The IOMMU SVA API currently requires device drivers to implement an mm_exit() callback, which stops device jobs that do DMA. This function is called in the release() MMU notifier, when an address space that is shared with a device exits. It has been noted several time during discussions about SVA that cancelling DMA jobs can be slow and complex, and doing it in the release() notifier might cause synchronization issues. Device drivers must in any case call unbind() to remove their bond, after stopping DMA from a more favorable context (release of a file descriptor). Patch 1 removes the mm_exit() callback from the uacce module, and patch 2 removes it from the IOMMU API. Since v1 [1] I fixed the uacce unbind reported by Zhangfei and added details in the commit message of patch 2. Jean-Philippe Brucker (2): uacce: Remove mm_exit() op iommu: Remove iommu_sva_ops::mm_exit() include/linux/iommu.h | 30 ------- include/linux/uacce.h | 34 ++------ drivers/iommu/iommu.c | 11 --- drivers/misc/uacce/uacce.c | 172 +++++++++---------------------------- 4 files changed, 51 insertions(+), 196 deletions(-) -- 2.26.0
