[v2,3/6] PCI: hv: serialize the present/eject work items

Commit Message

Dexuan Cui March 5, 2018, 7:22 p.m. UTC

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.

Signed-off-by: Dexuan Cui <[e-mail]>
Tested-by: Adrian Suhov <[e-mail]>
Tested-by: Chris Valean <[e-mail]>
Cc: Vitaly Kuznetsov <[e-mail]>
Cc: Jack Morgenstein <[e-mail]>
Cc: [e-mail]
Cc: Stephen Hemminger <[e-mail]>
Cc: K. Y. Srinivasan <[e-mail]>
---
 drivers/pci/host/pci-hyperv.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 04edb24c92ee..aaee41faf55f 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);
 }
 
 /**
@@ -1845,7 +1847,7 @@  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);
 }
 
 /**
@@ -2460,11 +2462,17 @@  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);
 
@@ -2533,6 +2541,8 @@  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;
@@ -2612,6 +2622,7 @@  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;
 }