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Commitbdb8d06dfe("dmabuf: Add the capability to expose DMA-BUF stats in sysfs") added dmabuf statistics to sysfs in 2021 under CONFIG_DMABUF_SYSFS_STATS. After being used in production, performance problems were discovered leading to its deprecation in 2022 in commite0a9f1fe20("dma-buf: deprecate DMABUF_SYSFS_STATS"). Some of the problems with this interface were discussed in my LPC 2025 talk. [1][2] Android was probably the last user of the interface, which has since been migrated to use the dmabuf BPF iterator [3] to obtain the same information more cheaply. As promised in that series, now that the longterm stable 6.18 kernel has been released let's remove the sysfs dmabuf statistics from the kernel. [1] https://www.youtube.com/watch?v=D83qygudq9c [2] https://lpc.events/event/19/contributions/2118/ [3] https://lore.kernel.org/all/20250522230429.941193-1-tjmercier@google.com/ Signed-off-by: T.J. Mercier <tjmercier@google.com> Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: https://patch.msgid.link/20260116190517.3268458-1-tjmercier@google.com
80 lines
2.6 KiB
Text
80 lines
2.6 KiB
Text
# SPDX-License-Identifier: GPL-2.0-only
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menu "DMABUF options"
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config SYNC_FILE
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bool "Explicit Synchronization Framework"
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default n
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select DMA_SHARED_BUFFER
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help
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The Sync File Framework adds explicit synchronization via
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userspace. It enables send/receive 'struct dma_fence' objects to/from
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userspace via Sync File fds for synchronization between drivers via
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userspace components. It has been ported from Android.
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The first and main user for this is graphics in which a fence is
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associated with a buffer. When a job is submitted to the GPU a fence
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is attached to the buffer and is transferred via userspace, using Sync
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Files fds, to the DRM driver for example. More details at
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Documentation/driver-api/sync_file.rst.
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config SW_SYNC
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bool "Sync File Validation Framework"
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default n
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depends on SYNC_FILE
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depends on DEBUG_FS
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help
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A sync object driver that uses a 32bit counter to coordinate
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synchronization. Useful when there is no hardware primitive backing
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the synchronization.
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WARNING: improper use of this can result in deadlocking kernel
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drivers from userspace. Intended for test and debug only.
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config UDMABUF
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bool "userspace dmabuf misc driver"
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default n
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depends on DMA_SHARED_BUFFER
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depends on MEMFD_CREATE || COMPILE_TEST
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depends on MMU
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help
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A driver to let userspace turn memfd regions into dma-bufs.
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Qemu can use this to create host dmabufs for guest framebuffers.
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config DMABUF_MOVE_NOTIFY
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bool "Move notify between drivers (EXPERIMENTAL)"
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default n
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depends on DMA_SHARED_BUFFER
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help
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Don't pin buffers if the dynamic DMA-buf interface is available on
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both the exporter as well as the importer. This fixes a security
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problem where userspace is able to pin unrestricted amounts of memory
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through DMA-buf.
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This is marked experimental because we don't yet have a consistent
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execution context and memory management between drivers.
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config DMABUF_DEBUG
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bool "DMA-BUF debug checks"
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depends on DMA_SHARED_BUFFER
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default y if DEBUG
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help
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This option enables additional checks for DMA-BUF importers and
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exporters. Specifically it validates that importers do not peek at the
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underlying struct page when they import a buffer.
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config DMABUF_SELFTESTS
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tristate "Selftests for the dma-buf interfaces"
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default n
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depends on DMA_SHARED_BUFFER
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menuconfig DMABUF_HEAPS
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bool "DMA-BUF Userland Memory Heaps"
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select DMA_SHARED_BUFFER
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help
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Choose this option to enable the DMA-BUF userland memory heaps.
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This options creates per heap chardevs in /dev/dma_heap/ which
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allows userspace to allocate dma-bufs that can be shared
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between drivers.
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source "drivers/dma-buf/heaps/Kconfig"
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endmenu
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