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Date:      Thu, 17 Nov 2011 10:34:26 +0200
From:      Andriy Gapon <avg@FreeBSD.org>
To:        Kostik Belousov <kostikbel@gmail.com>
Cc:        Alexander Motin <mav@FreeBSD.org>, freebsd-current@FreeBSD.org
Subject:   Re: Stop scheduler on panic
Message-ID:  <4EC4C712.8040701@FreeBSD.org>
In-Reply-To: <20111117081533.GP50300@deviant.kiev.zoral.com.ua>
References:  <20111113083215.GV50300@deviant.kiev.zoral.com.ua> <20111116202714.5ee4bd53@fabiankeil.de> <4EC43764.1020202@FreeBSD.org> <4EC4423A.3020904@FreeBSD.org> <20111117081533.GP50300@deviant.kiev.zoral.com.ua>

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on 17/11/2011 10:15 Kostik Belousov said the following:
> On Thu, Nov 17, 2011 at 01:07:38AM +0200, Alexander Motin wrote:
>> On 17.11.2011 00:21, Andriy Gapon wrote:
>>> Going further up the stack one can come up with the following proposals:
>>> - check SCHEDULER_STOPPED() swi_sched() and return early
>>> - do not call swi_sched() from xpt_done() if we somehow know that we are 
>>> in a
>>> polling mode
>>
>> There is no flag in CAM now to indicate polling mode, but if needed, it 
>> should not be difficult to add one and not call swi_sched().
> 
> I have the following change for eons on my test boxes. Without it,
> I simply cannot get _any_ dump.
> 
> diff --git a/sys/cam/cam_xpt.c b/sys/cam/cam_xpt.c
> index 10b89c7..a38e42f 100644
> --- a/sys/cam/cam_xpt.c
> +++ b/sys/cam/cam_xpt.c
> @@ -4230,7 +4230,7 @@ xpt_done(union ccb *done_ccb)
>  			TAILQ_INSERT_TAIL(&cam_simq, sim, links);
>  			mtx_unlock(&cam_simq_lock);
>  			sim->flags |= CAM_SIM_ON_DONEQ;
> -			if (first)
> +			if (first && panicstr == NULL)
>  				swi_sched(cambio_ih, 0);
>  		}
>  	}

I think that this (or similar) change should go into the patch and the tree.

-- 
Andriy Gapon



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