Re: IB on s390 broken with commit 99db94940 "IB/core: Remove ib_device.dma_device"

From	Sebastian Ott <sebott@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: IB on s390 broken with commit 99db94940 "IB/core: Remove ib_device.dma_device"
Date	2017-02-28 12:00 +0100
Message-ID	<tfNFI-3hi-5@gated-at.bofh.it> (permalink)
References	<tfFI5-6em-1@gated-at.bofh.it> <tfMJz-2En-9@gated-at.bofh.it> <tfMJz-2En-7@gated-at.bofh.it>
Organization	"IBM Deutschland Research & Development GmbH / Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294"

Show all headers | View raw

On Tue, 28 Feb 2017, Sebastian Ott wrote:
> On Mon, 27 Feb 2017, Bart Van Assche wrote:
> > On Mon, 2017-02-27 at 21:17 +0100, Sebastian Ott wrote:
> > > commit 99db94940 "IB/core: Remove ib_device.dma_device"
> > > breaks infiniband on s390 (and I think also other archs that do something
> > > like to_pci_dev(dev) in one of their dma_ops callbacks).
> > > 
> > > With this commit you use the dma_ops of the device that called
> > > ib_register_device but you call e.g. dma_map with ib_device->dev
> > > as an argument.
> > > 
> > > S390's (pci specific) dma_map uses to_pci_dev(dev) to look into the
> > > pci device (and its arch specific data) and oopses.
> > > 
> > > Calling dma_map with ib_device->dev.parent would work but then it
> > > wouldn't make sense to copy dma_ops and mask from ib_device->dev.parent
> > > to ib_device->dev..
> > 
> > How about something like the untested patch below?
> 
> It works but it doesn't feel right (why should all pci devices have this
> duplicated data).
> 
> Frankly I don't get the usecase of infiniband (sometimes) using
> device->dev.dma_ops instead of parent->dma_ops.

Ok, some drivers in drivers/infiniband/sw/ set dma_ops to &dma_virt_ops .

So instead of copying the dma_ops you could do

if (!device->dev.dma_ops) /*or use some new flag for ib_register_device*/
	device->dma_device = parent;
else
	device->dma_device = &device->dev;

Sebastian

Thread

IB on s390 broken with commit 99db94940 "IB/core: Remove  ib_device.dma_device" Sebastian Ott <sebott@linux.vnet.ibm.com> - 2017-02-28 03:30 +0100
  Re: IB on s390 broken with commit 99db94940 "IB/core: Remove  ib_device.dma_device" Sebastian Ott <sebott@linux.vnet.ibm.com> - 2017-02-28 11:00 +0100
    Re: IB on s390 broken with commit 99db94940 "IB/core: Remove  ib_device.dma_device" Sebastian Ott <sebott@linux.vnet.ibm.com> - 2017-02-28 12:00 +0100
    RE: IB on s390 broken with commit 99db94940 "IB/core: Remove  ib_device.dma_device" Parav Pandit <parav@mellanox.com> - 2017-02-28 22:40 +0100

csiph-web