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Subject: Re: [PATCH 0/8] Drop host_lock around LLD SHT->queuecommand()
	caller
From: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: linux-scsi <linux-scsi@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Vasu Dev <vasu.dev@linux.intel.com>, Andi Kleen <ak@linux.intel.com>,
        Matthew Wilcox <willy@linux.intel.com>,
        James Bottomley <James.Bottomley@suse.de>,
        Mike Christie <michaelc@cs.wisc.edu>,
        James Smart <james.smart@emulex.com>,
        Andrew Vasquez <andrew.vasquez@qlogic.com>,
        FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
        Hannes Reinecke <hare@suse.de>, Joe Eykholt <jeykholt@cisco.com>,
        Christoph Hellwig <hch@lst.de>
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Date: Thu, 16 Sep 2010 18:31:10 -0700
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On Thu, 2010-09-16 at 18:29 -0700, Tim Chen wrote:
> On Thu, 2010-09-16 at 15:35 -0700, Nicholas A. Bellinger wrote:
> > From: Nicholas Bellinger <nab@linux-iscsi.org>
> > 
> > Greetings all,
> > 
> > This series contains the first round of a whole-sale conversion for droping
> > struct Scsi_Host->host_lock around struct Scsi_Host->queuecommand() within
> > scsi_dispatch_cmd().  So with this first patch the only part of scsi_dispatch_cmd()
> > that is protected by host_lock is scsi_cmd_get_serial)_.
> > 
> 
> Maybe we can change the host->cmd_serial_number to atomic and totally
> avoid the need to take host_lock.

Hmmmm good point, then we would also need an atomic_t for signaling
(shost_state == SHOST_DEL) in scsi_dispatch_cmd() to be able to
completly drop host_lock usage within scsi_dispatch_cmd().

I can take a look at doing this specific part, if you would be willing
to have a look at the host->cmd_serial_number conversion piece.  ;)

Thanks Tim!

--nab