Re: [PATCH 01/13] seqnum_ops: Introduce Sequence Number Ops

From: Shuah Khan
Date: Wed Nov 11 2020 - 13:28:19 EST


On 11/11/20 10:50 AM, Peter Zijlstra wrote:
On Wed, Nov 11, 2020 at 10:34:05AM -0700, Shuah Khan wrote:

Not sure what to make of the 6080 atomic_read()s and 3413
atomic_inc()s, some of which might be assuming uniqueness
guarantee.

Well, clearly you just did: git grep atimic_{read,inc}() | wc -l and
didn't look at the usage. Equally clearly there can be bugs. Also
evidently much of those are not in fact sequence numbers.


Looking at the usage and classifying which usages are sequence
numbers is part of may audit and we are covered. Your explanation
and this discussion helps with do a better audit of these usages.

All I'm saying is that if you want a sequence number, inc_return (or
fetch_inc) is the only sane option.


Cool.

thanks,
-- Shuah