tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
master
head:   65f0d2414b7079556fbbcc070b3d1c9f9587606d
commit: 3047766bc6ec9c6bc9ece85b45a41ff401e8d988 s390/pci: fix enabling a 
reserved PCI function
config: s390-randconfig-m031-20210114 (attached as .config)
compiler: s390-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>

smatch warnings:
arch/s390/pci/pci_event.c:101 __zpci_event_availability() error: we previously 
assumed 'zdev->zbus' could be null (see line 83)

vim +101 arch/s390/pci/pci_event.c

aa3b7c296732b4 Sebastian Ott   2013-12-12   76  static void 
__zpci_event_availability(struct zpci_ccdf_avail *ccdf)
cbc0dd1f856b52 Jan Glauber     2012-11-29   77  {
cbc0dd1f856b52 Jan Glauber     2012-11-29   78          struct zpci_dev *zdev = 
get_zdev_by_fid(ccdf->fid);
9a99649f2a89fd Sebastian Ott   2016-01-29   79          struct pci_dev *pdev = 
NULL;
623bd44d3f277b Sebastian Ott   2017-05-09   80          enum zpci_state state;
d795ddad36cbc8 Sebastian Ott   2013-11-15   81          int ret;
cbc0dd1f856b52 Jan Glauber     2012-11-29   82  
05bc1be6db4b26 Pierre Morel    2020-03-23  @83          if (zdev && zdev->zbus 
&& zdev->zbus->bus)
                                                                    ^^^^^^^^^^
Can this be NULL?

44510d6fa0c00a Pierre Morel    2020-04-22   84                  pdev = 
pci_get_slot(zdev->zbus->bus, zdev->devfn);
9a99649f2a89fd Sebastian Ott   2016-01-29   85  
1f1dcbd4f23bd1 Sebastian Ott   2013-10-22   86          zpci_err("avail 
CCDF:\n");
1f1dcbd4f23bd1 Sebastian Ott   2013-10-22   87          zpci_err_hex(ccdf, 
sizeof(*ccdf));
cbc0dd1f856b52 Jan Glauber     2012-11-29   88  
cbc0dd1f856b52 Jan Glauber     2012-11-29   89          switch (ccdf->pec) {
7fc611ff3ff1a0 Sebastian Ott   2015-06-16   90          case 0x0301: /* 
Reserved|Standby -> Configured */
7fc611ff3ff1a0 Sebastian Ott   2015-06-16   91                  if (!zdev) {
f606b3ef47c9f8 Pierre Morel    2020-03-25   92                          ret = 
clp_add_pci_device(ccdf->fid, ccdf->fh, 1);
7fc611ff3ff1a0 Sebastian Ott   2015-06-16   93                          break;
7fc611ff3ff1a0 Sebastian Ott   2015-06-16   94                  }
fcf2f402937a66 Sebastian Ott   2013-12-18   95                  zdev->fh = 
ccdf->fh;
f606b3ef47c9f8 Pierre Morel    2020-03-25   96                  zdev->state = 
ZPCI_FN_STATE_CONFIGURED;
3047766bc6ec9c Niklas Schnelle 2020-06-18   97                  ret = 
zpci_enable_device(zdev);
3047766bc6ec9c Niklas Schnelle 2020-06-18   98                  if (ret)
3047766bc6ec9c Niklas Schnelle 2020-06-18   99                          break;
3047766bc6ec9c Niklas Schnelle 2020-06-18  100  
3047766bc6ec9c Niklas Schnelle 2020-06-18 @101                  pdev = 
pci_scan_single_device(zdev->zbus->bus, zdev->devfn);
                                                                                
              ^^^^^^^^^^^^^^^
Unchecked dereference

3047766bc6ec9c Niklas Schnelle 2020-06-18  102                  if (!pdev)
3047766bc6ec9c Niklas Schnelle 2020-06-18  103                          break;
3047766bc6ec9c Niklas Schnelle 2020-06-18  104  
3047766bc6ec9c Niklas Schnelle 2020-06-18  105                  
pci_bus_add_device(pdev);
3047766bc6ec9c Niklas Schnelle 2020-06-18  106                  
pci_lock_rescan_remove();
3047766bc6ec9c Niklas Schnelle 2020-06-18  107                  
pci_bus_add_devices(zdev->zbus->bus);
3047766bc6ec9c Niklas Schnelle 2020-06-18  108                  
pci_unlock_rescan_remove();
cbc0dd1f856b52 Jan Glauber     2012-11-29  109                  break;
d795ddad36cbc8 Sebastian Ott   2013-11-15  110          case 0x0302: /* 
Reserved -> Standby */
f606b3ef47c9f8 Pierre Morel    2020-03-25  111                  if (!zdev) {
d795ddad36cbc8 Sebastian Ott   2013-11-15  112                          
clp_add_pci_device(ccdf->fid, ccdf->fh, 0);
cbc0dd1f856b52 Jan Glauber     2012-11-29  113                          break;
f606b3ef47c9f8 Pierre Morel    2020-03-25  114                  }
f606b3ef47c9f8 Pierre Morel    2020-03-25  115                  zdev->fh = 
ccdf->fh;
f606b3ef47c9f8 Pierre Morel    2020-03-25  116                  break;
d795ddad36cbc8 Sebastian Ott   2013-11-15  117          case 0x0303: /* 
Deconfiguration requested */
623bd44d3f277b Sebastian Ott   2017-05-09  118                  if (!zdev)
623bd44d3f277b Sebastian Ott   2017-05-09  119                          break;
d795ddad36cbc8 Sebastian Ott   2013-11-15  120                  if (pdev)
2a01bd1bd3d28d Sebastian Ott   2015-07-28  121                          
pci_stop_and_remove_bus_device_locked(pdev);
cbc0dd1f856b52 Jan Glauber     2012-11-29  122  
d795ddad36cbc8 Sebastian Ott   2013-11-15  123                  ret = 
zpci_disable_device(zdev);
d795ddad36cbc8 Sebastian Ott   2013-11-15  124                  if (ret)
d795ddad36cbc8 Sebastian Ott   2013-11-15  125                          break;
1f1dcbd4f23bd1 Sebastian Ott   2013-10-22  126  
d795ddad36cbc8 Sebastian Ott   2013-11-15  127                  ret = 
sclp_pci_deconfigure(zdev->fid);
d795ddad36cbc8 Sebastian Ott   2013-11-15  128                  zpci_dbg(3, 
"deconf fid:%x, rc:%d\n", zdev->fid, ret);
d795ddad36cbc8 Sebastian Ott   2013-11-15  129                  if (!ret)
d795ddad36cbc8 Sebastian Ott   2013-11-15  130                          
zdev->state = ZPCI_FN_STATE_STANDBY;
cbc0dd1f856b52 Jan Glauber     2012-11-29  131  
d795ddad36cbc8 Sebastian Ott   2013-11-15  132                  break;
623bd44d3f277b Sebastian Ott   2017-05-09  133          case 0x0304: /* 
Configured -> Standby|Reserved */
623bd44d3f277b Sebastian Ott   2017-05-09  134                  if (!zdev)
623bd44d3f277b Sebastian Ott   2017-05-09  135                          break;
0c0c2776926018 Sebastian Ott   2013-12-12  136                  if (pdev) {
0c0c2776926018 Sebastian Ott   2013-12-12  137                          /* Give 
the driver a hint that the function is
0c0c2776926018 Sebastian Ott   2013-12-12  138                           * 
already unusable. */
0c0c2776926018 Sebastian Ott   2013-12-12  139                          
pdev->error_state = pci_channel_io_perm_failure;
2a01bd1bd3d28d Sebastian Ott   2015-07-28  140                          
pci_stop_and_remove_bus_device_locked(pdev);
0c0c2776926018 Sebastian Ott   2013-12-12  141                  }
1f1dcbd4f23bd1 Sebastian Ott   2013-10-22  142  
d795ddad36cbc8 Sebastian Ott   2013-11-15  143                  zdev->state = 
ZPCI_FN_STATE_STANDBY;
623bd44d3f277b Sebastian Ott   2017-05-09  144                  if 
(!clp_get_state(ccdf->fid, &state) &&
623bd44d3f277b Sebastian Ott   2017-05-09  145                      state == 
ZPCI_FN_STATE_RESERVED) {
05bc1be6db4b26 Pierre Morel    2020-03-23  146                          
zpci_zdev_put(zdev);
623bd44d3f277b Sebastian Ott   2017-05-09  147                  }
d795ddad36cbc8 Sebastian Ott   2013-11-15  148                  break;
d795ddad36cbc8 Sebastian Ott   2013-11-15  149          case 0x0306: /* 0x308 
or 0x302 for multiple devices */
d795ddad36cbc8 Sebastian Ott   2013-11-15  150                  
clp_rescan_pci_devices();
d795ddad36cbc8 Sebastian Ott   2013-11-15  151                  break;
d795ddad36cbc8 Sebastian Ott   2013-11-15  152          case 0x0308: /* Standby 
-> Reserved */
704268925d32a0 Sebastian Ott   2013-12-12  153                  if (!zdev)
704268925d32a0 Sebastian Ott   2013-12-12  154                          break;
05bc1be6db4b26 Pierre Morel    2020-03-23  155                  
zpci_zdev_put(zdev);
d795ddad36cbc8 Sebastian Ott   2013-11-15  156                  break;
d795ddad36cbc8 Sebastian Ott   2013-11-15  157          default:
d795ddad36cbc8 Sebastian Ott   2013-11-15  158                  break;
cbc0dd1f856b52 Jan Glauber     2012-11-29  159          }
cbc0dd1f856b52 Jan Glauber     2012-11-29  160  }

---
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