powerpc: eeh: Fix oops when probing in early boot

If we take an EEH early enough, we oops:


Call Trace:
[c000000010483770] [c000000000013ee4] .show_stack+0xd8/0x218 (unreliable)
[c000000010483850] [c000000000658940] .dump_stack+0x28/0x3c
[c0000000104838d0] [c000000000057a68] .eeh_dn_check_failure+0x2b8/0x304
[c000000010483990] [c0000000000259c8] .rtas_read_config+0x120/0x168
[c000000010483a40] [c000000000025af4] .rtas_pci_read_config+0xe4/0x124
[c000000010483af0] [c00000000037af18] .pci_bus_read_config_word+0xac/0x104
[c000000010483bc0] [c0000000008fec98] .pcibios_allocate_resources+0x7c/0x220
[c000000010483c90] [c0000000008feed8] .pcibios_resource_survey+0x9c/0x418
[c000000010483d80] [c0000000008fea10] .pcibios_init+0xbc/0xf4
[c000000010483e20] [c000000000009844] .do_one_initcall+0x98/0x1d8
[c000000010483ed0] [c0000000008f0560] .kernel_init+0x228/0x2e8
[c000000010483f90] [c000000000031a08] .kernel_thread+0x54/0x70
EEH: Detected PCI bus error on device <null>
EEH: This PCI device has failed 1 times in the last hour:
EEH: location=U78A5.001.WIH8464-P1 driver= pci addr=0001:00:01.0
EEH: of node=/pci@800000020000209/usb@1
EEH: PCI device/vendor: 00351033
EEH: PCI cmd/status register: 12100146

Unable to handle kernel paging request for data at address 0x00000468
Oops: Kernel access of bad area, sig: 11 [#1]
....
NIP [c000000000057610] .rtas_set_slot_reset+0x38/0x10c
LR [c000000000058724] .eeh_reset_device+0x5c/0x124
Call Trace:
[c00000000bc6bd00] [c00000000005a0e0] .pcibios_remove_pci_devices+0x7c/0xb0 (unreliable)
[c00000000bc6bd90] [c000000000058724] .eeh_reset_device+0x5c/0x124
[c00000000bc6be40] [c0000000000589c0] .handle_eeh_events+0x1d4/0x39c
[c00000000bc6bf00] [c000000000059124] .eeh_event_handler+0xf0/0x188
[c00000000bc6bf90] [c000000000031a08] .kernel_thread+0x54/0x70


We called rtas_set_slot_reset while scanning the bus and before the pci_dn
to pcidev mapping has been created. Since we only need the pcidev to work
out the type of reset and that only gets set after the module for the
device loads, lets just do a hot reset if the pcidev is NULL.

Signed-off-by: Anton Blanchard <anton@samba.org>
---

On 10 May 2010 20:38, Anton Blanchard <anton@samba.org> wrote:
>
> If we take an EEH early enough, we oops:
>
>
> Call Trace:
> [c000000010483770] [c000000000013ee4] .show_stack+0xd8/0x218 (unreliable)
> [c000000010483850] [c000000000658940] .dump_stack+0x28/0x3c
> [c0000000104838d0] [c000000000057a68] .eeh_dn_check_failure+0x2b8/0x304
> [c000000010483990] [c0000000000259c8] .rtas_read_config+0x120/0x168
> [c000000010483a40] [c000000000025af4] .rtas_pci_read_config+0xe4/0x124
> [c000000010483af0] [c00000000037af18] .pci_bus_read_config_word+0xac/0x104
> [c000000010483bc0] [c0000000008fec98] .pcibios_allocate_resources+0x7c/0x220
> [c000000010483c90] [c0000000008feed8] .pcibios_resource_survey+0x9c/0x418
> [c000000010483d80] [c0000000008fea10] .pcibios_init+0xbc/0xf4
> [c000000010483e20] [c000000000009844] .do_one_initcall+0x98/0x1d8
> [c000000010483ed0] [c0000000008f0560] .kernel_init+0x228/0x2e8
> [c000000010483f90] [c000000000031a08] .kernel_thread+0x54/0x70
> EEH: Detected PCI bus error on device <null>
> EEH: This PCI device has failed 1 times in the last hour:
> EEH: location=U78A5.001.WIH8464-P1 driver= pci addr=0001:00:01.0
> EEH: of node=/pci@800000020000209/usb@1
> EEH: PCI device/vendor: 00351033
> EEH: PCI cmd/status register: 12100146
>
> Unable to handle kernel paging request for data at address 0x00000468
> Oops: Kernel access of bad area, sig: 11 [#1]
> ....
> NIP [c000000000057610] .rtas_set_slot_reset+0x38/0x10c
> LR [c000000000058724] .eeh_reset_device+0x5c/0x124
> Call Trace:
> [c00000000bc6bd00] [c00000000005a0e0] .pcibios_remove_pci_devices+0x7c/0xb0 (unreliable)
> [c00000000bc6bd90] [c000000000058724] .eeh_reset_device+0x5c/0x124
> [c00000000bc6be40] [c0000000000589c0] .handle_eeh_events+0x1d4/0x39c
> [c00000000bc6bf00] [c000000000059124] .eeh_event_handler+0xf0/0x188
> [c00000000bc6bf90] [c000000000031a08] .kernel_thread+0x54/0x70
>
>
> We called rtas_set_slot_reset while scanning the bus and before the pci_dn
> to pcidev mapping has been created. Since we only need the pcidev to work
> out the type of reset and that only gets set after the module for the
> device loads, lets just do a hot reset if the pcidev is NULL.
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---


Acked-by: Linas Vepstas <linasvepstas@gmail.com>

I'm cc'ing Brian King, he's the one who figured out the proper fix
for a hot-reset/fundamental-reset hardware "feature" that added
this line of code.

The question is -- when the system finishes booting, and the
module finally loads, will the device be found in a usable state
and/or will it automatically reset to a usable state?

--linas

>
> Index: linux-2.6/arch/powerpc/platforms/pseries/eeh.c
> ===================================================================
> --- linux-2.6.orig/arch/powerpc/platforms/pseries/eeh.c 2010-05-10 17:25:10.703453565 +1000
> +++ linux-2.6/arch/powerpc/platforms/pseries/eeh.c      2010-05-10 17:25:24.034323030 +1000
> @@ -749,7 +749,7 @@ static void __rtas_set_slot_reset(struct
>        /* Determine type of EEH reset required by device,
>         * default hot reset or fundamental reset
>         */
> -       if (dev->needs_freset)
> +       if (dev && dev->needs_freset)
>                rtas_pci_slot_reset(pdn, 3);
>        else
>                rtas_pci_slot_reset(pdn, 1);
>
>

The needs_freset bit went in since the last time I touched
all this code, so I don't think this will affect ipr at least.
The way this works for the ipr adapters we needed a warm reset
for was, we would get the hot reset in the generic EEH code, the
the ipr driver would come along after that and issue a warm
reset to get the adapter in a usable state. Now that the needs_freset
feature is there, we could set that in ipr for the adapters we need
a warm reset for and get rid of the useless hot reset.

A quick grep through the code shows that qlogic is the one user of this
feature. 

How early is this? I assume this is pre driver load time, in which
case even if we could check the flag it wouldn't be set yet...

Thanks,

Brian


On 05/11/2010 01:59 PM, Linas Vepstas wrote:
> On 10 May 2010 20:38, Anton Blanchard <anton@samba.org> wrote:
>>
>> If we take an EEH early enough, we oops:
>>
>> 
>> Call Trace:
>> [c000000010483770] [c000000000013ee4] .show_stack+0xd8/0x218 (unreliable)
>> [c000000010483850] [c000000000658940] .dump_stack+0x28/0x3c
>> [c0000000104838d0] [c000000000057a68] .eeh_dn_check_failure+0x2b8/0x304
>> [c000000010483990] [c0000000000259c8] .rtas_read_config+0x120/0x168
>> [c000000010483a40] [c000000000025af4] .rtas_pci_read_config+0xe4/0x124
>> [c000000010483af0] [c00000000037af18] .pci_bus_read_config_word+0xac/0x104
>> [c000000010483bc0] [c0000000008fec98] .pcibios_allocate_resources+0x7c/0x220
>> [c000000010483c90] [c0000000008feed8] .pcibios_resource_survey+0x9c/0x418
>> [c000000010483d80] [c0000000008fea10] .pcibios_init+0xbc/0xf4
>> [c000000010483e20] [c000000000009844] .do_one_initcall+0x98/0x1d8
>> [c000000010483ed0] [c0000000008f0560] .kernel_init+0x228/0x2e8
>> [c000000010483f90] [c000000000031a08] .kernel_thread+0x54/0x70
>> EEH: Detected PCI bus error on device <null>
>> EEH: This PCI device has failed 1 times in the last hour:
>> EEH: location=U78A5.001.WIH8464-P1 driver= pci addr=0001:00:01.0
>> EEH: of node=/pci@800000020000209/usb@1
>> EEH: PCI device/vendor: 00351033
>> EEH: PCI cmd/status register: 12100146
>>
>> Unable to handle kernel paging request for data at address 0x00000468
>> Oops: Kernel access of bad area, sig: 11 [#1]
>> ....
>> NIP [c000000000057610] .rtas_set_slot_reset+0x38/0x10c
>> LR [c000000000058724] .eeh_reset_device+0x5c/0x124
>> Call Trace: 
>> [c00000000bc6bd00] [c00000000005a0e0] .pcibios_remove_pci_devices+0x7c/0xb0 (unreliable)
>> [c00000000bc6bd90] [c000000000058724] .eeh_reset_device+0x5c/0x124
>> [c00000000bc6be40] [c0000000000589c0] .handle_eeh_events+0x1d4/0x39c
>> [c00000000bc6bf00] [c000000000059124] .eeh_event_handler+0xf0/0x188
>> [c00000000bc6bf90] [c000000000031a08] .kernel_thread+0x54/0x70
>>
>>
>> We called rtas_set_slot_reset while scanning the bus and before the pci_dn
>> to pcidev mapping has been created. Since we only need the pcidev to work
>> out the type of reset and that only gets set after the module for the
>> device loads, lets just do a hot reset if the pcidev is NULL.
>>
>> Signed-off-by: Anton Blanchard <anton@samba.org>
>> ---
> 
> 
> Acked-by: Linas Vepstas <linasvepstas@gmail.com>
> 
> I'm cc'ing Brian King, he's the one who figured out the proper fix
> for a hot-reset/fundamental-reset hardware "feature" that added
> this line of code.
> 
> The question is -- when the system finishes booting, and the
> module finally loads, will the device be found in a usable state
> and/or will it automatically reset to a usable state?
> 
> --linas
> 
>>
>> Index: linux-2.6/arch/powerpc/platforms/pseries/eeh.c
>> ===================================================================
>> --- linux-2.6.orig/arch/powerpc/platforms/pseries/eeh.c 2010-05-10 17:25:10.703453565 +1000
>> +++ linux-2.6/arch/powerpc/platforms/pseries/eeh.c      2010-05-10 17:25:24.034323030 +1000
>> @@ -749,7 +749,7 @@ static void __rtas_set_slot_reset(struct
>>        /* Determine type of EEH reset required by device,
>>         * default hot reset or fundamental reset
>>         */
>> -       if (dev->needs_freset)
>> +       if (dev && dev->needs_freset)
>>                rtas_pci_slot_reset(pdn, 3);
>>        else
>>                rtas_pci_slot_reset(pdn, 1);
>>
>>