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Date: Tue, 7 Aug 2001 11:09:16 -0600
Message-Id: <200108071709.f77H9GD05198@vindaloo.ras.ucalgary.ca>
From: Richard Gooch <rgooch@ras.ucalgary.ca>
To: Anton Altaparmakov <aia21@cus.cam.ac.uk>
Cc: Alexander Viro <viro@math.psu.edu>,
        Linus Torvalds <torvalds@transmeta.com>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] one of $BIGNUM devfs races
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Anton Altaparmakov writes:
> If you are introducing a spinlock for the sole purpose of protecting
> a counter, I would suggest to drop the spinlock, make the counter an
> atomic_t and just use atomic operations on it. That should be both
> faster and generate shorter code.

Firstly, I don't see an atomic_get_and_inc(). Sure, I can atomically
increment, and I can atomically read. But I can't read and increment
atomically.

Secondly, the range is 24 bits. While 24 bits is "probably enough",
I'd prefer not to waste bits.

Finally, a spinlock is less code (0) and faster on UP.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
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