linux-kernel - RE: [PATCH 3/3] PCI: hv: Add pci_destroy_slot() in pci_devices_present

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Date:   Wed, 20 Mar 2019 21:44:06 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     Dexuan Cui <decui@...rosoft.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
CC:     "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "driverdev-devel@...uxdriverproject.org" 
        <driverdev-devel@...uxdriverproject.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        vkuznets <vkuznets@...hat.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        "jackm@...lanox.com" <jackm@...lanox.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH 3/3] PCI: hv: Add pci_destroy_slot() in
 pci_devices_present_work(), if necessary

From: Dexuan Cui <decui@...rosoft.com>  Sent: Monday, March 4, 2019 1:35 PM
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index b489412e3502..82acd6155adf 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1776,6 +1776,10 @@ static void pci_devices_present_work(struct work_struct *work)
>  		hpdev = list_first_entry(&removed, struct hv_pci_dev,
>  					 list_entry);
>  		list_del(&hpdev->list_entry);
> +
> +		if (hpdev->pci_slot)
> +			pci_destroy_slot(hpdev->pci_slot);

The code is inconsistent in whether hpdev->pci_slot is set to NULL after calling
pci_destory_slot().  Patch 2 in this series does set it to NULL, but this code does not.
And the code in hv_eject_device_work() does not set it to NULL.

It looks like all the places that test the value of hpdev->pci_slot or call
pci_destroy_slot() are serialized, so it looks like it really doesn't matter.  But when
the code is inconsistent about setting to NULL, it always makes me wonder if there
is a reason.

Michael


> +
>  		put_pcichild(hpdev);
>  	}
> 
> --
> 2.19.1