On Thu, Mar 15, 2018 at 02:20:53PM +0000, Dexuan Cui wrote:
> When we hot-remove the device, we first receive a PCI_EJECT message and
> then receive a PCI_BUS_RELATIONS message with bus_rel->device_count == 0.
>
> The first message is offloaded to hv_eject_device_work(), and the second
> is offloaded to pci_devices_present_work(). Both the paths can be running
> list_del(&hpdev->list_entry), causing general protection fault, because
> system_wq can run them concurrently.
>
> The patch eliminates the race condition.
>
> Tested-by: Adrian Suhov <v-ads...@microsoft.com>
> Tested-by: Chris Valean <v-chv...@microsoft.com>
> Signed-off-by: Dexuan Cui <de...@microsoft.com>
> Reviewed-by: Michael Kelley <mikel...@microsoft.com>
> Acked-by: Haiyang Zhang <haiya...@microsoft.com>
> Cc: sta...@vger.kernel.org
I need to know either what commit you are fixing (ie Fixes: tag - which
is preferrable) or you tell me which kernel versions we are targeting
for the stable backport.
Thanks,
Lorenzo
> Cc: Vitaly Kuznetsov <vkuzn...@redhat.com>
> Cc: Jack Morgenstein <ja...@mellanox.com>
> Cc: Stephen Hemminger <sthem...@microsoft.com>
> Cc: K. Y. Srinivasan <k...@microsoft.com>
> ---
> drivers/pci/host/pci-hyperv.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index 2faf38eab785..5e67dff779a7 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -461,6 +461,8 @@ struct hv_pcibus_device {
> struct retarget_msi_interrupt retarget_msi_interrupt_params;
>
> spinlock_t retarget_msi_interrupt_lock;
> +
> + struct workqueue_struct *wq;
> };
>
> /*
> @@ -1770,7 +1772,7 @@ static void hv_pci_devices_present(struct
> hv_pcibus_device *hbus,
> spin_unlock_irqrestore(&hbus->device_list_lock, flags);
>
> get_hvpcibus(hbus);
> - schedule_work(&dr_wrk->wrk);
> + queue_work(hbus->wq, &dr_wrk->wrk);
> }
>
> /**
> @@ -1848,7 +1850,7 @@ static void hv_pci_eject_device(struct hv_pci_dev
> *hpdev)
> get_pcichild(hpdev, hv_pcidev_ref_pnp);
> INIT_WORK(&hpdev->wrk, hv_eject_device_work);
> get_hvpcibus(hpdev->hbus);
> - schedule_work(&hpdev->wrk);
> + queue_work(hpdev->hbus->wq, &hpdev->wrk);
> }
>
> /**
> @@ -2463,11 +2465,17 @@ static int hv_pci_probe(struct hv_device *hdev,
> spin_lock_init(&hbus->retarget_msi_interrupt_lock);
> sema_init(&hbus->enum_sem, 1);
> init_completion(&hbus->remove_event);
> + hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0,
> + hbus->sysdata.domain);
> + if (!hbus->wq) {
> + ret = -ENOMEM;
> + goto free_bus;
> + }
>
> ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0,
> hv_pci_onchannelcallback, hbus);
> if (ret)
> - goto free_bus;
> + goto destroy_wq;
>
> hv_set_drvdata(hdev, hbus);
>
> @@ -2536,6 +2544,8 @@ static int hv_pci_probe(struct hv_device *hdev,
> hv_free_config_window(hbus);
> close:
> vmbus_close(hdev->channel);
> +destroy_wq:
> + destroy_workqueue(hbus->wq);
> free_bus:
> free_page((unsigned long)hbus);
> return ret;
> @@ -2615,6 +2625,7 @@ static int hv_pci_remove(struct hv_device *hdev)
> irq_domain_free_fwnode(hbus->sysdata.fwnode);
> put_hvpcibus(hbus);
> wait_for_completion(&hbus->remove_event);
> + destroy_workqueue(hbus->wq);
> free_page((unsigned long)hbus);
> return 0;
> }
> --
> 2.7.4
>
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