linux-kernel - [PATCH 4.9 111/223] PCI: hv: Delete the device earlier from hbus->children for hot-remove

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Message-Id: <20190802092246.437519832@linuxfoundation.org>
Date:   Fri,  2 Aug 2019 11:35:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dexuan Cui <decui@...rosoft.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jake Oshins <jakeo@...rosoft.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: [PATCH 4.9 111/223] PCI: hv: Delete the device earlier from hbus->children for hot-remove

From: Dexuan Cui <decui@...rosoft.com>

commit e74d2ebdda33b3bdd1826b5b92e9aa45bdf92bb3 upstream.

After we send a PCI_EJECTION_COMPLETE message to the host, the host will
immediately send us a PCI_BUS_RELATIONS message with
relations->device_count == 0, so pci_devices_present_work(), running on
another thread, can find the being-ejected device, mark the
hpdev->reported_missing to true, and run list_move_tail()/list_del() for
the device -- this races hv_eject_device_work() -> list_del().

Move the list_del() in hv_eject_device_work() to an earlier place, i.e.,
before we send PCI_EJECTION_COMPLETE, so later the
pci_devices_present_work() can't see the device.

Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Reviewed-by: Jake Oshins <jakeo@...rosoft.com>
Acked-by: K. Y. Srinivasan <kys@...rosoft.com>
CC: Haiyang Zhang <haiyangz@...rosoft.com>
CC: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/host/pci-hyperv.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1607,6 +1607,10 @@ static void hv_eject_device_work(struct
 		pci_unlock_rescan_remove();
 	}

+	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
+	list_del(&hpdev->list_entry);
+	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
+
 	memset(&ctxt, 0, sizeof(ctxt));
 	ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
 	ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
@@ -1615,10 +1619,6 @@ static void hv_eject_device_work(struct
 			 sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,
 			 VM_PKT_DATA_INBAND, 0);

-	spin_lock_irqsave(&hpdev->hbus->device_list_lock, flags);
-	list_del(&hpdev->list_entry);
-	spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
-
 	put_pcichild(hpdev, hv_pcidev_ref_childlist);
 	put_pcichild(hpdev, hv_pcidev_ref_initial);
 	put_pcichild(hpdev, hv_pcidev_ref_pnp);