000 (GMT), Tigran Aivazian
<tigran@sco.COM> said:

>> Alternatively, can you make do with a semaphore?

> I tried - didn't work. If you are curious, have a look at my
> semaphore-based implementation (with deadlock)

> http://www.ocston.org/~tigran/patches/modsem-2.3.27-p5.patch

You still have to be careful to get the locking right. :) Remember, you
can't arbitrarily replace shared spinlocks with semaphores: shared
spinlocks will still work if you take them recursively, semaphores
won't.

> Silly question - do the interrupts ever do request_module()? If not, then
> we can forget about the above two paragraphs?

Given that it calls waitpid(), they had better not. :) Sleeping in an
interrupt is about the most illegal thing a kernel function can do!

--Stephen

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/