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s390/pci: remove superfluous zdev->zbus check

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commit e1bff843cd upstream.

Checking zdev->zbus for NULL in __zpci_event_availability() is
superfluous as it can never be NULL at this point. While harmless this
check causes smatch warnings because we later access zdev->zbus with
only having checked zdev != NULL which is sufficient.

The reason zdev->zbus can never be NULL is since with zdev != NULL given
we know the zdev came from get_zdev_by_fid() and thus the zpci_list.
Now on first glance at zpci_create_device() one may assume that there is
a window where the zdev is in the list without a zdev, however this
window can't overlap with __zpci_event_availability() as
zpci_create_device() either runs on the same kthread as part of
availability events, or during the initial CLP List PCI at which point
the __zpci_event_availability() is not yet called as zPCI is not yet
initialized.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Niklas Schnelle 2021-01-19 08:49:37 +01:00 committed by Greg Kroah-Hartman
parent bd37d9b9c4
commit 075e303474
1 changed files with 1 additions and 1 deletions
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2
arch/s390/pci/pci_event.c
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@ -80,7 +80,7 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
enum zpci_state state;
int ret;
if (zdev && zdev->zbus && zdev->zbus->bus)
if (zdev && zdev->zbus->bus)
pdev = pci_get_slot(zdev->zbus->bus, zdev->devfn);
zpci_err("avail CCDF:\n");