[PATCH v4] cxl: Force context lock during EEH flow

Matthew R. Ochs mrochs at linux.vnet.ibm.com
Fri Apr 14 08:24:18 AEST 2017


> On Apr 11, 2017, at 6:13 AM, Frederic Barrat <fbarrat at linux.vnet.ibm.com> wrote:
> Le 11/04/2017 à 12:40, Michael Ellerman a écrit :
>> Frederic Barrat <fbarrat at linux.vnet.ibm.com> writes:
>> 
>>> Le 05/04/2017 à 13:35, Vaibhav Jain a écrit :
>>>> During an eeh event when the cxl card is fenced and card sysfs attr
>>>> perst_reloads_same_image is set following warning message is seen in the
>>>> kernel logs:
>>>> 
>>>> [   60.622727] Adapter context unlocked with 0 active contexts
>>>> [   60.622762] ------------[ cut here ]------------
>>>> [   60.622771] WARNING: CPU: 12 PID: 627 at
>>>> ../drivers/misc/cxl/main.c:325 cxl_adapter_context_unlock+0x60/0x80 [cxl]
>>>> 
>>>> Even though this warning is harmless, it clutters the kernel log
>>>> during an eeh event. This warning is triggered as the EEH callback
>>>> cxl_pci_error_detected doesn't obtain a context-lock before forcibly
>>>> detaching all active context and when context-lock is released during
>>>> call to cxl_configure_adapter from cxl_pci_slot_reset, a warning in
>>>> cxl_adapter_context_unlock is triggered.
>>>> 
>>>> To fix this warning, we acquire the adapter context-lock via
>>>> cxl_adapter_context_lock() in the eeh callback
>>>> cxl_pci_error_detected() once all the virtual AFU PHBs are notified
>>>> and their contexts detached. The context-lock is released in
>>>> cxl_pci_slot_reset() after the adapter is successfully reconfigured
>>>> and before we call slot_reset callback on slice attached device-drivers.
>>>> 
>>>> Cc: stable at vger.kernel.org
>>>> Fixes: 70b565bbdb91("cxl: Prevent adapter reset if an active context exists")
>>>> Reported-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>
>>>> Signed-off-by: Vaibhav Jain <vaibhav at linux.vnet.ibm.com>
>>>> ---
>>> 
>>> Pending test result from cxl-flash:
>>> Acked-by: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
>> 
>> Still pending ... ?
> 
> Yes, still waiting. It was mentioned in a call with the cxlflash team yesterday.

I have it queued up for us to do on Monday.

-matt



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