Re: [BK-2.5] Update the generic DMA API to take GFP_ flags on

David S. Miller (davem@redhat.com)
Tue, 14 Jan 2003 07:30:23 -0800 (PST)


From: James Bottomley <James.Bottomley@steeleye.com>
Date: Tue, 14 Jan 2003 10:30:15 -0500

A GFP_KERNEL request is safely implemented as GFP_ATOMIC as long as the caller
checks return for NULL. for dma_alloc_coherent return checking is a
requirement because the system may return NULL anyway if it is out of mappings
even with a GFP_KERNEL flag.

Now what about the corollary, a platform that needs
to sleep to setup the cpu mapings in a race-free manner?

It could not ever honor GFP_ATOMIC in that case.
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