Re: [PATCH v5 00/21] Move all drivers to a common dma-buf locking convention
Hi Dmitry, On Wed, 14 Sept 2022 at 00:58, Dmitry Osipenko wrote: > > Hello, > > This series moves all drivers to a dynamic dma-buf locking specification. > From now on all dma-buf importers are made responsible for holding > dma-buf's reservation lock around all operations performed over dma-bufs > in accordance to the locking specification. This allows us to utilize > reservation lock more broadly around kernel without fearing of a potential > deadlocks. Thank you for the excellent work on this series - apart from a minor nit in patch 15, please feel free to add my: Acked-by: Sumit Semwal for the relevant dma-buf patches (1, 2, 15-19, 21). Best regards, Sumit. > > This patchset passes all i915 selftests. It was also tested using VirtIO, > Panfrost, Lima, Tegra, udmabuf, AMDGPU and Nouveau drivers. I tested cases > of display+GPU, display+V4L and GPU+V4L dma-buf sharing (where appropriate), > which covers majority of kernel drivers since rest of the drivers share > same or similar code paths. > > Changelog: > > v5: - Added acks and r-bs that were given to v4. > > - Changed i915 preparation patch like was suggested by Michael Ruhl. > The scope of reservation locking is smaller now. > > v4: - Added dma_buf_mmap() to the "locking convention" documentation, > which was missed by accident in v3. > > - Added acks from Christian König, Tomasz Figa and Hans Verkuil that > they gave to couple v3 patches. > > - Dropped the "_unlocked" postfix from function names that don't have > the locked variant, as was requested by Christian König. > > - Factored out the per-driver preparations into separate patches > to ease reviewing of the changes, which is now doable without the > global dma-buf functions renaming. > > - Factored out the dynamic locking convention enforcements into separate > patches which add the final dma_resv_assert_held(dmabuf->resv) to the > dma-buf API functions. > > v3: - Factored out dma_buf_mmap_unlocked() and attachment functions > into aseparate patches, like was suggested by Christian König. > > - Corrected and factored out dma-buf locking documentation into > a separate patch, like was suggested by Christian König. > > - Intel driver dropped the reservation locking fews days ago from > its BO-release code path, but we need that locking for the imported > GEMs because in the end that code path unmaps the imported GEM. > So I added back the locking needed by the imported GEMs, updating > the "dma-buf attachment locking specification" patch appropriately. > > - Tested Nouveau+Intel dma-buf import/export combo. > > - Tested udmabuf import to i915/Nouveau/AMDGPU. > > - Fixed few places in Etnaviv, Panfrost and Lima drivers that I missed > to switch to locked dma-buf vmapping in the drm/gem: Take reservation > lock for vmap/vunmap operations" patch. In a result invalidated the > Christian's r-b that he gave to v2. > > - Added locked dma-buf vmap/vunmap functions that are needed for fixing > vmappping of Etnaviv, Panfrost and Lima drivers mentioned above. > I actually had this change stashed for the drm-shmem shrinker patchset, > but then realized that it's already needed by the dma-buf patches. > Also improved my tests to better cover these code paths. > > v2: - Changed locking specification to avoid problems with a cross-driver > ww locking, like was suggested by Christian König. Now the attach/detach > callbacks are invoked without the held lock and exporter should take the > lock. > > - Added "locking convention" documentation that explains which dma-buf > functions and callbacks are locked/unlocked for importers and exporters, > which was requested by Christian König. > > - Added ack from Tomasz Figa to the V4L patches that he gave to v1. > > Dmitry Osipenko (21): > dma-buf: Add unlocked variant of vmapping functions > dma-buf: Add unlocked variant of attachment-mapping functions > drm/gem: Take reservation lock for vmap/vunmap operations > drm/prime: Prepare to dynamic dma-buf locking specification > drm/armada: Prepare to dynamic dma-buf locking specification > drm/i915: Prepare to dynamic dma-buf locking specification > drm/omapdrm: Prepare to dynamic dma-buf locking specification > drm/tegra: Prepare to dynamic dma-buf locking specification > drm/etnaviv: Prepare to dynamic dma-buf locking specification > RDMA/umem: Prepare to dynamic dma-buf locking specification > misc: fastrpc: Prepare to dynamic dma-buf locking specification > xen/gntdev: Prepare to dynamic dma-buf locking specification > media: videobuf2: Prepare to dynamic dma-buf locking specification > media: tegra-vde: Prepare to dynamic dma-buf locking specification > dma-buf: Move dma_buf_vmap() to dynamic locking specification > dma-buf: Move dma_buf_attach() to dynamic locking
[PATCH v5 00/21] Move all drivers to a common dma-buf locking convention
Hello, This series moves all drivers to a dynamic dma-buf locking specification. >From now on all dma-buf importers are made responsible for holding dma-buf's reservation lock around all operations performed over dma-bufs in accordance to the locking specification. This allows us to utilize reservation lock more broadly around kernel without fearing of a potential deadlocks. This patchset passes all i915 selftests. It was also tested using VirtIO, Panfrost, Lima, Tegra, udmabuf, AMDGPU and Nouveau drivers. I tested cases of display+GPU, display+V4L and GPU+V4L dma-buf sharing (where appropriate), which covers majority of kernel drivers since rest of the drivers share same or similar code paths. Changelog: v5: - Added acks and r-bs that were given to v4. - Changed i915 preparation patch like was suggested by Michael Ruhl. The scope of reservation locking is smaller now. v4: - Added dma_buf_mmap() to the "locking convention" documentation, which was missed by accident in v3. - Added acks from Christian König, Tomasz Figa and Hans Verkuil that they gave to couple v3 patches. - Dropped the "_unlocked" postfix from function names that don't have the locked variant, as was requested by Christian König. - Factored out the per-driver preparations into separate patches to ease reviewing of the changes, which is now doable without the global dma-buf functions renaming. - Factored out the dynamic locking convention enforcements into separate patches which add the final dma_resv_assert_held(dmabuf->resv) to the dma-buf API functions. v3: - Factored out dma_buf_mmap_unlocked() and attachment functions into aseparate patches, like was suggested by Christian König. - Corrected and factored out dma-buf locking documentation into a separate patch, like was suggested by Christian König. - Intel driver dropped the reservation locking fews days ago from its BO-release code path, but we need that locking for the imported GEMs because in the end that code path unmaps the imported GEM. So I added back the locking needed by the imported GEMs, updating the "dma-buf attachment locking specification" patch appropriately. - Tested Nouveau+Intel dma-buf import/export combo. - Tested udmabuf import to i915/Nouveau/AMDGPU. - Fixed few places in Etnaviv, Panfrost and Lima drivers that I missed to switch to locked dma-buf vmapping in the drm/gem: Take reservation lock for vmap/vunmap operations" patch. In a result invalidated the Christian's r-b that he gave to v2. - Added locked dma-buf vmap/vunmap functions that are needed for fixing vmappping of Etnaviv, Panfrost and Lima drivers mentioned above. I actually had this change stashed for the drm-shmem shrinker patchset, but then realized that it's already needed by the dma-buf patches. Also improved my tests to better cover these code paths. v2: - Changed locking specification to avoid problems with a cross-driver ww locking, like was suggested by Christian König. Now the attach/detach callbacks are invoked without the held lock and exporter should take the lock. - Added "locking convention" documentation that explains which dma-buf functions and callbacks are locked/unlocked for importers and exporters, which was requested by Christian König. - Added ack from Tomasz Figa to the V4L patches that he gave to v1. Dmitry Osipenko (21): dma-buf: Add unlocked variant of vmapping functions dma-buf: Add unlocked variant of attachment-mapping functions drm/gem: Take reservation lock for vmap/vunmap operations drm/prime: Prepare to dynamic dma-buf locking specification drm/armada: Prepare to dynamic dma-buf locking specification drm/i915: Prepare to dynamic dma-buf locking specification drm/omapdrm: Prepare to dynamic dma-buf locking specification drm/tegra: Prepare to dynamic dma-buf locking specification drm/etnaviv: Prepare to dynamic dma-buf locking specification RDMA/umem: Prepare to dynamic dma-buf locking specification misc: fastrpc: Prepare to dynamic dma-buf locking specification xen/gntdev: Prepare to dynamic dma-buf locking specification media: videobuf2: Prepare to dynamic dma-buf locking specification media: tegra-vde: Prepare to dynamic dma-buf locking specification dma-buf: Move dma_buf_vmap() to dynamic locking specification dma-buf: Move dma_buf_attach() to dynamic locking specification dma-buf: Move dma_buf_map_attachment() to dynamic locking specification dma-buf: Move dma_buf_mmap() to dynamic locking specification dma-buf: Document dynamic locking convention media: videobuf2: Stop using internal dma-buf lock dma-buf: Remove obsoleted internal lock Documentation/driver-api/dma-buf.rst | 6 + drivers/dma-buf/dma-buf.c | 211 +++---
