From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "ptikhomirov@virtuozzo.com" <ptikhomirov@virtuozzo.com>
Cc: "jthumshirn@suse.de" <jthumshirn@suse.de>,
"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>,
"khorenko@virtuozzo.com" <khorenko@virtuozzo.com>
Subject: Re: [PATCH v3 1/2] Ensure that the SCSI error handler gets woken up
Date: Tue, 5 Dec 2017 16:19:50 +0000 [thread overview]
Message-ID: <1512490788.2660.16.camel@wdc.com> (raw)
In-Reply-To: <8514bfc3-4d11-be94-eef4-82f48d436656@virtuozzo.com>
On Tue, 2017-12-05 at 13:18 +0300, Pavel Tikhomirov wrote:
> On 12/04/2017 09:06 PM, Bart Van Assche wrote:
> > +static void scsi_eh_inc_host_failed(struct rcu_head *head)
> > +{
> > + struct Scsi_Host *shost = container_of(head, typeof(*shost), rcu);
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(shost->host_lock, flags);
> > + shost->host_failed++;
>
> May be we need to increment host_failed before call_rcu(), so that all
> rcu protected readers already see a change at these point?
Sorry but I don't think that would work. If host_failed would be changed first
then it can happen that scsi_dec_host_busy() encounters that the host state is
"running" and hence that it skips the host_failed check. That can result in a
missed error handler wakeup, which is what we want to avoid.
Bart.
next prev parent reply other threads:[~2017-12-05 16:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-04 18:06 [PATCH v3 0/2] Ensure that the SCSI error handler gets woken up Bart Van Assche
2017-12-04 18:06 ` [PATCH v3 1/2] " Bart Van Assche
2017-12-05 10:18 ` Pavel Tikhomirov
2017-12-05 16:19 ` Bart Van Assche [this message]
[not found] ` <sr4inbsihn7krboba8euqqp1.1512508675214@email.android.com>
2017-12-05 21:46 ` Bart Van Assche
2017-12-05 22:49 ` Pavel Tikhomirov
2017-12-05 22:59 ` Bart Van Assche
2017-12-06 7:20 ` Pavel Tikhomirov
2017-12-07 5:12 ` Stuart Hayes
2017-12-04 18:06 ` [PATCH v3 2/2] Convert a source code comment into a runtime check Bart Van Assche
2017-12-07 1:55 ` [PATCH v3 0/2] Ensure that the SCSI error handler gets woken up Martin K. Petersen
2017-12-07 12:02 ` John Garry
2017-12-07 16:50 ` Bart Van Assche
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