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Date: Wed, 14 Sep 2011 21:15:38 +0800
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From: Adrian Chadd <adrian@freebsd.org>
To: John Baldwin <jhb@freebsd.org>
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Cc: freebsd-net@freebsd.org, Ryan Stone <rysto32@gmail.com>,
	Jack Vogel <jfvogel@gmail.com>, Arnaud Lacombe <lacombar@gmail.com>
Subject: Re: FreeBSD 7-STABLE mbuf corruption
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On 14 September 2011 19:40, John Baldwin <jhb@freebsd.org> wrote:

> You should probably commit that. =A0I wonder if it should be a KASSERT() =
also so
> that it outright panics on a kernel with INVARIANTS enabled so developers=
 will
> go fix their code as it seems to me to likely be a bug to enqueue a task =
that
> many times.

Or maybe warn? If it's used per-interrupt (like say it is under ath,
but for a 10GE NIC doing a high packet rate) then you may end up
enqueuing the taskqueue quite often before it next gets a chance to
run. Otherwise the code will have to add some more locking and
tracking of its own to only enqueue the task once.

As I said, I'm just worried that some of the taskqueue users are doing
some kind of poor mans refcounting where n(taskqueue_enqueue)
references has to equal the npending field in the taskqueue callback.


Adrian