On 08/03/2018 12:22 PM, Matthew Wilcox wrote: > On Fri, Aug 03, 2018 at 06:59:20PM +0300, Andy Shevchenko wrote: >>>>> I'm pretty sure this was created in an order to avoid bad looking (and >>>>> in some cases frightening) "NULL device *" part. >> JFYI: git log --no-merges --grep 'NULL device \*' > I think those commits actually argue in favour of Tony's patch to remove > the special casing. Is it really useful to create dma pools with a NULL > device? > > dma_alloc_coherent() does appear to support a NULL dev, so it might make sense in theory. But I can't find any in-tree callers that actually pass a NULL dev to dma_pool_create(). So for one of the dreaded (NULL device *) messages to show up, it would take both a new caller that passes a NULL dev to dma_pool_create() and a bug to cause the message to be printed. Is that worth the special casing?