linux/drivers/dma-buf
Charan Teja Kalla 370704e707 dma-buf: ensure unique directory name for dmabuf stats
The dmabuf file uses get_next_ino()(through dma_buf_getfile() ->
alloc_anon_inode()) to get an inode number and uses the same as a
directory name under /sys/kernel/dmabuf/buffers/<ino>. This directory is
used to collect the dmabuf stats and it is created through
dma_buf_stats_setup(). At current, failure to create this directory
entry can make the dma_buf_export() to fail.

Now, as the get_next_ino() can definitely give a repetitive inode no
causing the directory entry creation to fail with -EEXIST. This is a
problem on the systems where dmabuf stats functionality is enabled on
the production builds can make the dma_buf_export(), though the dmabuf
memory is allocated successfully, to fail just because it couldn't
create stats entry.

This issue we are able to see on the snapdragon system within 13 days
where there already exists a directory with inode no "122602" so
dma_buf_stats_setup() failed with -EEXIST as it is trying to create
the same directory entry.

To make the dentry name as unique, use the dmabuf fs specific inode
which is based on the simple atomic variable increment. There is tmpfs
subsystem too which relies on its own inode generation rather than
relying on the get_next_ino() for the same reason of avoiding the
duplicate inodes[1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/patch/?id=e809d5f0b5c912fe981dce738f3283b2010665f0

Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: <stable@vger.kernel.org> # 5.15.x+
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1652441296-1986-1-git-send-email-quic_charante@quicinc.com
Signed-off-by: Christian König <christian.koenig@amd.com>
2022-05-13 13:35:10 +02:00
..
heaps dma-buf-map: Rename to iosys-map 2022-02-07 16:35:35 -08:00
dma-buf-sysfs-stats.c kobject: remove kset from struct kset_uevent_ops callbacks 2021-12-28 11:26:18 +01:00
dma-buf-sysfs-stats.h dma-buf: Delete the DMA-BUF attachment sysfs statistics 2021-07-20 11:06:59 +02:00
dma-buf.c dma-buf: ensure unique directory name for dmabuf stats 2022-05-13 13:35:10 +02:00
dma-fence-array.c dma-buf: handle empty dma_fence_arrays gracefully 2022-03-29 09:14:30 +02:00
dma-fence-chain.c dma-buf: add dma_fence_chain_contained helper 2022-02-08 09:25:16 +01:00
dma-fence.c dma-buf: add dma_fence_describe and dma_resv_describe v2 2021-11-11 09:35:13 +01:00
dma-heap.c dma-buf: heaps: Fix potential spectre v1 gadget 2022-02-01 13:18:09 +05:30
dma-resv.c dma-buf: warn about containers in dma_resv object 2022-02-08 09:21:10 +01:00
Kconfig dma-buf: DMABUF_SYSFS_STATS should depend on DMA_SHARED_BUFFER 2021-09-07 12:42:21 +05:30
Makefile dma-buf: add dma_fence_unwrap v2 2022-03-25 14:18:28 +01:00
selftest.c
selftest.h
selftests.h dma-buf: add dma_fence_unwrap v2 2022-03-25 14:18:28 +01:00
st-dma-fence-chain.c dma-buf: add dma_fence_chain_alloc/free v3 2021-06-14 19:38:34 +02:00
st-dma-fence-unwrap.c dma-buf: add dma_fence_unwrap v2 2022-03-25 14:18:28 +01:00
st-dma-fence.c dma-buf: Avoid comma separated statements 2021-02-09 17:14:11 +01:00
st-dma-resv.c dma-buf: drop excl_fence parameter from dma_resv_get_fences 2022-01-19 10:03:56 +01:00
sw_sync.c
sync_debug.c
sync_debug.h
sync_file.c dma-buf/sync-file: fix logic error in new fence merge code 2022-03-29 09:14:10 +02:00
sync_trace.h
udmabuf.c udmabuf: validate ubuf->pagecount 2022-01-18 07:52:41 +01:00