Re: [RESEND BUGFIX PATCH 1/3] PCI/AER: fix pci_ops return NULL when hotplug a pci bus which was doing aer error inject

[Jiang Liu <liuj97@xxxxxxxxx>]

Is it ok to ignore such a case? After all, aer_inject is just a test tool:)
It's not worth to change the core logic for such a corner case.
--Gerry

On 08/27/2012 09:23 AM, Huang Ying wrote:
> On Sat, 2012-08-25 at 17:59 +0800, Yijing Wang wrote:
>> When we inject aer errors to the target pci device by aer_inject module, the pci_ops of pci
>> bus which the target device is on will be assign to pci_ops_aer.So if the target pci device
>> is a bridge, once we hotplug the pci bus(child bus) which the target device bridges to, child
>> bus's pci_ops will be assigned to pci_ops_aer too.Now every access to the child bus's device
>> will result to system panic, because it return NULL pci_ops in pci_read_aer.
>> This patch fix this.
>>
>> CallTrace:
>> bash[5908]: NaT consumption 17179869216 [1]
>> Modules linked in: aer_inject cpufreq_conservative cpufreq_userspace cpufreq_pow
>> ersave acpi_cpufreq binfmt_misc fuse nls_iso8859_1 loop ipmi_si(+) ipmi_devintf
>> ipmi_msghandler dm_mod ppdev iTCO_wdt iTCO_vendor_support sg igb parport_pc i2c_
>> i801 mptctl i2c_core serio_raw hid_generic lpc_ich mfd_core parport button conta
>> iner usbhid hid uhci_hcd ehci_hcd usbcore usb_common sd_mod crc_t10dif ext3 mbca
>> che jbd fan processor ide_pci_generic ide_core ata_piix libata mptsas mptscsih m
>> ptbase scsi_transport_sas scsi_mod thermal thermal_sys hwmon
>>
>> Pid: 5908, CPU 9, comm:                 bash
>> psr : 00001010085a2010 ifs : 800000000000048e ip  : [<a000000220b815b0>]    Not
>> tainted (3.5.0-rc6yijing-repo)
>> ip is at pci_read_aer+0x330/0x460 [aer_inject]
>> unat: 0000000000000000 pfs : 000000000000048e rsc : 0000000000000003
>> rnat: 0000000000000000 bsps: 0000000000000000 pr  : 65519aa6a6969aa5
>> ldrs: 0000000000000000 ccv : ffffffff00000001 fpsr: 0009804c8a70033f
>> csd : 0000000000000000 ssd : 0000000000000000
>> b0  : a000000220b815b0 b6  : a000000220b81280 b7  : a0000001006d56a0
>> f6  : 1003e0000000000000005 f7  : 1003e0000000000000028
>> f8  : 1003e00000000000000c8 f9  : 1003e0000000000000005
>> f10 : 1003e627ec1e2f4c0d8a7 f11 : 1003e0000000000000011
>> r1  : a0000001014e63c0 r2  : 0000000000000738 r3  : 000000000000fffe
>> r8  : 0000000000000736 r9  : 0000000000000042 r10 : e000001f08f4c898
>> r11 : 0000000000000000 r12 : e000000f3dfcfdc0 r13 : e000000f3dfc0000
>> r14 : 0000000000000738 r15 : 0000000000004000 r16 : a000000220b827c8
>> r17 : a000000220b827b8 r18 : ffffffffffffff00 r19 : e000000f073b0110
>> r20 : 0000000000000042 r21 : e000000f073b0114 r22 : 0000000000000000
>> r23 : e000000f073b0118 r24 : a0000001009e0e49 r25 : 0000000000000001
>> r26 : 0000000000007041 r27 : e000000f3dfcfde0 r28 : 0000000000000000
>> r29 : e000000f3dfcfc08 r30 : a000000220b827c8 r31 : e000001f074d6000
>>
>> Call Trace:
>>  [<a000000100016500>] show_stack+0x80/0xa0
>>                                 sp=e000000f3dfcf800 bsp=e000000f3dfc1758
>>  [<a000000100016b60>] show_regs+0x640/0x920
>>                                 sp=e000000f3dfcf9d0 bsp=e000000f3dfc1700
>>  [<a000000100040770>] die+0x190/0x2c0
>>                                 sp=e000000f3dfcf9e0 bsp=e000000f3dfc16c0
>>  [<a0000001000408f0>] die_if_kernel+0x50/0x80
>>                                 sp=e000000f3dfcf9e0 bsp=e000000f3dfc1690
>>  [<a000000100903a90>] ia64_fault+0xf0/0x15e0
>>                                 sp=e000000f3dfcf9e0 bsp=e000000f3dfc1640
>>  [<a00000010000c0a0>] ia64_native_leave_kernel+0x0/0x270
>>                                 sp=e000000f3dfcfbf0 bsp=e000000f3dfc1640
>>  [<a000000220b815b0>] pci_read_aer+0x330/0x460 [aer_inject]
>>                                 sp=e000000f3dfcfdc0 bsp=e000000f3dfc15c8
>>  [<a0000001004ace00>] pci_bus_read_config_dword+0xe0/0x140
>>                                 sp=e000000f3dfcfdc0 bsp=e000000f3dfc1580
>>  [<a0000001004b0c10>] pci_bus_read_dev_vendor_id+0x50/0x200
>>                                 sp=e000000f3dfcfdd0 bsp=e000000f3dfc1530
>>  [<a0000001008d3d10>] pci_scan_single_device+0x90/0x200
>>                                 sp=e000000f3dfcfdd0 bsp=e000000f3dfc14f8
>>  [<a0000001004b24b0>] pci_scan_slot+0xb0/0x320
>>                                 sp=e000000f3dfcfde0 bsp=e000000f3dfc14a8
>>  [<a0000001008d9e90>] pci_scan_child_bus+0x90/0x2e0
>>                                 sp=e000000f3dfcfde0 bsp=e000000f3dfc1468
>>  [<a0000001008d9580>] pci_scan_bridge+0x540/0xdc0
>>                                 sp=e000000f3dfcfde0 bsp=e000000f3dfc13d0
>>  [<a0000001008da0b0>] pci_scan_child_bus+0x2b0/0x2e0
>>                                 sp=e000000f3dfcfe00 bsp=e000000f3dfc1390
>>  [<a0000001008d5bd0>] pci_rescan_bus+0x50/0x220
>>                                 sp=e000000f3dfcfe00 bsp=e000000f3dfc1358
>>  [<a0000001004c2ab0>] bus_rescan_store+0xf0/0x160
>>                                 sp=e000000f3dfcfe10 bsp=e000000f3dfc1328
>>  [<a0000001006110b0>] bus_attr_store+0x70/0xa0
>>                                 sp=e000000f3dfcfe20 bsp=e000000f3dfc12f0
>>  [<a000000100343b00>] sysfs_write_file+0x240/0x340
>>                                 sp=e000000f3dfcfe20 bsp=e000000f3dfc1298
>>  [<a00000010025e230>] vfs_write+0x1b0/0x3a0
>>                                 sp=e000000f3dfcfe20 bsp=e000000f3dfc1250
>>  [<a00000010025e5e0>] sys_write+0x80/0x100
>>                                 sp=e000000f3dfcfe20 bsp=e000000f3dfc11d0
>>  [<a00000010000bf20>] ia64_ret_from_syscall+0x0/0x20
>>                                 sp=e000000f3dfcfe30 bsp=e000000f3dfc11d0
>>  [<a000000000040720>] __kernel_syscall_via_break+0x0/0x20
>>                                 sp=e000000f3dfd0000 bsp=e000000f3dfc11d0
>> Disabling lock debugging due to kernel taint
>>
>> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
>> Signed-off-by: Jiang Liu <liuj97@xxxxxxxxx>
>> ---
>>  drivers/pci/pcie/aer/aer_inject.c |   21 +++++++++++++++++++++
>>  1 files changed, 21 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/aer/aer_inject.c b/drivers/pci/pcie/aer/aer_inject.c
>> index 5222986..fc28785 100644
>> --- a/drivers/pci/pcie/aer/aer_inject.c
>> +++ b/drivers/pci/pcie/aer/aer_inject.c
>> @@ -109,6 +109,19 @@ static struct aer_error *__find_aer_error_by_dev(struct pci_dev *dev)
>>  	return __find_aer_error((u16)domain, dev->bus->number, dev->devfn);
>>  }
>>
>> +static bool pci_is_upstream_bus(struct pci_bus *bus, struct pci_bus *up_bus)
>> +{
>> +	struct pci_bus *pbus = bus->parent;
>> +
>> +	while (pbus) {
>> +		if (pbus == up_bus)
>> +			return true;
>> +		pbus = pbus->parent;
>> +	}
>> +
>> +	return false;
>> +}
>> +
>>  /* inject_lock must be held before calling */
>>  static struct pci_ops *__find_pci_bus_ops(struct pci_bus *bus)
>>  {
>> @@ -118,6 +131,13 @@ static struct pci_ops *__find_pci_bus_ops(struct pci_bus *bus)
>>  		if (bus_ops->bus == bus)
>>  			return bus_ops->ops;
>>  	}
>> +
>> +	/* here can't find bus_ops, fall back to get bus_ops of upstream bus */
>> +	list_for_each_entry(bus_ops, &pci_bus_ops_list, list) {
>> +		if (pci_is_upstream_bus(bus, bus_ops->bus))
>> +			return bus_ops->ops;
>> +	}
>> +
>>  	return NULL;
>>  }
>>
>> @@ -506,6 +526,7 @@ static struct miscdevice aer_inject_device = {
>>  	.fops = &aer_inject_fops,
>>  };
>>
>> +
>>  static int __init aer_inject_init(void)
>>  {
>>  	return misc_register(&aer_inject_device);
> 
> After
> 
> # rmmod aer_inject
> 
> What will happen?
> 
> Best Regards,
> Huang Ying
> 
> 

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