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Message-ID: <20160527160822.GO23194@mtj.duckdns.org>
Date: Fri, 27 May 2016 12:08:22 -0400
From: Tejun Heo <tj@...nel.org>
To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: Bhaktipriya Shridhar <bhaktipriya96@...il.com>,
boris.ostrovsky@...cle.com, david.vrabel@...rix.com,
jgross@...e.com, JBeulich@...e.com, paul.gortmaker@...driver.com,
stefano.stabellini@...citrix.com, cardoe@...doe.com,
xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xen: xen-pciback: Remove create_workqueue
Hello,
On Fri, May 27, 2016 at 12:01:14PM -0400, Konrad Rzeszutek Wilk wrote:
> On Fri, May 27, 2016 at 09:24:11PM +0530, Bhaktipriya Shridhar wrote:
> > With concurrency managed workqueues, use of dedicated workqueues can be
> > replaced by using system_wq. Drop host->intr_wq by using
^
xen_pcibk_wq
> > system_wq.
> >
> > Since there is only a single work item, increase of concurrency level by
> > switching to system_wq should not break anything.
>
> _should_ not? Hehe. I presume this has not been tested?
Yeah, this is a part of sweeping conversions and it's challenging (and
often impossible for specific drivers) to setup test environments.
xen isn't as bad but can still be a pretty specialized setup. The
conversions aren't high risk and shouldn't be too difficult to root
cause when something goes south. We'd greatly appreciate any helps
with reviewing and testing.
> > cancel_work_sync() has been used in xen_pcibk_disconnect() to ensure that
> > work item is not pending or executing by the time exit path runs.
> >
> > Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@...il.com>
> > @@ -76,8 +75,7 @@ static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
> > /* If the driver domain started an op, make sure we complete it
> > * before releasing the shared memory */
> >
> > - /* Note, the workqueue does not use spinlocks at all.*/
> > - flush_workqueue(xen_pcibk_wq);
> > + cancel_work_sync(&pdev->op_work);
Should it be flush_work() instead? Is it okay for a pdev->op_work to
be queued and canceled without actually getting executed?
Thanks.
--
tejun
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