Michael Ellerman <m...@ellerman.id.au> writes:
> Christophe Leroy <christophe.le...@csgroup.eu> writes:
>> Le 11/02/2023 à 00:56, Nathan Lynch via B4 Submission Endpoint a écrit :
>>> From: Nathan Lynch <nath...@linux.ibm.com>
>>>
>>> machine_is() can't provide correct results before probe_machine() has
>>> run. Warn when it's used too early in boot.
>>>
>>> Signed-off-by: Nathan Lynch <nath...@linux.ibm.com>
>>> ---
>>> Prompted by my attempts to do some pseries-specific setup during
>>> rtas_initialize() and being puzzled for a while that it wasn't
>>> working.
>>> ---
>>> arch/powerpc/include/asm/machdep.h | 12 +++++++-----
>>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/machdep.h
>>> b/arch/powerpc/include/asm/machdep.h
>>> index 378b8d5836a7..8c0a799d18cd 100644
>>> --- a/arch/powerpc/include/asm/machdep.h
>>> +++ b/arch/powerpc/include/asm/machdep.h
>>> @@ -220,11 +220,13 @@ extern struct machdep_calls *machine_id;
>>> EXPORT_SYMBOL(mach_##name); \
>>> struct machdep_calls mach_##name __machine_desc =
>>>
>>> -#define machine_is(name) \
>>> - ({ \
>>> - extern struct machdep_calls mach_##name \
>>> - __attribute__((weak)); \
>>> - machine_id == &mach_##name; \
>>> +#define machine_is(name) \
>>> + ({ \
>>> + extern struct machdep_calls mach_##name \
>>> + __attribute__((weak)); \
>>> + WARN(!machine_id, \
>>> + "machine_is() called before probe_machine()"); \
>>
>> Is a WARN() really necessary ? WARN() is less optimised than WARN_ON(),
>> especially on PPC64.
>>
>> This should never ever happen so a WARN_ON(!machine_id) should be
>> enough, the developper that hits it is able to go to the given file:line
>> and understand what happened.
>
> Yeah I agree, WARN_ON() should be sufficient here, and should generate
> slightly better code. We have > 100 uses of machine_is(), so keeping
> each small is desirable.
Sure, I'll change it.
