[PATCH v4 0/4] misc: fastrpc: Add missing bug fixes

[Jianping Li <jianping.li@oss.qualcomm.com>]

Add missing bug fixes in memory areas. This patch series fixes multiple memory handling issues in the FastRPC
driver, primarily around the Audio PD remote heap.

The Audio PD uses a reserved memory-region that is shared between HLOS
and the DSP. Allocating and freeing this memory from userspace is unsafe,
as the kernel cannot reliably determine when the DSP has finished using
the buffers.

To address this, the entire reserved memory-region for the Audio PD is
now fully assigned to the DSP during remoteproc boot-up, and its lifetime
is tied to the rpmsg channel.

Patch [v3]: https://lore.kernel.org/all/20260407100508.1027-1-jianping.li@oss.qualcomm.com/

Change in v4:
  - Fail Audio PD static process creation when no reserved memory-region
    is present, instead of silently proceeding

Change in v3:
  - Adjusted the order of the series, placing NULL check changes that are not bug fixes at the end
  - Modified the commit message to describe the bug background in detail
  - Switch buf->list_lock back to fl->lock
  - Add locking to the operation of audio_init_mem

Changes in v2:
  - Remove the if check outside fastrpc_buf_free
  - Store the spinlock pointer in the struct fastrpc_buf instead
  - Allocate entire reserved memory to audio PD through remote heap

Ekansh Gupta (3):
  misc: fastrpc: Fix initial memory allocation for Audio PD memory pool
  misc: fastrpc: Remove buffer from list prior to unmap operation
  misc: fastrpc: Allow fastrpc_buf_free() to accept NULL

Jianping Li (1):
  misc: fastrpc: Allocate entire reserved memory for Audio PD in probe

 drivers/misc/fastrpc.c | 136 ++++++++++++++++++++++-------------------
 1 file changed, 74 insertions(+), 62 deletions(-)

-- 
2.43.0