From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mike Christie <michaelc@cs.wisc.edu>
Subject: Re: [PATCH 01/11] libiscsi: Convert to host_lock less w/ interrupts
 disabled internally
Date: Wed, 17 Nov 2010 19:06:26 -0600
Message-ID: <4CE47C12.80804@cs.wisc.edu>
References: <1290032304-4859-1-git-send-email-nab@linux-iscsi.org>
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To: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: linux-scsi <linux-scsi@vger.kernel.org>, Jeff Garzik <jeff@garzik.org>, James Bottomley <James.Bottomley@suse.de>, Christoph Hellwig <hch@lst.de>, Ravi Anand <ravi.anand@qlogic.com>, Andrew Vasquez <andrew.vasquez@qlogic.com>, Joe Eykholt <jeykholt@cisco.com>, James Smart <james.smart@emulex.com>, Vasu Dev <vasu.dev@linux.intel.com>, Tim Chen <tim.c.chen@linux.intel.com>, Andi Kleen <ak@linux.intel.com>, Tejun Heo <tj@kernel.org>, Mike Anderson <andmike@linux.vnet.ibm.com>, MPTFusionLinux <DL-MPTFusionLinux@lsi.com>

On 11/17/2010 04:18 PM, Nicholas A. Bellinger wrote:
>   prepd_fault:
>   	sc->scsi_done = NULL;

> -	done(sc);
> -	spin_lock(host->host_lock);
> +	sc->scsi_done(sc);
>   	return 0;

This will NULL pointer. See a couple lines above where we NULL it. 
iscsi_free_task checks if the scsi_done pointer is set and if it is it 
will call scsi_done.

It is a hack to prevent the normal completion path from calling 
scsi_done. For the case where we return SCSI_MLQUEUE_TARGET_BUSY (the 
prepd_reject case) we need something to prevent scsi_done from getting 
called.

For the return 0/prepd_fault case we can just call sc->scsi_done, but we 
have to move some code around.

I do not like how the code does the NULLing and testing. Let me work on 
this and send a tested patch.