linux-kernel - RE: [Resend PATCH 1/2 v3] pci-hyperv: properly handle pci bus remove

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Message-ID: <DM5PR03MB2490322EC48F7332D9ED3CB7A0760@DM5PR03MB2490.namprd03.prod.outlook.com>
Date:   Fri, 27 Jan 2017 18:42:24 +0000
From:   KY Srinivasan <kys@...rosoft.com>
To:     Long Li <longli@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Long Li <longli@...rosoft.com>
Subject: RE: [Resend PATCH 1/2 v3] pci-hyperv: properly handle pci bus remove



> -----Original Message-----
> From: Long Li [mailto:longli@...hange.microsoft.com]
> Sent: Monday, January 23, 2017 9:45 PM
> To: KY Srinivasan <kys@...rosoft.com>; Haiyang Zhang
> <haiyangz@...rosoft.com>; Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: devel@...uxdriverproject.org; linux-pci@...r.kernel.org; linux-
> kernel@...r.kernel.org; Long Li <longli@...rosoft.com>
> Subject: [Resend PATCH 1/2 v3] pci-hyperv: properly handle pci bus remove
> 
> [This sender failed our fraud detection checks and may not be who they
> appear to be. Learn about spoofing at http://aka.ms/LearnAboutSpoofing]
> 
> From: Long Li <longli@...rosoft.com>
> 
> hv_pci_devices_present is called in hv_pci_remove when we remove a PCI
> device from host (e.g. by disabling SRIOV on a device). In hv_pci_remove,
> the bus is already removed before the call, so we don't need to rescan the
> bus in the workqueue scheduled from hv_pci_devices_present. By
> introducing status hv_pcibus_removed, we can avoid this situation.
> 
> Signed-off-by: Long Li <longli@...rosoft.com>
> Reported-by: Xiaofeng Wang <xiaofwan@...hat.com>
Acked-by: K. Y. Srinivasan <kys@...rosoft.com>
> ---
>  drivers/pci/host/pci-hyperv.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index a8deeca..4a37598 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -348,6 +348,7 @@ enum hv_pcibus_state {
>         hv_pcibus_init = 0,
>         hv_pcibus_probed,
>         hv_pcibus_installed,
> +       hv_pcibus_removed,
>         hv_pcibus_maximum
>  };
> 
> @@ -1481,13 +1482,24 @@ static void pci_devices_present_work(struct
> work_struct *work)
>                 put_pcichild(hpdev, hv_pcidev_ref_initial);
>         }
> 
> -       /* Tell the core to rescan bus because there may have been changes. */
> -       if (hbus->state == hv_pcibus_installed) {
> +       switch (hbus->state) {
> +       case hv_pcibus_installed:
> +               /*
> +                * Tell the core to rescan bus
> +                * because there may have been changes.
> +                */
>                 pci_lock_rescan_remove();
>                 pci_scan_child_bus(hbus->pci_bus);
>                 pci_unlock_rescan_remove();
> -       } else {
> +               break;
> +
> +       case hv_pcibus_init:
> +       case hv_pcibus_probed:
>                 survey_child_resources(hbus);
> +               break;
> +
> +       default:
> +               break;
>         }
> 
>         up(&hbus->enum_sem);
> @@ -2163,6 +2175,7 @@ static int hv_pci_probe(struct hv_device *hdev,
>         hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);
>         if (!hbus)
>                 return -ENOMEM;
> +       hbus->state = hv_pcibus_init;
> 
>         /*
>          * The PCI bus "domain" is what is called "segment" in ACPI and
> @@ -2305,6 +2318,7 @@ static int hv_pci_remove(struct hv_device *hdev)
>                 pci_stop_root_bus(hbus->pci_bus);
>                 pci_remove_root_bus(hbus->pci_bus);
>                 pci_unlock_rescan_remove();
> +               hbus->state = hv_pcibus_removed;
>         }
> 
>         ret = hv_send_resources_released(hdev);
> --
> 1.8.5.6