Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH 1/7] General notification queue with user mmap()'able ring buffer | Date | Wed, 29 May 2019 22:02:43 +0100 |
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Jann Horn <jannh@google.com> wrote:
> Does this mean that refcount_read() isn't sufficient for what you want > to do with tracing (because for some reason you actually need to know > the values atomically at the time of increment/decrement)?
Correct. There's a gap and if an interrupt or something occurs, it's sufficiently big for the refcount trace to go weird.
I've seen it in afs/rxrpc where the incoming network packets that are part of the rxrpc call flow disrupt the refcounts noted in trace lines.
David
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