[PATCH 5.10 015/157] s390/pci: fix leak of PCI device structure

Greg Kroah-Hartman
2021-03-22T12:41:24Z

From: Niklas Schnelle <schnelle@linux.ibm.com>

commit 0b13525c20febcfecccf6fc1db5969727401317d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/s390/include/asm/pci.h | 2 +-
arch/s390/pci/pci.c | 28 ++++++++++++++++++++++++----
arch/s390/pci/pci_event.c | 18 ++++++------------
drivers/pci/hotplug/s390_pci_hpc.c | 3 ++-
4 files changed, 33 insertions(+), 18 deletions(-)

--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -202,7 +202,7 @@ extern unsigned int s390_pci_no_rid;
----------------------------------------------------------------------------- */
/* Base stuff */
int zpci_create_device(u32 fid, u32 fh, enum zpci_state state);
-void zpci_remove_device(struct zpci_dev *zdev);
+void zpci_remove_device(struct zpci_dev *zdev, bool set_error);
int zpci_enable_device(struct zpci_dev *);
int zpci_disable_device(struct zpci_dev *);
int zpci_register_ioat(struct zpci_dev *, u8, u64, u64, u64);
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -682,16 +682,36 @@ int zpci_disable_device(struct zpci_dev
}
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 *kr
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:
--- 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(st
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(st
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);
--- a/drivers/pci/hotplug/s390_pci_hpc.c
+++ b/drivers/pci/hotplug/s390_pci_hpc.c
@@ -93,8 +93,9 @@ static int disable_slot(struct hotplug_s
pci_dev_put(pdev);
return -EBUSY;
}
+ pci_dev_put(pdev);

- zpci_remove_device(zdev);
+ zpci_remove_device(zdev, false);

rc = zpci_disable_device(zdev);
if (rc)