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2021-01-18dma-buf: Add debug optionDaniel Vetter
We have too many people abusing the struct page they can get at but really shouldn't in importers. Aside from that the backing page might simply not exist (for dynamic p2p mappings) looking at it and using it e.g. for mmap can also wreak the page handling of the exporter completely. Importers really must go through the proper interface like dma_buf_mmap for everything. I'm semi-tempted to enforce this for dynamic importers since those really have no excuse at all to break the rules. Unfortuantely we can't store the right pointers somewhere safe to make sure we oops on something recognizable, so best is to just wrangle them a bit by flipping all the bits. At least on x86 kernel addresses have all their high bits sets and the struct page array is fairly low in the kernel mapping, so flipping all the bits gives us a very high pointer in userspace and hence excellent chances for an invalid dereference. v2: Add a note to the @map_dma_buf hook that exporters shouldn't do fancy caching tricks, which would blow up with this address scrambling trick here (Chris) Enable by default when CONFIG_DMA_API_DEBUG is enabled. v3: Only one copy of the mangle/unmangle code (Christian) v4: #ifdef, not #if (0day) v5: sg_table can also be an ERR_PTR (Chris, Christian) Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: "Christian König" <christian.koenig@amd.com> Cc: David Stevens <stevensd@chromium.org> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20210115164739.3958206-1-daniel.vetter@ffwll.ch
2020-06-14treewide: replace '---help---' in Kconfig files with 'help'Masahiro Yamada
Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over '---help---'"), the number of '---help---' has been gradually decreasing, but there are still more than 2400 instances. This commit finishes the conversion. While I touched the lines, I also fixed the indentation. There are a variety of indentation styles found. a) 4 spaces + '---help---' b) 7 spaces + '---help---' c) 8 spaces + '---help---' d) 1 space + 1 tab + '---help---' e) 1 tab + '---help---' (correct indentation) f) 1 tab + 1 space + '---help---' g) 1 tab + 2 spaces + '---help---' In order to convert all of them to 1 tab + 'help', I ran the following commend: $ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/' Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-25dma-buf: Improve CONFIG_DMABUF_MOVE_NOTIFY help textGeert Uytterhoeven
Improve the help text for the CONFIG_DMABUF_MOVE_NOTIFY symbol by: 1. Removing duplicated single quotes, 2. Adding a missing subject, 3. Fixing a misspelling of "yet", 4. Wrapping long lines. Fixes: bb42df4662a44765 ("dma-buf: add dynamic DMA-buf handling v15") Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200324125442.21983-1-geert+renesas@glider.be
2020-02-27dma-buf: add dynamic DMA-buf handling v15Christian König
On the exporter side we add optional explicit pinning callbacks. Which are called when the importer doesn't implement dynamic handling, move notification or need the DMA-buf locked in place for its use case. On the importer side we add an optional move_notify callback. This callback is used by the exporter to inform the importers that their mappings should be destroyed as soon as possible. This allows the exporter to provide the mappings without the need to pin the backing store. v2: don't try to invalidate mappings when the callback is NULL, lock the reservation obj while using the attachments, add helper to set the callback v3: move flag for invalidation support into the DMA-buf, use new attach_info structure to set the callback v4: use importer_priv field instead of mangling exporter priv. v5: drop invalidation_supported flag v6: squash together with pin/unpin changes v7: pin/unpin takes an attachment now v8: nuke dma_buf_attachment_(map|unmap)_locked, everything is now handled backward compatible v9: always cache when export/importer don't agree on dynamic handling v10: minimal style cleanup v11: drop automatically re-entry avoidance v12: rename callback to move_notify v13: add might_lock in appropriate places v14: rebase on separated locking change v15: add EXPERIMENTAL flag, some more code comments Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/353993/?series=73646&rev=1
2020-02-17dma-buf: Fix a typo in KconfigChristophe JAILLET
A 'h' ismissing in' syncronization' Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20200216114708.20583-1-christophe.jaillet@wanadoo.fr
2019-12-11dma-buf: heaps: Add system heap to dmabuf heapsJohn Stultz
This patch adds system heap to the dma-buf heaps framework. This allows applications to get a page-allocator backed dma-buf for non-contiguous memory. This code is an evolution of the Android ION implementation, so thanks to its original authors and maintainters: Rebecca Schultz Zavin, Colin Cross, Laura Abbott, and others! Cc: Laura Abbott <labbott@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Pratik Patel <pratikp@codeaurora.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Vincent Donnefort <Vincent.Donnefort@arm.com> Cc: Sudipto Paul <Sudipto.Paul@arm.com> Cc: Andrew F. Davis <afd@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chenbo Feng <fengc@google.com> Cc: Alistair Strachan <astrachan@google.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Sandeep Patil <sspatil@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Dave Airlie <airlied@gmail.com> Cc: dri-devel@lists.freedesktop.org Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Reviewed-by: Brian Starkey <brian.starkey@arm.com> Acked-by: Sandeep Patil <sspatil@android.com> Acked-by: Laura Abbott <labbott@redhat.com> Tested-by: Ayan Kumar Halder <ayan.halder@arm.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20191203172641.66642-4-john.stultz@linaro.org
2019-12-11dma-buf: Add dma-buf heaps frameworkAndrew F. Davis
This framework allows a unified userspace interface for dma-buf exporters, allowing userland to allocate specific types of memory for use in dma-buf sharing. Each heap is given its own device node, which a user can allocate a dma-buf fd from using the DMA_HEAP_IOC_ALLOC. This code is an evoluiton of the Android ION implementation, and a big thanks is due to its authors/maintainers over time for their effort: Rebecca Schultz Zavin, Colin Cross, Benjamin Gaignard, Laura Abbott, and many other contributors! Cc: Laura Abbott <labbott@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Pratik Patel <pratikp@codeaurora.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Vincent Donnefort <Vincent.Donnefort@arm.com> Cc: Sudipto Paul <Sudipto.Paul@arm.com> Cc: Andrew F. Davis <afd@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chenbo Feng <fengc@google.com> Cc: Alistair Strachan <astrachan@google.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Sandeep Patil <sspatil@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Dave Airlie <airlied@gmail.com> Cc: dri-devel@lists.freedesktop.org Reviewed-by: Brian Starkey <brian.starkey@arm.com> Acked-by: Sandeep Patil <sspatil@android.com> Signed-off-by: Andrew F. Davis <afd@ti.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20191203172641.66642-2-john.stultz@linaro.org
2019-10-30Revert "dma-buf: Add dma-buf heaps framework"Sean Paul
This reverts commit a69b0e855d3fd278ff6f09a23e1edf929538e304. This patchset doesn't meet the UAPI requirements set out in [1] for the DRM subsystem. Once the userspace component is reviewed and ready for merge we can try again. [1]- https://01.org/linuxgraphics/gfx-docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements Fixes: a69b0e855d3f ("dma-buf: Add dma-buf heaps framework") Cc: Laura Abbott <labbott@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Pratik Patel <pratikp@codeaurora.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Vincent Donnefort <Vincent.Donnefort@arm.com> Cc: Sudipto Paul <Sudipto.Paul@arm.com> Cc: Andrew F. Davis <afd@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chenbo Feng <fengc@google.com> Cc: Alistair Strachan <astrachan@google.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: dri-devel@lists.freedesktop.org Cc: Brian Starkey <brian.starkey@arm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rob Herring <robh@kernel.org> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: "Paul E. McKenney" <paulmck@linux.ibm.com> Cc: Sean Paul <seanpaul@chromium.org> Cc: "Andrew F. Davis" <afd@ti.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Acked-by: David Airlie <airlied@linux.ie> Signed-off-by: Sean Paul <sean@poorly.run> Link: https://patchwork.freedesktop.org/patch/msgid/20191030203003.101156-6-sean@poorly.run
2019-10-30Revert "dma-buf: heaps: Add system heap to dmabuf heaps"Sean Paul
This reverts commit 47a32f9c12266d450b92089148c6039591bd9909. This patchset doesn't meet the UAPI requirements set out in [1] for the DRM subsystem. Once the userspace component is reviewed and ready for merge we can try again. [1]- https://01.org/linuxgraphics/gfx-docs/drm/gpu/drm-uapi.html#open-source-userspace-requirements Fixes: 47a32f9c1226 ("dma-buf: heaps: Add system heap to dmabuf heaps") Cc: Laura Abbott <labbott@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Pratik Patel <pratikp@codeaurora.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Vincent Donnefort <Vincent.Donnefort@arm.com> Cc: Sudipto Paul <Sudipto.Paul@arm.com> Cc: Andrew F. Davis <afd@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chenbo Feng <fengc@google.com> Cc: Alistair Strachan <astrachan@google.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: dri-devel@lists.freedesktop.org Cc: Brian Starkey <brian.starkey@arm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: "Andrew F. Davis" <afd@ti.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Acked-by: David Airlie <airlied@linux.ie> Signed-off-by: Sean Paul <sean@poorly.run> Link: https://patchwork.freedesktop.org/patch/msgid/20191030203003.101156-4-sean@poorly.run
2019-10-25dma-buf: heaps: Add system heap to dmabuf heapsJohn Stultz
This patch adds system heap to the dma-buf heaps framework. This allows applications to get a page-allocator backed dma-buf for non-contiguous memory. This code is an evolution of the Android ION implementation, so thanks to its original authors and maintainters: Rebecca Schultz Zavin, Colin Cross, Laura Abbott, and others! Cc: Laura Abbott <labbott@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Pratik Patel <pratikp@codeaurora.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Vincent Donnefort <Vincent.Donnefort@arm.com> Cc: Sudipto Paul <Sudipto.Paul@arm.com> Cc: Andrew F. Davis <afd@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chenbo Feng <fengc@google.com> Cc: Alistair Strachan <astrachan@google.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: dri-devel@lists.freedesktop.org Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Reviewed-by: Brian Starkey <brian.starkey@arm.com> Acked-by: Laura Abbott <labbott@redhat.com> Tested-by: Ayan Kumar Halder <ayan.halder@arm.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20191021190310.85221-4-john.stultz@linaro.org
2019-10-25dma-buf: Add dma-buf heaps frameworkAndrew F. Davis
This framework allows a unified userspace interface for dma-buf exporters, allowing userland to allocate specific types of memory for use in dma-buf sharing. Each heap is given its own device node, which a user can allocate a dma-buf fd from using the DMA_HEAP_IOC_ALLOC. This code is an evoluiton of the Android ION implementation, and a big thanks is due to its authors/maintainers over time for their effort: Rebecca Schultz Zavin, Colin Cross, Benjamin Gaignard, Laura Abbott, and many other contributors! Cc: Laura Abbott <labbott@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Liam Mark <lmark@codeaurora.org> Cc: Pratik Patel <pratikp@codeaurora.org> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Vincent Donnefort <Vincent.Donnefort@arm.com> Cc: Sudipto Paul <Sudipto.Paul@arm.com> Cc: Andrew F. Davis <afd@ti.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chenbo Feng <fengc@google.com> Cc: Alistair Strachan <astrachan@google.com> Cc: Hridya Valsaraju <hridya@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: dri-devel@lists.freedesktop.org Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Reviewed-by: Brian Starkey <brian.starkey@arm.com> Acked-by: Laura Abbott <labbott@redhat.com> Tested-by: Ayan Kumar Halder <ayan.halder@arm.com> Signed-off-by: Andrew F. Davis <afd@ti.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20191021190310.85221-2-john.stultz@linaro.org
2019-08-19dma-buf: Introduce selftesting frameworkChris Wilson
In light of recent review slip ups, the absence of a suite of tests for dma-buf became apparent. Given the current plethora of testing frameworks, opt for one already in use by Intel's CI and so allow easy hook up into igt. We introduce a new module that when loaded will execute the list of selftests and their subtest. The names of the selftests are put into the modinfo as parameters so that igt can identify each, and run them independently, principally for ease of error reporting. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Tomi Sarvela <tomi.p.sarvela@intel.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20190819095928.32091-1-chris@chris-wilson.co.uk
2019-07-15docs: driver-api: add a series of orphaned documentsMauro Carvalho Chehab
There are lots of documents under Documentation/*.txt and a few other orphan documents elsehwere that belong to the driver-API book. Move them to their right place. Reviewed-by: Cornelia Huck <cohuck@redhat.com> # vfio-related parts Acked-by: Logan Gunthorpe <logang@deltatee.com> # switchtec Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-05-21treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner
Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-19Make anon_inodes unconditionalDavid Howells
Make the anon_inodes facility unconditional so that it can be used by core VFS code and pidfd code. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [christian@brauner.io: adapt commit message to mention pidfds] Signed-off-by: Christian Brauner <christian@brauner.io>
2018-09-12udmabuf: add MEMFD_CREATE dependencyGerd Hoffmann
udmabuf builds without it, but if userspace can not create memfd handles in the first place it is rather pointless to include it, except for test builds. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20180911134216.9760-7-kraxel@redhat.com
2018-09-03Add udmabuf misc deviceGerd Hoffmann
A driver to let userspace turn memfd regions into dma-bufs. Use case: Allows qemu create dmabufs for the vga framebuffer or virtio-gpu ressources. Then they can be passed around to display those guest things on the host. To spice client for classic full framebuffer display, and hopefully some day to wayland server for seamless guest window display. qemu test branch: https://git.kraxel.org/cgit/qemu/log/?h=sirius/udmabuf Cc: David Airlie <airlied@linux.ie> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Daniel Vetter <daniel@ffwll.ch> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20180827093444.23623-1-kraxel@redhat.com
2016-10-25dma-buf: Rename struct fence to dma_fenceChris Wilson
I plan to usurp the short name of struct fence for a core kernel struct, and so I need to rename the specialised fence/timeline for DMA operations to make room. A consensus was reached in https://lists.freedesktop.org/archives/dri-devel/2016-July/113083.html that making clear this fence applies to DMA operations was a good thing. Since then the patch has grown a bit as usage increases, so hopefully it remains a good thing! (v2...: rebase, rerun spatch) v3: Compile on msm, spotted a manual fixup that I broke. v4: Try again for msm, sorry Daniel coccinelle script: @@ @@ - struct fence + struct dma_fence @@ @@ - struct fence_ops + struct dma_fence_ops @@ @@ - struct fence_cb + struct dma_fence_cb @@ @@ - struct fence_array + struct dma_fence_array @@ @@ - enum fence_flag_bits + enum dma_fence_flag_bits @@ @@ ( - fence_init + dma_fence_init | - fence_release + dma_fence_release | - fence_free + dma_fence_free | - fence_get + dma_fence_get | - fence_get_rcu + dma_fence_get_rcu | - fence_put + dma_fence_put | - fence_signal + dma_fence_signal | - fence_signal_locked + dma_fence_signal_locked | - fence_default_wait + dma_fence_default_wait | - fence_add_callback + dma_fence_add_callback | - fence_remove_callback + dma_fence_remove_callback | - fence_enable_sw_signaling + dma_fence_enable_sw_signaling | - fence_is_signaled_locked + dma_fence_is_signaled_locked | - fence_is_signaled + dma_fence_is_signaled | - fence_is_later + dma_fence_is_later | - fence_later + dma_fence_later | - fence_wait_timeout + dma_fence_wait_timeout | - fence_wait_any_timeout + dma_fence_wait_any_timeout | - fence_wait + dma_fence_wait | - fence_context_alloc + dma_fence_context_alloc | - fence_array_create + dma_fence_array_create | - to_fence_array + to_dma_fence_array | - fence_is_array + dma_fence_is_array | - trace_fence_emit + trace_dma_fence_emit | - FENCE_TRACE + DMA_FENCE_TRACE | - FENCE_WARN + DMA_FENCE_WARN | - FENCE_ERR + DMA_FENCE_ERR ) ( ... ) Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> Acked-by: Christian König <christian.koenig@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20161025120045.28839-1-chris@chris-wilson.co.uk
2016-08-15dma-buf/sw_sync: de-stage SW_SYNCGustavo Padovan
SW_SYNC allows to run tests on the sync_file framework via debugfs on <debugfs>/sync/sw_sync Opening and closing the file triggers creation and release of a sync timeline. To create fences on this timeline the SW_SYNC_IOC_CREATE_FENCE ioctl should be used. To increment the timeline value use SW_SYNC_IOC_INC. Also it exports Sync information on <debugfs>/sync/info Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-13dma-buf/sync_file: improve Kconfig description for Sync FilesGustavo Padovan
We've got a complaint saying that the description was quite obtuse and indeed it was. This patch tries to improve it. Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
2016-04-29dma-buf/sync_file: de-stage sync_fileGustavo Padovan
sync_file is useful to connect one or more fences to the file. The file is used by userspace to track fences between drivers that share DMA bufs. Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>