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Date:   Mon, 16 Nov 2020 18:22:20 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     "Martin K . Petersen" <martin.petersen@oracle.com>,
        "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
        Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
        linux-scsi@vger.kernel.org, linux-block@vger.kernel.org,
        James Bottomley <James.Bottomley@HansenPartnership.com>,
        Woody Suwalski <terraluna977@gmail.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Can Guo <cang@codeaurora.org>,
        Stanley Chu <stanley.chu@mediatek.com>,
        Ming Lei <ming.lei@redhat.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Stan Johnson <userm57@yahoo.com>
Subject: Re: [PATCH v2 7/9] scsi_transport_spi: Freeze request queues
 instead of quiescing
Message-ID: <20201116172220.GG22007@lst.de>
References: <20201116030459.13963-1-bvanassche@acm.org> <20201116030459.13963-8-bvanassche@acm.org>
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On Sun, Nov 15, 2020 at 07:04:57PM -0800, Bart Van Assche wrote:
> Instead of quiescing the request queues involved in domain validation,
> freeze these. As a result, the struct request_queue pm_only member is no
> longer set during domain validation. That will allow to modify
> scsi_execute() such that it stops setting the BLK_MQ_REQ_PREEMPT flag.
> Three additional changes in this patch are that scsi_mq_alloc_queue() is
> exported, that scsi_device_quiesce() is no longer exported and that
> scsi_target_{quiesce,resume}() have been changed into
> scsi_target_{freeze,unfreeze}().

Can you explain why you need the new request_queue?  spi_dv_device seems
to generally be called from ->slave_configure where no other I/O
should ever be pending.

> +++ b/drivers/scsi/scsi_lib.c
> @@ -1893,6 +1893,7 @@ struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
>  	blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, q);
>  	return q;
>  }
> +EXPORT_SYMBOL_GPL(scsi_mq_alloc_queue);

I'd much rather open scsi_mq_alloc_queue in a new caller, especially
given that __scsi_init_queue already is exported.