linux-kernel - RE: [PATCH 2/2 v3] pci-hyperv: lock pci bus on device eject

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Date:   Mon, 9 Jan 2017 22:52:07 +0000
From:   Long Li <longli@...rosoft.com>
To:     KY Srinivasan <kys@...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>
Subject: RE: [PATCH 2/2 v3] pci-hyperv: lock pci bus on device eject

Hi Bjorn,

The patch is still pending (along with 1/2 v3). Please let me know if you want me to resend the two patches.

Thanks

Long

> -----Original Message-----
> From: KY Srinivasan
> Sent: Tuesday, October 4, 2016 1:49 PM
> To: Long Li <longli@...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
> Subject: RE: [PATCH 2/2 v3] pci-hyperv: lock pci bus on device eject
> 
> 
> 
> > -----Original Message-----
> > From: Long Li
> > Sent: Monday, October 3, 2016 11:43 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: [PATCH 2/2 v3] pci-hyperv: lock pci bus on device eject
> >
> > 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>
> >
> > A PCI_EJECT message can arrive at the same time we are calling
> > pci_scan_child_bus in the workqueue for the previous
> PCI_BUS_RELATIONS
> > message or in create_root_hv_pci_bus(), in this case we could
> > potentailly modify the bus from multiple places. Properly lock the bus
> access.
> >
> > Thanks Dexuan Cui <decui@...rosoft.com> for pointing out the race
> > condition in create_root_hv_pci_bus().
> >
> > Signed-off-by: Long Li <longli@...rosoft.com>
> > Tested-by: Cathy Avery <cavery@...hat.com>
> > Reported-by: Xiaofeng Wang <xiaofwan@...hat.com>
> 
> Acked-by: KY Srinivasan <kys@...rosoft.com>
> 
> > ---
> >  drivers/pci/host/pci-hyperv.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/pci/host/pci-hyperv.c
> > b/drivers/pci/host/pci-hyperv.c index 4a37598..33c75c9 100644
> > --- a/drivers/pci/host/pci-hyperv.c
> > +++ b/drivers/pci/host/pci-hyperv.c
> > @@ -1198,9 +1198,11 @@ static int create_root_hv_pci_bus(struct
> > hv_pcibus_device *hbus)
> >         hbus->pci_bus->msi = &hbus->msi_chip;
> >         hbus->pci_bus->msi->dev = &hbus->hdev->device;
> >
> > +       pci_lock_rescan_remove();
> >         pci_scan_child_bus(hbus->pci_bus);
> >         pci_bus_assign_resources(hbus->pci_bus);
> >         pci_bus_add_devices(hbus->pci_bus);
> > +       pci_unlock_rescan_remove();
> >         hbus->state = hv_pcibus_installed;
> >         return 0;
> >  }
> > @@ -1590,8 +1592,10 @@ static void hv_eject_device_work(struct
> > work_struct *work)
> >         pdev =
> > pci_get_domain_bus_and_slot(hpdev->hbus->sysdata.domain,
> > 0,
> >                                            wslot);
> >         if (pdev) {
> > +               pci_lock_rescan_remove();
> >                 pci_stop_and_remove_bus_device(pdev);
> >                 pci_dev_put(pdev);
> > +               pci_unlock_rescan_remove();
> >         }
> >
> >         memset(&ctxt, 0, sizeof(ctxt));
> > --
> > 1.8.5.6