PCI: hv: Fix sleep while in non-sleep context when removing child devices from the bus

In hv_pci_bus_exit, the code is holding a spinlock while calling
pci_destroy_slot(), which takes a mutex.

This is not safe for spinlock. Fix this by moving the children to be
deleted to a list on the stack, and removing them after spinlock is
released.

Fixes: 94d22763207a ("PCI: hv: Fix a race condition when removing the device")

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: "Krzysztof Wilczyński" <kw@linux.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/linux-hyperv/20210823152130.GA21501@kili/
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/1630365207-20616-1-git-send-email-longli@linuxonhyperv.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index a53bd87..fc1a29a 100644 (file)
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3229,9 +3229,17 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
                return 0;
 
        if (!keep_devs) {
-               /* Delete any children which might still exist. */
+               struct list_head removed;
+
+               /* Move all present children to the list on stack */
+               INIT_LIST_HEAD(&removed);
                spin_lock_irqsave(&hbus->device_list_lock, flags);
-               list_for_each_entry_safe(hpdev, tmp, &hbus->children, list_entry) {
+               list_for_each_entry_safe(hpdev, tmp, &hbus->children, list_entry)
+                       list_move_tail(&hpdev->list_entry, &removed);
+               spin_unlock_irqrestore(&hbus->device_list_lock, flags);
+
+               /* Remove all children in the list */
+               list_for_each_entry_safe(hpdev, tmp, &removed, list_entry) {
                        list_del(&hpdev->list_entry);
                        if (hpdev->pci_slot)
                                pci_destroy_slot(hpdev->pci_slot);
@@ -3239,7 +3247,6 @@ static int hv_pci_bus_exit(struct hv_device *hdev, bool keep_devs)
                        put_pcichild(hpdev);
                        put_pcichild(hpdev);
                }
-               spin_unlock_irqrestore(&hbus->device_list_lock, flags);
        }
 
        ret = hv_send_resources_released(hdev);