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From: Keith Busch <kbusch@kernel.org>
To: Lukas Wunner <lukas@wunner.de>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	Xiongfeng Wang <wangxiongfeng2@huawei.com>
Subject: Re: [PATCH] PCI: pciehp: Avoid returning prematurely from sysfs requests
Date: Fri, 9 Aug 2019 13:32:16 -0600	[thread overview]
Message-ID: <20190809193216.GD28515@localhost.localdomain> (raw)
In-Reply-To: <4174210466e27eb7e2243dd1d801d5f75baaffd8.1565345211.git.lukas@wunner.de>

On Fri, Aug 09, 2019 at 12:28:43PM +0200, Lukas Wunner wrote:
> A sysfs request to enable or disable a PCIe hotplug slot should not
> return before it has been carried out.  That is sought to be achieved
> by waiting until the controller's "pending_events" have been cleared.
> 
> However the IRQ thread pciehp_ist() clears the "pending_events" before
> it acts on them.  If pciehp_sysfs_enable_slot() / _disable_slot() happen
> to check the "pending_events" after they have been cleared but while
> pciehp_ist() is still running, the functions may return prematurely
> with an incorrect return value.
> 
> Fix by introducing an "ist_running" flag which must be false before a
> sysfs request is allowed to return.

Can you instead just call synchronize_irq(ctrl->pcie->irq) after the
pending events is cleared?

  parent reply	other threads:[~2019-08-09 19:34 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 10:28 [PATCH] PCI: pciehp: Avoid returning prematurely from sysfs requests Lukas Wunner
2019-08-09 17:28 ` sathyanarayanan kuppuswamy
2019-08-09 18:28   ` Lukas Wunner
2019-08-09 19:32 ` Keith Busch [this message]
2019-08-09 20:28   ` Lukas Wunner
2019-08-10 10:12     ` Lukas Wunner
2019-10-04 20:41 ` Bjorn Helgaas

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