Re: [PATCH v5 02/14] driver core: Add dma_cleanup callback in bus_type

[Greg Kroah-Hartman]

On Tue, Feb 08, 2022 at 01:55:29PM +0800, Lu Baolu wrote:
> Hi Greg,
> 
> On 1/4/22 9:04 PM, Greg Kroah-Hartman wrote:
> > On Tue, Jan 04, 2022 at 08:39:11AM -0400, Jason Gunthorpe wrote:
> > > On Tue, Jan 04, 2022 at 02:08:36AM -0800, Christoph Hellwig wrote:
> > > > All these bus callouts still looks horrible and just create tons of
> > > > boilerplate code.
> > > 
> > > Yes, Lu - Greg asked questions then didn't respond to their answers
> > > meaning he accepts them, you should stick with the v4 version.
> > 
> > Trying to catch up on emails from the break, that was way down my list
> > of things to get back to as it's messy and non-obvious.  I'll revisit it
> > again after 5.17-rc1 is out, this is too late for that merge window
> > anyway.
> 
> In this series we want to add calls into the iommu subsystem during
> device driver binding/unbinding, so that the device DMA ownership
> conflict (kernel driver vs. user-space) could be detected and avoided
> before calling into device driver's .probe().
> 
> In this v5 series, we implemented this in the affected buses (amba/
> platform/fsl-mc/pci) which are known to support assigning devices to
> user space through the vfio framework currently. And more buses are
> possible to be affected in the future if they also want to support
> device assignment. Christoph commented that this will create boilerplate
> code in various bus drivers.
> 
> Back to v4 of this series (please refer to below link [1]), we added
> this call in the driver core if buses have provided the dma_configure()
> callback (please refer to below link [2]).
> 
> Which would you prefer, or any other suggestions? We need your guide to
> move this series ahead. Please help to suggest.
> 
> [1] https://lore.kernel.org/linux-iommu/20211217063708.1740334-1-baolu.lu@xxxxxxxxxxxxxxx/
> [2] https://lore.kernel.org/linux-iommu/20211217063708.1740334-3-baolu.lu@xxxxxxxxxxxxxxx/

Let me look over the series again this afternooon.

thanks,

greg k-h