From: Bjorn Helgaas <helgaas@kernel.org>
To: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Austin Bolen <austin_bolen@dell.com>,
keith.busch@intel.com, Alexandru Gagniuc <mr.nuke.me@gmail.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
"Gustavo A . R . Silva" <gustavo@embeddedor.com>,
Sinan Kaya <okaya@kernel.org>,
Oza Pawandeep <poza@codeaurora.org>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
lukas@wunner.de
Subject: Re: [PATCH] PCI: pciehp: Make sure pciehp_isr clears interrupt events
Date: Tue, 26 Nov 2019 17:37:35 -0600 [thread overview]
Message-ID: <20191126233735.GA215993@google.com> (raw)
In-Reply-To: <a7ac93e3-9a1f-2cd5-bf0b-30b562bd707d@gmail.com>
On Mon, Nov 25, 2019 at 03:03:23PM -0600, Stuart Hayes wrote:
>
> On 11/12/19 3:59 PM, Stuart Hayes wrote:
> > The pciehp interrupt handler pciehp_isr() will read the slot status
> > register and then write back to it to clear just the bits that caused the
> > interrupt. If a different interrupt event bit gets set between the read and
> > the write, pciehp_isr() will exit without having cleared all of the
> > interrupt event bits, so we will never get another hotplug interrupt from
> > that device.
> >
> > That is expected behavior according to the PCI Express spec (v.5.0, section
> > 6.7.3.4, "Software Notification of Hot-Plug Events").
> >
> > Because the "presence detect changed" and "data link layer state changed"
> > event bits are both getting set at nearly the same time when a device is
> > added or removed, this is more likely to happen than it might seem. The
> > issue can be reproduced rather easily by connecting and disconnecting an
> > NVMe device on at least one system model.
> >
> > This patch fixes the issue by modifying pciehp_isr() to loop back and
> > re-read the slot status register immediately after writing to it, until
> > it sees that all of the event status bits have been cleared.
> >
> > Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
>
> Bjorn,
>
> Do you have any comments or issues with this patch set? Anything I can do?
Were you planning to address Lukas' comments?
https://lore.kernel.org/r/20191114025022.wz3gchr7w67fjtzn@wunner.de
next prev parent reply other threads:[~2019-11-26 23:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 21:59 [PATCH] PCI: pciehp: Make sure pciehp_isr clears interrupt events Stuart Hayes
2019-11-13 4:59 ` Lukas Wunner
2019-11-13 21:58 ` Stuart Hayes
2019-11-14 2:50 ` Lukas Wunner
2019-11-13 12:13 ` kbuild test robot
2019-11-25 21:03 ` Stuart Hayes
2019-11-26 23:37 ` Bjorn Helgaas [this message]
2019-11-27 0:06 ` Stuart Hayes
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