s390/pci: handle events for unused functions

Receiving error events for a pci function that's currently not in use
will crash the kernel. For example the procedure for FW upgrades might
include:
* remove the function from Linux
* apply FW upgrade
* rescan for new functions

Receiving an event during the FW upgrade will result in a use after free
when printing the functions name. Just print "n/a" in such cases.

Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
index ed2394dd14e92faf57ac34b63ef49731f08ade68..eef76f0e68731ce4b5a7a8244c030fa8de6447bf 100644 (file)
--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -46,15 +46,13 @@ struct zpci_ccdf_avail {
 static void __zpci_event_error(struct zpci_ccdf_err *ccdf)
 {
        struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid);
+       struct pci_dev *pdev = zdev ? zdev->pdev : NULL;
 
        zpci_err("error CCDF:\n");
        zpci_err_hex(ccdf, sizeof(*ccdf));
 
-       if (!zdev)
-               return;
-
        pr_err("%s: Event 0x%x reports an error for PCI function 0x%x\n",
-              pci_name(zdev->pdev), ccdf->pec, ccdf->fid);
+              pdev ? pci_name(pdev) : "n/a", ccdf->pec, ccdf->fid);
 }
 
 void zpci_event_error(void *data)