From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: bigeasy@linutronix.de, tglx@linutronix.de, sagi@grimberg.me,
linux-nvme@lists.infradead.org, ming.lei@redhat.com
Subject: Re: [PATCHv3 1/4] nvme/pci: Disable interrupts for threaded handler
Date: Fri, 13 Dec 2019 00:53:18 +0900 [thread overview]
Message-ID: <20191212155318.GA30611@redsun51.ssa.fujisawa.hgst.com> (raw)
In-Reply-To: <20191212090952.GB2399@lst.de>
On Thu, Dec 12, 2019 at 10:09:52AM +0100, Christoph Hellwig wrote:
> On Tue, Dec 10, 2019 at 02:56:19AM +0900, Keith Busch wrote:
> > + if (!to_pci_dev(nvmeq->dev->dev)->msix_enabled)
> > + writel(1 << nvmeq->cq_vector, nvmeq->dev->bar + NVME_REG_INTMS);
> > +
> > + disable_irq_nosync(irq);
>
> Why do we need both the device-level disable and disable_irq_nosync
> for the non-MSI-X case here?
There's a race condition that needs to be handled here. We mask the
interrupt on the device, but the device may have sent an MSI at the
same time that the APIC hasn't seen yet, and that would retrigger
the interrupt handler. We need it to see irqd_irq_disabled() is true,
otherwise the nvme primary and thread may run at the same time, which
we don't want in order to poll the cq from both.
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next prev parent reply other threads:[~2019-12-12 15:53 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 17:56 [PATCHv3 0/4] nvme pci interrupt handling improvements Keith Busch
2019-12-09 17:56 ` [PATCHv3 1/4] nvme/pci: Disable interrupts for threaded handler Keith Busch
2019-12-10 15:12 ` Daniel Wagner
2019-12-10 15:28 ` Sebastian Andrzej Siewior
2019-12-10 15:54 ` Keith Busch
2019-12-10 16:44 ` Daniel Wagner
2019-12-10 16:57 ` Keith Busch
2019-12-10 17:11 ` Daniel Wagner
2019-12-12 9:09 ` Christoph Hellwig
2019-12-12 15:53 ` Keith Busch [this message]
2019-12-09 17:56 ` [PATCHv3 2/4] nvme/pci: Complete commands from primary handler Keith Busch
2019-12-10 20:00 ` Sagi Grimberg
2019-12-10 20:25 ` Keith Busch
2019-12-10 21:14 ` Sagi Grimberg
2019-12-11 17:35 ` Keith Busch
2019-12-12 0:40 ` Sagi Grimberg
2019-12-12 1:02 ` Keith Busch
2019-12-12 22:55 ` Ming Lei
2019-12-12 23:30 ` Keith Busch
2019-12-13 0:52 ` Ming Lei
2019-12-12 9:14 ` Christoph Hellwig
2019-12-09 17:56 ` [PATCHv3 3/4] nvme/pci: Remove use_threaded_interrupts Keith Busch
2019-12-12 9:14 ` Christoph Hellwig
2019-12-12 15:45 ` Keith Busch
2019-12-18 7:29 ` Ming Lei
2019-12-18 15:50 ` Keith Busch
2019-12-19 1:10 ` Ming Lei
2019-12-09 17:56 ` [PATCHv3 4/4] nvme/pci: Poll threaded completions Keith Busch
2019-12-10 17:43 ` Daniel Wagner
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