Re: [PATCH 9/9] x86/iommu: use dma_ops_list in get_dma_ops

[Muli Ben-Yehuda <muli@il.ibm.com>]

On Sun, Sep 28, 2008 at 08:44:24PM +0200, Joerg Roedel wrote:

> Hmm, we should only call find_dma_ops_for_device() the first time a
> dma api call is done (look into get_dma_ops). But I also thought
> about how this lock can be avoided. In the real world it should not
> be necessary because the dma_ops list is initialized before dma api
> calls are done. But since there is now a register function which can
> be called its safer this way. What do you think, are we still safe
> enough without this lock?

We could be, if we add a check to the register function that verifies
it isn't being called after DMAs have started. Something like:

in register:

  if (dma_started)
    yell loudly

before PCI device initialization and after IOMMU initialization:
  dma_started = true

Cheers,
Muli
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