s390/pci: fix leak of PCI device structure

In commit 05bc1be6db4b2 ("s390/pci: create zPCI bus") we removed the
pci_dev_put() call matching the earlier pci_get_slot() done as part of
__zpci_event_availability(). This was based on the wrong understanding
that the device_put() done as part of pci_destroy_device() would counter
the pci_get_slot() when it only counters the initial reference. This
same understanding and existing bad example also lead to not doing
a pci_dev_put() in zpci_remove_device().

Since releasing the PCI devices, unlike releasing the PCI slot, does not
print any debug message for testing I added one in pci_release_dev().
This revealed that we are indeed leaking the PCI device on PCI
hotunplug. Further testing also revealed another missing pci_dev_put() in
disable_slot().

Fix this by adding the missing pci_dev_put() in disable_slot() and fix
zpci_remove_device() with the correct pci_dev_put() calls. Also instead
of calling pci_get_slot() in __zpci_event_availability() to determine if
a PCI device is registered and then doing the same again in
zpci_remove_device() do this once in zpci_remove_device() which makes
sure that the pdev in __zpci_event_availability() is only used for the
result of pci_scan_single_device() which does not need a reference count
decremnt as its ownership goes to the PCI bus.

Also move the check if zdev->zbus->bus is set into zpci_remove_device()
since it may be that we're removing a device with devfn != 0 which never
had a PCI bus. So we can still set the pdev->error_state to indicate
that the device is not usable anymore, add a flag to set the error state.

Fixes: 05bc1be6db4b2 ("s390/pci: create zPCI bus")
Cc: <stable@vger.kernel.org> # 5.8+: e1bff843cde6 s390/pci: remove superfluous zdev->zbus check
Cc: <stable@vger.kernel.org> # 5.8+: ba764dd703fe s390/pci: refactor zpci_create_device()
Cc: <stable@vger.kernel.org> # 5.8+
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 600881d894dd..91064077526d 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -682,16 +682,36 @@ int zpci_disable_device(struct zpci_dev *zdev)
 }
 EXPORT_SYMBOL_GPL(zpci_disable_device);
 
-void zpci_remove_device(struct zpci_dev *zdev)
+/* zpci_remove_device - Removes the given zdev from the PCI core
+ * @zdev: the zdev to be removed from the PCI core
+ * @set_error: if true the device's error state is set to permanent failure
+ *
+ * Sets a zPCI device to a configured but offline state; the zPCI
+ * device is still accessible through its hotplug slot and the zPCI
+ * API but is removed from the common code PCI bus, making it
+ * no longer available to drivers.
+ */
+void zpci_remove_device(struct zpci_dev *zdev, bool set_error)
 {
 	struct zpci_bus *zbus = zdev->zbus;
 	struct pci_dev *pdev;
 
+	if (!zdev->zbus->bus)
+		return;
+
 	pdev = pci_get_slot(zbus->bus, zdev->devfn);
 	if (pdev) {
-		if (pdev->is_virtfn)
-			return zpci_iov_remove_virtfn(pdev, zdev->vfn);
+		if (set_error)
+			pdev->error_state = pci_channel_io_perm_failure;
+		if (pdev->is_virtfn) {
+			zpci_iov_remove_virtfn(pdev, zdev->vfn);
+			/* balance pci_get_slot */
+			pci_dev_put(pdev);
+			return;
+		}
 		pci_stop_and_remove_bus_device_locked(pdev);
+		/* balance pci_get_slot */
+		pci_dev_put(pdev);
 	}
 }
 
@@ -765,7 +785,7 @@ void zpci_release_device(struct kref *kref)
 	struct zpci_dev *zdev = container_of(kref, struct zpci_dev, kref);
 
 	if (zdev->zbus->bus)
-		zpci_remove_device(zdev);
+		zpci_remove_device(zdev, false);
 
 	switch (zdev->state) {
 	case ZPCI_FN_STATE_ONLINE: