> From: gregkh@xxxxxxxxxxxxxxxxxxx <gregkh@xxxxxxxxxxxxxxxxxxx>
> Sent: Wednesday, May 15, 2019 1:36 AM
> To: Dexuan Cui <decui@xxxxxxxxxxxxx>; lorenzo.pieralisi@xxxxxxx; Michael
> Kelley <mikelley@xxxxxxxxxxxxx>; stephen@xxxxxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Subject: FAILED: patch "[PATCH] PCI: hv: Add pci_destroy_slot() in" failed to
> apply to 4.14-stable tree
>
>
> The patch below does not apply to the 4.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 340d455699400f2c2c0f9b3f703ade3085cdb501 Mon Sep 17 00:00:00
> 2001
> From: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Date: Mon, 4 Mar 2019 21:34:49 +0000
> Subject: [PATCH] PCI: hv: Add pci_destroy_slot() in
> pci_devices_present_work(), if necessary
>
> When we hot-remove a device, usually the host sends us a PCI_EJECT message,
> and a PCI_BUS_RELATIONS message with bus_rel->device_count == 0.
>
> When we execute the quick hot-add/hot-remove test, the host may not send
> us the PCI_EJECT message if the guest has not fully finished the
> initialization by sending the PCI_RESOURCES_ASSIGNED* message to the
> host, so it's potentially unsafe to only depend on the
> pci_destroy_slot() in hv_eject_device_work() because the code path
>
> create_root_hv_pci_bus()
> -> hv_pci_assign_slots()
>
> is not called in this case. Note: in this case, the host still sends the
> guest a PCI_BUS_RELATIONS message with bus_rel->device_count == 0.
>
> In the quick hot-add/hot-remove test, we can have such a race before
> the code path
>
> pci_devices_present_work()
> -> new_pcichild_device()
>
> adds the new device into the hbus->children list, we may have already
> received the PCI_EJECT message, and since the tasklet handler
>
> hv_pci_onchannelcallback()
>
> may fail to find the "hpdev" by calling
>
> get_pcichild_wslot(hbus, dev_message->wslot.slot)
>
> hv_pci_eject_device() is not called; Later, by continuing execution
>
> create_root_hv_pci_bus()
> -> hv_pci_assign_slots()
>
> creates the slot and the PCI_BUS_RELATIONS message with
> bus_rel->device_count == 0 removes the device from hbus->children, and
> we end up being unable to remove the slot in
>
> hv_pci_remove()
> -> hv_pci_remove_slots()
>
> Remove the slot in pci_devices_present_work() when the device
> is removed to address this race.
>
> pci_devices_present_work() and hv_eject_device_work() run in the
> singled-threaded hbus->wq, so there is not a double-remove issue for the
> slot.
>
> We cannot offload hv_pci_eject_device() from hv_pci_onchannelcallback()
> to the workqueue, because we need the hv_pci_onchannelcallback()
> synchronously call hv_pci_eject_device() to poll the channel
> ringbuffer to work around the "hangs in hv_compose_msi_msg()" issue
> fixed in commit de0aa7b2f97d ("PCI: hv: Fix 2 hang issues in
> hv_compose_msi_msg()")
>
> Fixes: a15f2c08c708 ("PCI: hv: support reporting serial number as slot
> information")
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> [lorenzo.pieralisi@xxxxxxx: rewritten commit log]
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Reviewed-by: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
>
> 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);
> +
> put_pcichild(hpdev);
> }
>
Hi,
I backported the patch for linux-4.14.y.
Please use the attached patch, which is [PATCH 3/3]
Thanks,
-- Dexuan
Attachment:
For_v4.14.119-0003-PCI-hv-Add-pci_destroy_slot-in-pci_devices_present_w.patch
Description: For_v4.14.119-0003-PCI-hv-Add-pci_destroy_slot-in-pci_devices_present_w.patch
