igb: NULL pointer dereference

[Alex Williamson <alex.williamson@redhat.com>]

On Linus' current tree I get the the oops below.  I realize I'm still
using the deprecated max_vfs= module option, but this isn't a very
compatible or friendly migration path.  I'm using an 82576 PF as an
interface for connecting an iscsi root disk and I also use the VF off
this interface for misc virtual machine assignment.  Suggestions welcome
on migrating to sysfs based sr-iov enabling from an initramfs without
bouncing the PF interface, but I think the below needs to be fixed
regardless.  git bisected to:

commit fa44f2f185f7f9da19d331929bb1b56c1ccd1d93
Author: Greg Rose <gregory.v.rose@intel.com>
Date:   Thu Jan 17 01:03:06 2013 -0800

    igb: Enable SR-IOV configuration via PCI sysfs interface
    
    Implement callback in the driver for the new PCI bus driver
    interface that allows the user to enable/disable SR-IOV
    virtual functions in a device via the sysfs interface.
    
    Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
    Tested-by: Aaron Brown <aaron.f.brown@intel.com>
    Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Thanks,

Alex


[    4.831907] igb: Intel(R) Gigabit Ethernet Network Driver - version 4.1.2-k
[    4.838868] igb: Copyright (c) 2007-2012 Intel Corporation.
[    4.844710] igb 0000:01:00.0: Maximum of 7 VFs per PF, using max
[    4.850768] igb 0000:01:00.0: Enabling SR-IOV VFs using the module parameter is deprecated - please use the pci sysfs interface.
[    4.872310] systemd[1]: Starting dracut initqueue hook...
         Startin[    4.877937] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
[    4.887143] IP: [<ffffffffa015862d>] igb_reset+0xcd/0x460 [igb]
[    4.893175] PGD 0 
[    4.895267] Oops: 0002 [#1] SMP 
[    4.898666] Modules linked in: igb(+) ptp usb_storage pps_core iscsi_tcp be2iscsi bnx2i cnic uio cxgb4i cxgb4 cxgb3i cxgb3 mdio libcxgbi libiscsi_tcp qla4xxx iscsi_boot_sysfs libiscsi scsi_transport_iscsi
[    4.918125] CPU 2 
[    4.919959] Pid: 207, comm: systemd-udevd Not tainted 3.8.0-rc3+ #278 LENOVO 4157CTO/LENOVO
[    4.928541] RIP: 0010:[<ffffffffa015862d>]  [<ffffffffa015862d>] igb_reset+0xcd/0x460 [igb]
[    4.937039] RSP: 0018:ffff880367f63b38  EFLAGS: 00010246
[    4.942409] RAX: 00000000000000ff RBX: ffff880367020800 RCX: 0000000000000001
[    4.949601] RDX: 0000000000000000 RSI: 0000000000000202 RDI: ffff880367020800
[    4.956803] RBP: ffff880367f63b58 R08: ffff88036814d408 R09: 0000000000000007
[    4.964004] R10: ffffffff813eea13 R11: 000000000000000f R12: ffff880367020d68
[    4.971205] R13: ffff880371267000 R14: 0000000000000040 R15: ffff880367020000
[    4.978398] FS:  00007fdebfc3b840(0000) GS:ffff88037fc80000(0000) knlGS:0000000000000000
[    4.986549] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    4.992369] CR2: 0000000000000048 CR3: 0000000367df3000 CR4: 00000000000007e0
[    4.999649] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    5.006893] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[    5.014136] Process systemd-udevd (pid: 207, threadinfo ffff880367f62000, task ffff880367fa0000)
[    5.023108] Stack:
[    5.025280]  ffff880371267000 ffff880371267098 ffff880371267000 0000000000000001
[    5.033327]  ffff880367f63bd8 ffffffffa01593e5 ffff880371267098 ffff880367020d68
[    5.041400]  0000000000020000 ffff880367020800 0000000000000004 ffff880300007136
[    5.049451] Call Trace:
[    5.052050]  [<ffffffffa01593e5>] igb_probe+0x855/0xde0 [igb]
[    5.058023]  [<ffffffff8131eddb>] local_pci_probe+0x4b/0x80
[    5.063925]  [<ffffffff8131f0e1>] pci_device_probe+0x111/0x120
[    5.070082]  [<ffffffff813e4c1b>] driver_probe_device+0x8b/0x390
[    5.076375]  [<ffffffff813e4fcb>] __driver_attach+0xab/0xb0
[    5.082303]  [<ffffffff813e4f20>] ? driver_probe_device+0x390/0x390
[    5.088736]  [<ffffffff813e2ca5>] bus_for_each_dev+0x55/0x90
[    5.094458]  [<ffffffff813e458e>] driver_attach+0x1e/0x20
[    5.099921]  [<ffffffff813e41c0>] bus_add_driver+0x1a0/0x290
[    5.105691]  [<ffffffffa0180000>] ? 0xffffffffa017ffff
[    5.110937]  [<ffffffffa0180000>] ? 0xffffffffa017ffff
[    5.116305]  [<ffffffff813e5697>] driver_register+0x77/0x170
[    5.122287]  [<ffffffffa0180000>] ? 0xffffffffa017ffff
[    5.127786]  [<ffffffff8131e0ab>] __pci_register_driver+0x4b/0x50
[    5.134004]  [<ffffffffa018004f>] igb_init_module+0x4f/0x1000 [igb]
[    5.140565]  [<ffffffff8100215a>] do_one_initcall+0x12a/0x180
[    5.146321]  [<ffffffff810c3f3a>] load_module+0x1a8a/0x20c0
[    5.152020]  [<ffffffff8130f0a0>] ? ddebug_proc_open+0xc0/0xc0
[    5.157914]  [<ffffffff810c4647>] sys_init_module+0xd7/0x120
[    5.163639]  [<ffffffff81650ed9>] system_call_fastpath+0x16/0x1b
[    5.169702] Code: 83 e9 10 45 85 c9 89 8b 14 08 00 00 74 4d 31 c9 66 0f 1f 44 00 00 48 63 d1 83 c1 01 48 8d 14 52 48 c1 e2 05 48 03 93 98 0e 00 00 <83> 62 48 08 3b 8b 94 0e 00 00 72 df 48 89 df e8 2f da ff ff 48 
[    5.192637] RIP  [<ffffffffa015862d>] igb_reset+0xcd/0x460 [igb]
g dracut initque[    5.198783]  RSP <ffff880367f63b38>
[    5.203660] CR2: 0000000000000048
ue hook...
[    5.207169] ---[ end trace 494789df673e4a4c ]---