Hi all,

A recent patch merged to 5.14 in the Broadcom RDMA driver  to call
pci_enable_atomic_ops_to_root crashes the host while creating VFs. The
crash is seen when pci_enable_atomic_ops_to_root is called with
a VF pci device.  pdev->bus->self is NULL.  Is this expected for VF?

Here is the stack trace for your reference.
crash> bt
PID: 4481   TASK: ffff89c6941b0000  CPU: 53  COMMAND: "bash"
 #0 [ffff9a94817136d8] machine_kexec at ffffffffb90601a4
 #1 [ffff9a9481713728] __crash_kexec at ffffffffb9190d5d
 #2 [ffff9a94817137f0] crash_kexec at ffffffffb9191c4d
 #3 [ffff9a9481713808] oops_end at ffffffffb9025cd6
 #4 [ffff9a9481713828] page_fault_oops at ffffffffb906e417
 #5 [ffff9a9481713888] exc_page_fault at ffffffffb9a0ad14
 #6 [ffff9a94817138b0] asm_exc_page_fault at ffffffffb9c00ace
    [exception RIP: pcie_capability_read_dword+28]
    RIP: ffffffffb952fd5c  RSP: ffff9a9481713960  RFLAGS: 00010246
    RAX: 0000000000000001  RBX: ffff89c6b1096000  RCX: 0000000000000000
    RDX: ffff9a9481713990  RSI: 0000000000000024  RDI: 0000000000000000
    RBP: 0000000000000080   R8: 0000000000000008   R9: ffff89c64341a2f8
    R10: 0000000000000002  R11: 0000000000000000  R12: ffff89c648bab000
    R13: 0000000000000000  R14: 0000000000000000  R15: ffff89c648bab0c8
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #7 [ffff9a9481713988] pci_enable_atomic_ops_to_root at ffffffffb95359a6
 #8 [ffff9a94817139c0] bnxt_qplib_determine_atomics at
ffffffffc08c1a33 [bnxt_re]
 #9 [ffff9a94817139d0] bnxt_re_dev_init at ffffffffc08ba2d1 [bnxt_re]
#10 [ffff9a9481713a78] bnxt_re_netdev_event at ffffffffc08bab8f [bnxt_re]
#11 [ffff9a9481713aa8] raw_notifier_call_chain at ffffffffb9102cbe
#12 [ffff9a9481713ad0] register_netdevice at ffffffffb9803ff3
#13 [ffff9a9481713b08] register_netdev at ffffffffb980410a
#14 [ffff9a9481713b18] bnxt_init_one at ffffffffc0349572 [bnxt_en]
#15 [ffff9a9481713b70] local_pci_probe at ffffffffb953b92f
#16 [ffff9a9481713ba0] pci_device_probe at ffffffffb953cf8f
#17 [ffff9a9481713be8] really_probe at ffffffffb9659619
#18 [ffff9a9481713c08] __driver_probe_device at ffffffffb96598fb
#19 [ffff9a9481713c28] driver_probe_device at ffffffffb965998f
#20 [ffff9a9481713c48] __device_attach_driver at ffffffffb9659cd2
#21 [ffff9a9481713c70] bus_for_each_drv at ffffffffb9657307
#22 [ffff9a9481713ca8] __device_attach at ffffffffb96593e0
#23 [ffff9a9481713ce8] pci_bus_add_device at ffffffffb9530b7a
#24 [ffff9a9481713d00] pci_iov_add_virtfn at ffffffffb955b1ca
#25 [ffff9a9481713d40] sriov_enable at ffffffffb955b54b
#26 [ffff9a9481713d90] bnxt_sriov_configure at ffffffffc034d913 [bnxt_en]
#27 [ffff9a9481713dd8] sriov_numvfs_store at ffffffffb955acb4
#28 [ffff9a9481713e10] kernfs_fop_write_iter at ffffffffb93f09ad
#29 [ffff9a9481713e48] new_sync_write at ffffffffb933b82c
#30 [ffff9a9481713ed0] vfs_write at ffffffffb933db64
#31 [ffff9a9481713f00] ksys_write at ffffffffb933dd99
#32 [ffff9a9481713f38] do_syscall_64 at ffffffffb9a07897
#33 [ffff9a9481713f50] entry_SYSCALL_64_after_hwframe at ffffffffb9c0007c
    RIP: 00007f450602f648  RSP: 00007ffe880869e8  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000002  RCX: 00007f450602f648
    RDX: 0000000000000002  RSI: 0000555c566c4a60  RDI: 0000000000000001
    RBP: 0000555c566c4a60   R8: 000000000000000a   R9: 00007f45060c2580
    R10: 000000000000000a  R11: 0000000000000246  R12: 00007f45063026e0
    R13: 0000000000000002  R14: 00007f45062fd880  R15: 0000000000000002
    ORIG_RAX: 0000000000000001  CS: 0033  SS: 002b

Please suggest a fix for solving this issue. Is adding a NULL check
for bus->self sounds okay?

Thanks,
Selvin