Re: [patch 02/41] cpu alloc: The allocator

Eric Dumazet
2008-06-10T18:05:44Z

Christoph Lameter a écrit :
> On Wed, 4 Jun 2008, Mike Travis wrote:
>
>> I'm a bit confused. Why is DEFINE_PER_CPU_SHARED_ALIGNED() conditioned on
>> ifdef MODULE?
>>
>> #ifdef MODULE
>> #define SHARED_ALIGNED_SECTION ".data.percpu"
>> #else
>> #define SHARED_ALIGNED_SECTION ".data.percpu.shared_aligned"
>> #endif
>>
>> #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
>> __attribute__((__section__(SHARED_ALIGNED_SECTION))) \
>> PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name \
>> ____cacheline_aligned_in_smp
>
> Looks wrong to me. There can be shared objects even without modules.
>
>

Well, MODULE is not CONFIG_MODULES :)

If compiling an object that is going to be statically linked to kernel,
MODULE is not defined, so we have shared objects.

When compiling a module, we cannot *yet* use .data.percpu.shared_aligned
section, since module loader wont handle this section.

Alternative is to change modules linking for all arches to merge
.data.percpu{*} subsections correctly, or tell module loader to take
into account all .data.percpu sections.

AFAIK no module uses DEFINE_PER_CPU_SHARED_ALIGNED() yet...