Re: [PATCH 1/2] Ensure that the SCSI error handler gets woken up

From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "jthumshirn@suse.de" <jthumshirn@suse.de>
Cc: "hch@lst.de" <hch@lst.de>,
	"stuart.w.hayes@gmail.com" <stuart.w.hayes@gmail.com>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"hare@suse.com" <hare@suse.com>,
	"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
	"ptikhomirov@virtuozzo.com" <ptikhomirov@virtuozzo.com>,
	"khorenko@virtuozzo.com" <khorenko@virtuozzo.com>
Subject: Re: [PATCH 1/2] Ensure that the SCSI error handler gets woken up
Date: Fri, 1 Dec 2017 17:40:59 +0000	[thread overview]
Message-ID: <1512150058.2520.19.camel@wdc.com> (raw)
In-Reply-To: <mqd609q4z0k.fsf@linux-x5ow.site>

On Fri, 2017-12-01 at 09:45 +0100, Johannes Thumshirn wrote:
> Bart Van Assche <bart.vanassche@wdc.com> writes:
> [...]
> 
> > +	if (shost_state != shost->shost_state) {
> > +		spin_unlock_irqrestore(shost->host_lock, flags);
> > +		synchronize_rcu();
> > +		spin_lock_irqsave(shost->host_lock, flags);
> > +	}
> 
> Plese correct me if I'm wrong, but once you drop the host lock all
> assumptions about states it protects are void, aren't they? 

Hello Johannes,

That's a good question. I think it is safe to drop the host lock at that point
because waking up the error handler thread will only happen after host_failed
has been incremented.

Bart.