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Date:      Sat, 15 Dec 2012 05:29:10 -0800
From:      Alfred Perlstein <bright@mu.org>
To:        Gleb Smirnoff <glebius@FreeBSD.org>
Cc:        Adrian Chadd <adrian@FreeBSD.org>, src-committers@FreeBSD.org, John Baldwin <jhb@FreeBSD.org>, svn-src-all@FreeBSD.org, Andriy Gapon <avg@FreeBSD.org>, Navdeep Parhar <np@FreeBSD.org>, svn-src-head@FreeBSD.org
Subject:   Re: svn commit: r244112 - head/sys/kern
Message-ID:  <50CC7B26.5000708@mu.org>
In-Reply-To: <20121215130149.GB94420@FreeBSD.org>
References:  <201212110708.qBB78EWx025288@svn.freebsd.org> <50C9271C.70803@mu.org> <20121213090215.GP97487@FreeBSD.org> <201212141149.07671.jhb@freebsd.org> <alpine.BSF.2.00.1212150010160.54345@fledge.watson.org> <50CBC285.7060307@mu.org> <20121215161414.V1029@besplex.bde.org> <50CC6E8D.6040707@mu.org> <20121215130149.GB94420@FreeBSD.org>

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On 12/15/12 5:01 AM, Gleb Smirnoff wrote:
> On Sat, Dec 15, 2012 at 04:35:25AM -0800, Alfred Perlstein wrote:
> A> People keep beating this drum "all invariants/panics are there for a
> A> reason", no, some happen to be bugs, and when I'm shipping code to a
> A> customer, I may need to skip one of these buggy assertions.
>
> Yes, if you know any buggy assertions, please remove them from FreeBSD tree.
>
> A> Some people have responded to this by saying "alfred show me the buggy
> A> assertions" to which my response is two fold "firstly, you're calling me
> A> a liar which I do not appreciate, second prove to me that all the 1000s
> A> of asserts have zero bugs and are not overly zealous about calling panic."
>
> We are not going to prove that. If you claim that some assertion is buggy,
> you prove that it is buggy and happily remove it from source tree. Noone
> is going to spend time proving you that 1000s of assertions are not buggy.
>
> Home reading for you:
>
> http://en.wikipedia.org/wiki/Russell%27s_teapot
>
Here is some reading for you:

------------------------------------------------------------------------
r244044 | adrian | 2012-12-08 17:08:44 -0800 (Sat, 08 Dec 2012) | 10 lines

Don't panic if the stageq here is empty; just fall through with NULL
pointers and leave the stage queue flush routine to just do nothing
(since both head and tail here will be NULL.)

This should quieten the "stageq empty" panic where the stageq itself
is empty, but it won't fix the second KASSERT() here "staging queue empty"
as that's likely a different underlying problem.

PR:             kern/174283

------------------------------------------------------------------------

svn diff -r244043:244044

This kassert bug has existed since rev 190579:
r190579 | sam | 2009-03-30 14:53:27 -0700 (Mon, 30 Mar 2009) | 25 lines


thanks,
-Alfred



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