621f94a601
This patch allows statistics to be enabled for each DMA-BUF in sysfs by enabling the config CONFIG_DMABUF_SYSFS_STATS. The following stats will be exposed by the interface: /sys/kernel/dmabuf/buffers/<inode_number>/exporter_name /sys/kernel/dmabuf/buffers/<inode_number>/size /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/device /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/map_counter The inode_number is unique for each DMA-BUF and was added earlier [1] in order to allow userspace to track DMA-BUF usage across different processes. Currently, this information is exposed in /sys/kernel/debug/dma_buf/bufinfo. However, since debugfs is considered unsafe to be mounted in production, it is being duplicated in sysfs. This information will be used to derive DMA-BUF per-exporter stats and per-device usage stats for Android Bug reports. The corresponding userspace changes can be found at [2]. Telemetry tools will also capture this information(along with other memory metrics) periodically as well as on important events like a foreground app kill (which might have been triggered by Low Memory Killer). It will also contribute to provide a snapshot of the system memory usage on other events such as OOM kills and Application Not Responding events. A shell script that can be run on a classic Linux environment to read out the DMA-BUF statistics can be found at [3](suggested by John Stultz). The patch contains the following improvements over the previous version: 1) Each attachment is represented by its own directory to allow creating a symlink to the importing device and to also provide room for future expansion. 2) The number of distinct mappings of each attachment is exposed in a separate file. 3) The per-buffer statistics are now in /sys/kernel/dmabuf/buffers inorder to make the interface expandable in future. All of the improvements above are based on suggestions/feedback from Daniel Vetter and Christian König. [1]: https://lore.kernel.org/patchwork/patch/1088791/ [2]: https://android-review.googlesource.com/q/topic:%22dmabuf-sysfs%22+(status:open%20OR%20status:merged) [3]: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/1549734 Bug: 167709539 Link: https://lore.kernel.org/linux-media/20210126204240.418297-1-hridya@google.com/ [hridya: minor rebase needed in include/linux/dma-buf.h for backporting] Signed-off-by: Hridya Valsaraju <hridya@google.com> Reported-by: kernel test robot <lkp@intel.com> Change-Id: I8a3342b57f2e21ff349839f5cf665980c97bf849
81 lines
2.6 KiB
Plaintext
81 lines
2.6 KiB
Plaintext
# 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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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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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_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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menuconfig DMABUF_SYSFS_STATS
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bool "DMA-BUF sysfs statistics"
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select DMA_SHARED_BUFFER
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help
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Choose this option to enable DMA-BUF sysfs statistics
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in location /sys/kernel/dmabuf/buffers.
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/sys/kernel/dmabuf/buffers/<inode_number> will contain
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statistics for the DMA-BUF with the unique inode number
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<inode_number>.
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source "drivers/dma-buf/heaps/Kconfig"
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endmenu
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