Messages in this thread | | | Date | Mon, 30 Jan 2012 11:35:29 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [PATCH 1/3] percpu: use ZERO_SIZE_PTR / ZERO_OR_NULL_PTR |
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On Mon, 30 Jan 2012, Tejun Heo wrote:
> I'm pretty sure it never gives out NULL for a dynamic allocation. The > base might be mapped to zero but we're guaranteed to have some static > percpu areas there and IIRC the percpu addresses aren't supposed to > wrap.
True but there is a check for a NULL pointer on free. So a NULL pointer currently has the semantics of being an unallocated per cpu structure. If the allocator returns NULL by accident then we cannot free the per cpu allocation anymore.
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