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

From: Dan Carpenter
Date: Thu Dec 03 2020 - 05:29:22 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 3bb61aa61828499a7d0f5e560051625fd02ae7e4
commit: 3047766bc6ec9c6bc9ece85b45a41ff401e8d988 s390/pci: fix enabling a reserved PCI function

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

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

aa3b7c296732b43 Sebastian Ott 2013-12-12 76 static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
cbc0dd1f856b52b Jan Glauber 2012-11-29 77 {
cbc0dd1f856b52b Jan Glauber 2012-11-29 78 struct zpci_dev *zdev = get_zdev_by_fid(ccdf->fid);
9a99649f2a89fdf Sebastian Ott 2016-01-29 79 struct pci_dev *pdev = NULL;
623bd44d3f277b7 Sebastian Ott 2017-05-09 80 enum zpci_state state;
d795ddad36cbc82 Sebastian Ott 2013-11-15 81 int ret;
cbc0dd1f856b52b Jan Glauber 2012-11-29 82
05bc1be6db4b268 Pierre Morel 2020-03-23 @83 if (zdev && zdev->zbus && zdev->zbus->bus)
^^^^^^^^^
Check for NULL

44510d6fa0c00aa Pierre Morel 2020-04-22 84 pdev = pci_get_slot(zdev->zbus->bus, zdev->devfn);
9a99649f2a89fdf Sebastian Ott 2016-01-29 85
1f1dcbd4f23bd1f Sebastian Ott 2013-10-22 86 zpci_err("avail CCDF:\n");
1f1dcbd4f23bd1f Sebastian Ott 2013-10-22 87 zpci_err_hex(ccdf, sizeof(*ccdf));
cbc0dd1f856b52b Jan Glauber 2012-11-29 88
cbc0dd1f856b52b Jan Glauber 2012-11-29 89 switch (ccdf->pec) {
7fc611ff3ff1a0b Sebastian Ott 2015-06-16 90 case 0x0301: /* Reserved|Standby -> Configured */
7fc611ff3ff1a0b Sebastian Ott 2015-06-16 91 if (!zdev) {
f606b3ef47c9f87 Pierre Morel 2020-03-25 92 ret = clp_add_pci_device(ccdf->fid, ccdf->fh, 1);
7fc611ff3ff1a0b Sebastian Ott 2015-06-16 93 break;
7fc611ff3ff1a0b Sebastian Ott 2015-06-16 94 }
fcf2f402937a669 Sebastian Ott 2013-12-18 95 zdev->fh = ccdf->fh;
f606b3ef47c9f87 Pierre Morel 2020-03-25 96 zdev->state = ZPCI_FN_STATE_CONFIGURED;
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 97 ret = zpci_enable_device(zdev);
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 98 if (ret)
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 99 break;
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 100
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 @101 pdev = pci_scan_single_device(zdev->zbus->bus, zdev->devfn);
^^^^^^^^^^^^^^^^
Unchecked dereference

3047766bc6ec9c6 Niklas Schnelle 2020-06-18 102 if (!pdev)
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 103 break;
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 104
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 105 pci_bus_add_device(pdev);
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 106 pci_lock_rescan_remove();
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 107 pci_bus_add_devices(zdev->zbus->bus);
3047766bc6ec9c6 Niklas Schnelle 2020-06-18 108 pci_unlock_rescan_remove();
cbc0dd1f856b52b Jan Glauber 2012-11-29 109 break;
d795ddad36cbc82 Sebastian Ott 2013-11-15 110 case 0x0302: /* Reserved -> Standby */
f606b3ef47c9f87 Pierre Morel 2020-03-25 111 if (!zdev) {
d795ddad36cbc82 Sebastian Ott 2013-11-15 112 clp_add_pci_device(ccdf->fid, ccdf->fh, 0);
cbc0dd1f856b52b Jan Glauber 2012-11-29 113 break;
f606b3ef47c9f87 Pierre Morel 2020-03-25 114 }
f606b3ef47c9f87 Pierre Morel 2020-03-25 115 zdev->fh = ccdf->fh;
f606b3ef47c9f87 Pierre Morel 2020-03-25 116 break;
d795ddad36cbc82 Sebastian Ott 2013-11-15 117 case 0x0303: /* Deconfiguration requested */
623bd44d3f277b7 Sebastian Ott 2017-05-09 118 if (!zdev)
623bd44d3f277b7 Sebastian Ott 2017-05-09 119 break;
d795ddad36cbc82 Sebastian Ott 2013-11-15 120 if (pdev)
2a01bd1bd3d28d1 Sebastian Ott 2015-07-28 121 pci_stop_and_remove_bus_device_locked(pdev);
cbc0dd1f856b52b Jan Glauber 2012-11-29 122
d795ddad36cbc82 Sebastian Ott 2013-11-15 123 ret = zpci_disable_device(zdev);
d795ddad36cbc82 Sebastian Ott 2013-11-15 124 if (ret)
d795ddad36cbc82 Sebastian Ott 2013-11-15 125 break;
1f1dcbd4f23bd1f Sebastian Ott 2013-10-22 126
d795ddad36cbc82 Sebastian Ott 2013-11-15 127 ret = sclp_pci_deconfigure(zdev->fid);
d795ddad36cbc82 Sebastian Ott 2013-11-15 128 zpci_dbg(3, "deconf fid:%x, rc:%d\n", zdev->fid, ret);
d795ddad36cbc82 Sebastian Ott 2013-11-15 129 if (!ret)
d795ddad36cbc82 Sebastian Ott 2013-11-15 130 zdev->state = ZPCI_FN_STATE_STANDBY;
cbc0dd1f856b52b Jan Glauber 2012-11-29 131
d795ddad36cbc82 Sebastian Ott 2013-11-15 132 break;
623bd44d3f277b7 Sebastian Ott 2017-05-09 133 case 0x0304: /* Configured -> Standby|Reserved */
623bd44d3f277b7 Sebastian Ott 2017-05-09 134 if (!zdev)
623bd44d3f277b7 Sebastian Ott 2017-05-09 135 break;
0c0c2776926018e Sebastian Ott 2013-12-12 136 if (pdev) {
0c0c2776926018e Sebastian Ott 2013-12-12 137 /* Give the driver a hint that the function is
0c0c2776926018e Sebastian Ott 2013-12-12 138 * already unusable. */
0c0c2776926018e Sebastian Ott 2013-12-12 139 pdev->error_state = pci_channel_io_perm_failure;
2a01bd1bd3d28d1 Sebastian Ott 2015-07-28 140 pci_stop_and_remove_bus_device_locked(pdev);
0c0c2776926018e Sebastian Ott 2013-12-12 141 }
1f1dcbd4f23bd1f Sebastian Ott 2013-10-22 142
d795ddad36cbc82 Sebastian Ott 2013-11-15 143 zdev->state = ZPCI_FN_STATE_STANDBY;
623bd44d3f277b7 Sebastian Ott 2017-05-09 144 if (!clp_get_state(ccdf->fid, &state) &&
623bd44d3f277b7 Sebastian Ott 2017-05-09 145 state == ZPCI_FN_STATE_RESERVED) {
05bc1be6db4b268 Pierre Morel 2020-03-23 146 zpci_zdev_put(zdev);
623bd44d3f277b7 Sebastian Ott 2017-05-09 147 }
d795ddad36cbc82 Sebastian Ott 2013-11-15 148 break;
d795ddad36cbc82 Sebastian Ott 2013-11-15 149 case 0x0306: /* 0x308 or 0x302 for multiple devices */
d795ddad36cbc82 Sebastian Ott 2013-11-15 150 clp_rescan_pci_devices();
d795ddad36cbc82 Sebastian Ott 2013-11-15 151 break;
d795ddad36cbc82 Sebastian Ott 2013-11-15 152 case 0x0308: /* Standby -> Reserved */
704268925d32a04 Sebastian Ott 2013-12-12 153 if (!zdev)
704268925d32a04 Sebastian Ott 2013-12-12 154 break;
05bc1be6db4b268 Pierre Morel 2020-03-23 155 zpci_zdev_put(zdev);
d795ddad36cbc82 Sebastian Ott 2013-11-15 156 break;
d795ddad36cbc82 Sebastian Ott 2013-11-15 157 default:
d795ddad36cbc82 Sebastian Ott 2013-11-15 158 break;
cbc0dd1f856b52b Jan Glauber 2012-11-29 159 }
cbc0dd1f856b52b Jan Glauber 2012-11-29 160 }

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