Hi Dmitry,
I've gone over this multiple times now and while it is still possible that we missed something I think that this should land now.
The whole topic is just to complicated that we can 100% sure guarantee that there isn't anything wrong with the locking, but lockdep and driver testing should allow us to quickly find remaining issues.
Do you have commit rights to drm-misc-next or should I push it?
Thanks, Christian.
Am 31.08.22 um 17:37 schrieb Dmitry Osipenko:
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:
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 +++++++++++++++--- drivers/gpu/drm/armada/armada_gem.c | 8 +- drivers/gpu/drm/drm_client.c | 4 +- drivers/gpu/drm/drm_gem.c | 24 ++ drivers/gpu/drm/drm_gem_dma_helper.c | 6 +- drivers/gpu/drm/drm_gem_framebuffer_helper.c | 6 +- drivers/gpu/drm/drm_gem_ttm_helper.c | 9 +- drivers/gpu/drm/drm_prime.c | 6 +- drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 2 +- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 2 +- drivers/gpu/drm/i915/gem/i915_gem_object.c | 12 + .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 16 +- drivers/gpu/drm/lima/lima_sched.c | 4 +- drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 4 +- drivers/gpu/drm/panfrost/panfrost_dump.c | 4 +- drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 6 +- drivers/gpu/drm/qxl/qxl_object.c | 17 +- drivers/gpu/drm/qxl/qxl_prime.c | 4 +- drivers/gpu/drm/tegra/gem.c | 17 +- drivers/infiniband/core/umem_dmabuf.c | 7 +- .../common/videobuf2/videobuf2-dma-contig.c | 22 +- .../media/common/videobuf2/videobuf2-dma-sg.c | 19 +- .../common/videobuf2/videobuf2-vmalloc.c | 17 +- .../platform/nvidia/tegra-vde/dmabuf-cache.c | 6 +- drivers/misc/fastrpc.c | 6 +- drivers/xen/gntdev-dmabuf.c | 8 +- include/drm/drm_gem.h | 3 + include/linux/dma-buf.h | 17 +- 29 files changed, 318 insertions(+), 155 deletions(-)