From: longli@linuxonhyperv.com
To: "K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Rob Herring <robh@kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Long Li <longli@microsoft.com>
Subject: [Patch v2 1/2] PCI: hv: Fix a race condition when removing the device
Date: Wed, 21 Apr 2021 22:45:45 -0700 [thread overview]
Message-ID: <1619070346-21557-1-git-send-email-longli@linuxonhyperv.com> (raw)
From: Long Li <longli@microsoft.com>
On removing the device, any work item (hv_pci_devices_present() or
hv_pci_eject_device()) scheduled on workqueue hbus->wq may still be running
and race with hv_pci_remove().
This can happen because the host may send PCI_EJECT or PCI_BUS_RELATIONS(2)
and decide to rescind the channel immediately after that.
Fix this by flushing/stopping the workqueue of hbus before doing hbus remove.
Signed-off-by: Long Li <longli@microsoft.com>
---
Change in v2: Remove unused bus state hv_pcibus_removed
drivers/pci/controller/pci-hyperv.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 27a17a1e4a7c..fc948a2ed703 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -444,7 +444,6 @@ enum hv_pcibus_state {
hv_pcibus_probed,
hv_pcibus_installed,
hv_pcibus_removing,
- hv_pcibus_removed,
hv_pcibus_maximum
};
@@ -3305,13 +3304,22 @@ static int hv_pci_remove(struct hv_device *hdev)
hbus = hv_get_drvdata(hdev);
if (hbus->state == hv_pcibus_installed) {
+ tasklet_disable(&hdev->channel->callback_event);
+ hbus->state = hv_pcibus_removing;
+ tasklet_enable(&hdev->channel->callback_event);
+ destroy_workqueue(hbus->wq);
+ /*
+ * At this point, no work is running or can be scheduled
+ * on hbus-wq. We can't race with hv_pci_devices_present()
+ * or hv_pci_eject_device(), it's safe to proceed.
+ */
+
/* Remove the bus from PCI's point of view. */
pci_lock_rescan_remove();
pci_stop_root_bus(hbus->pci_bus);
hv_pci_remove_slots(hbus);
pci_remove_root_bus(hbus->pci_bus);
pci_unlock_rescan_remove();
- hbus->state = hv_pcibus_removed;
}
ret = hv_pci_bus_exit(hdev, false);
@@ -3326,7 +3334,6 @@ 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);
hv_put_dom_num(hbus->sysdata.domain);
--
2.27.0
next reply other threads:[~2021-04-22 5:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-22 5:45 longli [this message]
2021-04-22 5:45 ` [Patch v2 2/2] PCI: hv: Remove unused refcount and supporting functions for handling bus device removal longli
2021-04-23 7:18 ` Dexuan Cui
2021-04-23 18:40 ` Long Li
2021-04-25 2:57 ` Dexuan Cui
2021-04-23 7:09 ` [Patch v2 1/2] PCI: hv: Fix a race condition when removing the device Dexuan Cui
2021-04-23 18:32 ` Long Li
2021-04-23 18:41 ` Dexuan Cui
2021-04-23 18:49 ` Long Li
2021-04-25 2:24 ` Dexuan Cui
2021-04-25 4:53 ` Long Li
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