From: Long Li longli@microsoft.com
[ Upstream commit 94d22763207ac6633612b8d8e0ca4fba0f7aa139 ]
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/destroying the workqueue of hbus before doing hbus remove.
Link: https://lore.kernel.org/r/1620806800-30983-1-git-send-email-longli@linuxonhy... Signed-off-by: Long Li longli@microsoft.com Signed-off-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Reviewed-by: Michael Kelley mikelley@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/controller/pci-hyperv.c | 30 ++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 7479edf3676c..fd30f70c7560 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 };
@@ -3247,8 +3246,9 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs) struct pci_packet teardown_packet; u8 buffer[sizeof(struct pci_message)]; } pkt; - struct hv_dr_state *dr; struct hv_pci_compl comp_pkt; + struct hv_pci_dev *hpdev, *tmp; + unsigned long flags; int ret;
/* @@ -3260,9 +3260,16 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
if (!keep_devs) { /* Delete any children which might still exist. */ - dr = kzalloc(sizeof(*dr), GFP_KERNEL); - if (dr && hv_pci_start_relations_work(hbus, dr)) - kfree(dr); + spin_lock_irqsave(&hbus->device_list_lock, flags); + list_for_each_entry_safe(hpdev, tmp, &hbus->children, list_entry) { + list_del(&hpdev->list_entry); + if (hpdev->pci_slot) + pci_destroy_slot(hpdev->pci_slot); + /* For the two refs got in new_pcichild_device() */ + put_pcichild(hpdev); + put_pcichild(hpdev); + } + spin_unlock_irqrestore(&hbus->device_list_lock, flags); }
ret = hv_send_resources_released(hdev); @@ -3305,13 +3312,23 @@ 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); + hbus->wq = NULL; + /* + * 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 +3343,6 @@ 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);