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SubjectRe: [v2 PATCH 1/3] panic: Change nmi_panic from macro to function
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On 03/02/2016 05:18 AM, Michal Hocko wrote:
> On Wed 02-03-16 19:36:26, Hidehiro Kawai wrote:
> [...]
>> +void nmi_panic(struct pt_regs *regs, const char *fmt, ...)
>
> Do we really need vargs? All the current users seem to be OK with a
> simple string. This makes the code slightly more complicated without any
> apparent reason.
>
>> +{
>> + static char buf[1024]; /* protected by panic_cpu */

I am also not too happy with this additional stack allocation.
panic() itself takes varargs. Can those be passed on ?
I understand this would need something like vpanic(), so
maybe that isn't feasible.

Dropping the format, at least for now, might be a simpler option.

Guenter

>> + va_list args;
>> + int old_cpu, cpu;
>> +
>> + cpu = raw_smp_processor_id();
>> + old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
>> +
>> + if (old_cpu == PANIC_CPU_INVALID) {
>> + va_start(args, fmt);
>> + vsnprintf(buf, sizeof(buf), fmt, args);
>> + va_end(args);
>> +
>> + panic("%s", buf);
>> + } else if (old_cpu != cpu)
>> + nmi_panic_self_stop(regs);
>> +}
>> +EXPORT_SYMBOL(nmi_panic);
>> +
>> /**
>> * panic - halt the system
>> * @fmt: The text string to print
>>
>>
>

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