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FROMLIST: misc: fastrpc: Add missing bug fixes#498

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Jianping-Li wants to merge 4 commits intoqualcomm-linux:qcom-6.18.yfrom
Jianping-Li:remote_heap
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FROMLIST: misc: fastrpc: Add missing bug fixes#498
Jianping-Li wants to merge 4 commits intoqualcomm-linux:qcom-6.18.yfrom
Jianping-Li:remote_heap

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This patch series adds the listed bug fixes that have been missing in QLI2.0 fastRPC driver.
following fixes:

Add multiple fixes for remote heap which is used by Audio PD.
Add safety checks to fastrpc_buf_free
Link: https://lore.kernel.org/all/20260407100508.1027-1-jianping.li@oss.qualcomm.com/

CRs-Fixed: 4483711

ekanshibu and others added 4 commits April 21, 2026 17:17
…emory pool

The initial buffer allocated for the Audio PD memory pool is never added
to the pool because pageslen is set to 0. As a result, the buffer is not
registered with Audio PD and is never used, causing a memory leak. Audio
PD immediately falls back to allocating memory from the remote heap since
the pool starts out empty.

Fix this by setting pageslen to 1 so that the initially allocated buffer
is correctly registered and becomes part of the Audio PD memory pool.

Link: https://lore.kernel.org/all/20260407100508.1027-2-jianping.li@oss.qualcomm.com/
Fixes: 0871561 ("misc: fastrpc: Add support for audiopd")
Cc: stable@kernel.org
Co-developed-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
…tion

fastrpc_req_munmap_impl() is called to unmap any buffer. The buffer is
getting removed from the list after it is unmapped from DSP. This can
create potential race conditions if any other thread removes the entry
from list while unmap operation is ongoing. Remove the entry before
calling unmap operation.

Link: https://lore.kernel.org/all/20260409062617.1182-3-jianping.li@oss.qualcomm.com/
Fixes: 2419e55 ("misc: fastrpc: add mmap/unmap support")
Cc: stable@kernel.org
Co-developed-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
… in probe

Allocating and freeing Audio PD memory from userspace is unsafe because
the kernel cannot reliably determine when the DSP has finished using the
memory. Userspace may free buffers while they are still in use by the DSP,
and remote free requests cannot be safely trusted.

Allocate the entire Audio PD reserved-memory region upfront during rpmsg
probe and tie its lifetime to the rpmsg channel. This avoids userspace-
controlled alloc/free and ensures memory is reclaimed only when the DSP
shuts down.

Link: https://lore.kernel.org/all/20260409062617.1182-4-jianping.li@oss.qualcomm.com/
Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
Make fastrpc_buf_free() a no-op when passed a NULL pointer, allowing
callers to avoid open-coded NULL checks.

Link: https://lore.kernel.org/all/20260409062617.1182-5-jianping.li@oss.qualcomm.com/
Co-developed-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
Signed-off-by: Jianping Li <jianping.li@oss.qualcomm.com>
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2 participants