[PATCH] ARM64: dma-mapping: preallocate DMA-debug hash tables in core_initcall

[catalin.marinas@arm.com (Catalin Marinas)]

On Wed, Nov 16, 2016 at 10:20:13AM +0100, Marek Szyprowski wrote:
> fs_initcall is definitely too late to initialize DMA-debug hash tables,
> because some drivers might get probed and use DMA mapping framework
> already in core_initcall. Late initialization of DMA-debug results in
> false warning about accessing memory, that was not allocated. This issue
> has been observed on ARM 32bit, but the same driver can be used also on
> ARM64.
> 
> This patch moves initialization of DMA-debug to core_initcall. This is
> safe from the initialization perspective. dma_debug_do_init() internally
> calls debugfs functions and debugfs also gets initialised at
> core_initcall(), and that is earlier than arch code in the link order,
> so it will get initialized just before the DMA-debug.

Do we really want to rely on the link order within an initcall level?
What guarantees this?

I hope someone sorts out the deferred probe or some other dependency
detection mechanism to address this issue. But in the meantime I
wouldn't merge a patch which relies on just the link order.

-- 
Catalin