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    Subject[PATCH v7 00/21] Move all drivers to a common dma-buf locking convention
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    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:

    v7: - Rebased on top of recent drm-misc-next.

    - Added ack from Jason Gunthorpe to the RDMA patch.

    - Added iosys_map_clear() to dma_buf_vmap_unlocked(), making it fully
    consistent with dma_buf_vmap().

    v6: - Added r-b from Michael Ruhl to the i915 patch.

    - Added acks from Sumit Semwal and updated commit message of the
    "Move dma_buf_vmap() to dynamic locking specification" patch like
    was suggested by Sumit.

    - Added "!dmabuf" check to dma_buf_vmap_unlocked() to match the locked
    variant of the function, for consistency.

    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 | 216 +++++++++++++++---
    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 | 14 ++
    .../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, 325 insertions(+), 155 deletions(-)

    --
    2.37.3

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