[PATCH 4/4] powerpc/xive: prepare all hcalls to support long busy delays

[Cédric Le Goater]

On 05/07/2018 04:30 AM, Michael Ellerman wrote:
> Benjamin Herrenschmidt <benh at kernel.crashing.org> writes:
>> On Fri, 2018-05-04 at 20:42 +1000, Michael Ellerman wrote:
>>> Cédric Le Goater <clg at kaod.org> writes:
>>>
>>>> This is not the case for the moment, but future releases of pHyp might
>>>> need to introduce some synchronisation routines under the hood which
>>>> would make the XIVE hcalls longer to complete.
>>>>
>>>> As this was done for H_INT_RESET, let's wrap the other hcalls in a
>>>> loop catching the H_LONG_BUSY_* codes.
>>>
>>> Are we sure it's safe to msleep() in all these paths?
>>
>> Probably not. We can have the IRQ descriptor lock. We might need to
>> mdelay.
>>
>> There's a Kconfig option (forgot which one) that will add checks for
>> attempts to sleep inside locks, you should run with that.
> 
> CONFIG_DEBUG_ATOMIC_SLEEP

[  435.757986] kexec_core: Starting new kernel
[  435.778162] BUG: scheduling while atomic: kexec/1633/0x00000003

That proved to be useful. Thanks.

I will resend the full series changing msleep() to mdelay() and fixing
a bit the changelog.

Cheers,

C.