[PATCH] drm/xe/pf: Take pci_rescan_remove_lock mutex when disabling VFs

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

Since recent commit a5338e365c45 ("PCI/IOV: Fix race between SR-IOV
enable/disable and hotplug") the driver pci_driver.sriov_configure
hook is called with the mutex pci_rescan_remove_lock already taken.

As we are using this hook as-is during driver removal, we get:

 [ ] xe 0000:4d:00.0: [drm:xe_pci_sriov_configure [xe]] PF: disabling 1 VF
 [ ] ------------[ cut here ]------------
 [ ] debug_locks && !(lock_is_held(&(&pci_rescan_remove_lock)->dep_map) != 0)
 [ ] WARNING: drivers/pci/remove.c:130 at pci_stop_and_remove_bus_device+0x4c/0x50, CPU#32: rmmod/6476
 [ ] RIP: 0010:pci_stop_and_remove_bus_device+0x4c/0x50
 [ ] Call Trace:
 [ ]  <TASK>
 [ ]  pci_iov_remove_virtfn+0xd1/0x140
 [ ]  sriov_disable+0x42/0x100
 [ ]  pci_disable_sriov+0x34/0x50
 [ ]  xe_pci_sriov_configure+0x2d0/0x1150 [xe]
 [ ]  xe_pci_remove+0x7c/0x190 [xe]
 [ ]  pci_device_remove+0x41/0xb0
 [ ]  device_remove+0x43/0x80
 [ ]  device_release_driver_internal+0x215/0x280
 [ ]  driver_detach+0x50/0xb0
 [ ]  bus_remove_driver+0x86/0x120
 [ ]  driver_unregister+0x2f/0x60
 [ ]  pci_unregister_driver+0x22/0xc0
 [ ]  xe_unregister_pci_driver+0x15/0x20 [xe]
 [ ]  xe_exit+0x1f/0x34 [xe]

Fix that by taking a pci_rescan_remove_lock as it is now expected.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
---
 drivers/gpu/drm/xe/xe_pci.c       |  2 +-
 drivers/gpu/drm/xe/xe_pci_sriov.c | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index 3ac99472d6dd..fb0abd768e67 100644
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -1010,7 +1010,7 @@ static void xe_pci_remove(struct pci_dev *pdev)
 	struct xe_device *xe = pdev_to_xe_device(pdev);
 
 	if (IS_SRIOV_PF(xe))
-		xe_pci_sriov_configure(pdev, 0);
+		xe_pci_sriov_disable_vfs(pdev);
 
 	if (xe_survivability_mode_is_boot_enabled(xe))
 		return;
diff --git a/drivers/gpu/drm/xe/xe_pci_sriov.c b/drivers/gpu/drm/xe/xe_pci_sriov.c
index 3fd22034f03e..2a3fd3578ef2 100644
--- a/drivers/gpu/drm/xe/xe_pci_sriov.c
+++ b/drivers/gpu/drm/xe/xe_pci_sriov.c
@@ -239,6 +239,26 @@ int xe_pci_sriov_configure(struct pci_dev *pdev, int num_vfs)
 		return pf_disable_vfs(xe);
 }
 
+/**
+ * xe_pci_sriov_disable_vfs() - Disable all VFs.
+ * @pdev: the PF's &pci_dev
+ *
+ * This is a simple wrapper around our function that implements the
+ * pci_driver.sriov_configure hook but also takes a required mutex.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int xe_pci_sriov_disable_vfs(struct pci_dev *pdev)
+{
+	int ret;
+
+	pci_lock_rescan_remove();
+	ret = xe_pci_sriov_configure(pdev, 0);
+	pci_unlock_rescan_remove();
+
+	return ret;
+}
+
 /**
  * xe_pci_sriov_get_vf_pdev() - Lookup the VF's PCI device using the VF identifier.
  * @pdev: the PF's &pci_dev
-- 
2.47.1