From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 2/4] scsi: Fix device removal NULL pointer dereference
Date: Mon, 25 Jun 2012 14:21:07 -0700
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To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Bart Van Assche <bvanassche@acm.org>, linux-scsi <linux-scsi@vger.kernel.org>, Mike Christie <michaelc@cs.wisc.edu>, Jens Axboe <axboe@kernel.dk>, Jun'ichi Nomura <j-nomura@ce.jp.nec.com>, Stefan Richter <stefanr@s5r6.in-berlin.de>

Hey, James.

On Mon, Jun 25, 2012 at 10:14:49PM +0100, James Bottomley wrote:
> > @@ -1490,11 +1489,7 @@ static void scsi_request_fn(struct request_queue *q)
> >  	struct scsi_cmnd *cmd;
> >  	struct request *req;
> >  
> > -	if (!sdev) {
> > -		while ((req = blk_peek_request(q)) != NULL)
> > -			scsi_kill_request(req, q);
> > -		return;
> > -	}
> 
> That means that this hunk of code has to stay, but needs to be gated on
> blk_queue_dead(q); there's still a race where this can occur.

Wouldn't the scsi_device_online() check down below be enough?  Block
layer drain is gonna loop until all requests are done, so the looping
is handled from block layer.

Thanks.

-- 
tejun