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, 6 insertions, 12 deletions

diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
index b4162da4e8a2..ac0c65cdd69d 100644
--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -76,13 +76,10 @@ void zpci_event_error(void *data)
 static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 {
 	struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid);
-	struct pci_dev *pdev = NULL;
 	enum zpci_state state;
+	struct pci_dev *pdev;
 	int ret;
 
-	if (zdev && zdev->zbus->bus)
-		pdev = pci_get_slot(zdev->zbus->bus, zdev->devfn);
-
 	zpci_err("avail CCDF:\n");
 	zpci_err_hex(ccdf, sizeof(*ccdf));
 
@@ -124,8 +121,7 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 	case 0x0303: /* Deconfiguration requested */
 		if (!zdev)
 			break;
-		if (pdev)
-			zpci_remove_device(zdev);
+		zpci_remove_device(zdev, false);
 
 		ret = zpci_disable_device(zdev);
 		if (ret)
@@ -140,12 +136,10 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 	case 0x0304: /* Configured -> Standby|Reserved */
 		if (!zdev)
 			break;
-		if (pdev) {
-			/* Give the driver a hint that the function is
-			 * already unusable. */
-			pdev->error_state = pci_channel_io_perm_failure;
-			zpci_remove_device(zdev);
-		}
+		/* Give the driver a hint that the function is
+		 * already unusable.
+		 */
+		zpci_remove_device(zdev, true);
 
 		zdev->fh = ccdf->fh;
 		zpci_disable_device(zdev);