hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

PCI: hv: Fix a race condition when removing the device 

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@linuxonhyperv.com
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
This commit is contained in:
Long Li 2021-05-12 01:06:40 -07:00 committed by Lorenzo Pieralisi
parent 6efb943b86
commit 94d2276320
1 changed files with 23 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
drivers/pci/controller/pci-hyperv.c
View File

@ -444,7 +444,6 @@ enum hv_pcibus_state {
hv_pcibus_probed,
hv_pcibus_installed,
hv_pcibus_removing,
hv_pcibus_removed,
hv_pcibus_maximum
};
@ -3243,8 +3242,9 @@ 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;
/*
@ -3256,9 +3256,16 @@ 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);
@ -3301,13 +3308,23 @@ 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);
@ -3322,7 +3339,6 @@ 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);