On Wed, Jan 18, 2017 at 04:49:58PM +1100, Michael Ellerman wrote:
>Gavin Shan <gws...@linux.vnet.ibm.com> writes:
>
>> In __eeh_clear_pe_frozen_state(), we should pass the flag's value
>> instead of its address to eeh_unfreeze_pe(). This doesn't introduce
>> any problems, but the code is just wrong.
>
>It means any caller that passes false, will be getting the wrong
>behaviour. eg. I see at least one call in eeh_reset_device() which
>passes false to eeh_clear_pe_frozen_state(), which is then passed to
>__eeh_clear_pe_frozen_state().
>
Yes, when __eeh_clear_pe_frozen_state() succeeds on all child PEs, the
isolated flag is cleared. No failure from __eeh_clear_pe_frozen_state()
was observed previously.
>But I guess you're saying that caller doesn't actually see a bug because
>of this?
>
Yes, I'll update the changelog accordingly, to give more details as above.
>> This fixes the code by passing flag's value to eeh_unfreeze_pe().
>>
>> Cc: sta...@vger.kernel.org #3.18+
>> Fixes: 5cfb20b96f6 ("powerpc/eeh: Emulate EEH recovery for VFIO devices")
>> Signed-off-by: Gavin Shan <gws...@linux.vnet.ibm.com>
>>
>> diff --git a/arch/powerpc/kernel/eeh_driver.c
>> b/arch/powerpc/kernel/eeh_driver.c
>> index d88573b..fa15fa6 100644
>> --- a/arch/powerpc/kernel/eeh_driver.c
>> +++ b/arch/powerpc/kernel/eeh_driver.c
>> @@ -549,7 +549,7 @@ static void *__eeh_clear_pe_frozen_state(void *data,
>> void *flag)
>
> bool *clear_sw_state = flag;
>
>> int i, rc = 1;
>>
>> for (i = 0; rc && i < 3; i++)
>> - rc = eeh_unfreeze_pe(pe, clear_sw_state);
>> + rc = eeh_unfreeze_pe(pe, *clear_sw_state);
>
>
>I think it would be better to just do the dereference once:
>
> bool clear_sw_state = *(bool *)flag;
> int i, rc = 1;
>
> for (i = 0; rc && i < 3; i++)
> rc = eeh_unfreeze_pe(pe, clear_sw_state);
>
Thanks, Michael. I'll update in v2.
Thanks,
Gavin
