Hi Alan, > From: Alan Stern, Sent: Tuesday, July 2, 2019 11:28 PM > > On Tue, 2 Jul 2019, Yoshihiro Shimoda wrote: > > > Hi Alan, shuah, Suwan, > > > > > From: Christoph Hellwig, Sent: Monday, June 17, 2019 3:22 PM > > > > > > On Mon, Jun 17, 2019 at 04:17:43AM +0000, Yoshihiro Shimoda wrote: > > > > Thank you for the comments. So, should I wait for getting rid of the > > > > virt_boundary_mask stuff? If I revise the commit log of this patch, > > > > is it acceptable for v5.2-stable as a workaround? In other words, > > > > I worry about this issue exists on v5.2-stable. > > > > > > It does exist on 5.2-stable and we should fix it. I'll plan to resend > > > my series to fix the virt_boundary issues for the other SCSI driver > > > soon, but we'll still need to sort out usb-storage. > > > > I guess that getting rid of the virt_boundary_mask stuff [1] needs more time. > > So, for v5.2-stable, would you accept my patch as a workaround? > > JFYI, v5.2-rc7 still has this "swiotlb buffer is full" issue. > > > > [1] > > https://marc.info/?l=linux-kernel&m=156114524808042&w=2 > > I would really prefer to see a different solution. > > The actual problem is that the usb_device and usb_interface structures > are supposed to inherit all of their DMA properties from the bus's host > controller. But the existing code copies only the dma_mask and > dma_pfn_offset fields in the embedded device structures. If we copied > all of the important DMA fields then this patch wouldn't be needed; the > max_sectors value for the request queue would be set up correctly to > begin with. I'm sorry, but I cannot understand what are important DMA fields. IIUC, usb-storage driver should take care of calling blk_queue_ APIs anyway because: - As Christoph mentioned before on the email [1], usb-storage has a special max_sectors quirk for tape and SuperSpeed devices. - Since blk_queue_* APIs don't take device structure pointer, the block layer cannot call any DMA mapping APIs. So, even if any other DMA fields are copied, the behavior is not changed. [1] https://www.spinics.net/lists/linux-usb/msg181527.html What do you think? Best regards, Yoshihiro Shimoda > So what I would like to see is a new subroutine -- perhaps in the > driver core -- that copies the DMA fields from one struct device to > another. Then we could call this subroutine in usb_alloc_dev() and > usb_set_configuration() instead of copying the information manually. > > Greg and Christoph, does that make sense? > > Yoshihiro, would you like to write a patch that does this? > > Alan Stern
