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Date:      Tue, 18 Dec 2012 15:37:22 -0500
From:      John Baldwin <jhb@freebsd.org>
To:        Alfred Perlstein <bright@mu.org>
Cc:        Adrian Chadd <adrian@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, Alfred Perlstein <alfred@freebsd.org>, Andriy Gapon <avg@freebsd.org>, Gleb Smirnoff <glebius@freebsd.org>, Robert Watson <rwatson@freebsd.org>, Navdeep Parhar <np@freebsd.org>, Bruce Evans <brde@optusnet.com.au>, svn-src-head@freebsd.org
Subject:   Re: svn commit: r244112 - head/sys/kern
Message-ID:  <201212181537.23341.jhb@freebsd.org>
In-Reply-To: <50CF8CE7.4020906@mu.org>
References:  <201212110708.qBB78EWx025288@svn.freebsd.org> <201212171439.27297.jhb@freebsd.org> <50CF8CE7.4020906@mu.org>

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On Monday, December 17, 2012 4:21:43 pm Alfred Perlstein wrote:
> On 12/17/12 11:39 AM, John Baldwin wrote:
> > On Saturday, December 15, 2012 1:04:17 am Bruce Evans wrote:
> >> On Fri, 14 Dec 2012, Alfred Perlstein wrote:
> >>
> >>> On 12/14/12 4:12 PM, Robert Watson wrote:
> >>>> On Fri, 14 Dec 2012, John Baldwin wrote:
> >>>>
> >>>>> On Thursday, December 13, 2012 4:02:15 am Gleb Smirnoff wrote:
> >>>>>> On Wed, Dec 12, 2012 at 04:53:48PM -0800, Alfred Perlstein wrote: A> The
> >>>>>> problem again is that not all the KASSERTS are inviolable, if you A> want
> >>>>>> to do a project to split them, then please do, it would really be A>
> >>>>>> helpful, as for now, they are a mis-mash of death/warnings and there are
> >>>>>> A> at least three vendors who approve of this as well as 3 long term A>
> >>>>>> committers that approved my change (not including Adrian).
> >>>>>>
> >>>>>> Can you show examples of not inviolable KASSERTs?
> >>>>> There are none.  They are all assertions for a reason.  However, in my
> >> Not even one whose existence is a bug? :-)
> > They should just not exist at all then. :)  All the more reason for them to
> > panic early and often so developers will be prompted to remove them.
> >
> This is hard to explain to a customer.
> 
> customer: "So we ran your debug image and got you a panic, here is the 
> information.  So can you tell us what is the problem?"
> alfred: "well that is due to XXX other thing that is broken, thanks for 
> helping us resolve that unrelated problem!"
> customer: "i hate you"
> alfred: "get in line."

Are your customers running HEAD?  Assertions in a stable branch have been
through testing and generally aren't bogus, so dying on incorrect assertions
(meaning the assertion tripped for non-buggy code) should not be the common
case.  Thus, that shouldn't really be the basis for an argument on this.

I can also come up with arbitrary strawmen:

customer: "help!  we lost a bunch of data!"
jhb: "oh, well, I can see why: the box reported this critical error while
      your data was still there, but it went ahead and corrupted it all
      anyway even though it knew about the error because I thought you wanted
      longer uptimes"
jhb: "don't worry, I have a patch to fix the error"
customer: "don't bother, we are switching to X"

-- 
John Baldwin



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