On Thu, Jan 24, 2019 at 09:24:31AM +0100, Joerg Roedel wrote:

On Wed, Jan 23, 2019 at 10:28:13PM +0100, Christoph Hellwig wrote:

quoted

On Wed, Jan 23, 2019 at 05:30:45PM +0100, Joerg Roedel wrote:

quoted

+extern size_t swiotlb_max_mapping_size(struct device *dev);

No need for the extern keyword on function declarations in headers.

Right, but all other function declarations in that header file have
'extern' too, so I added it also for that one.

Your patch 3 also doesn't use an extern.  And I have to say I
much prefer it that way..