[PATCH v8 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 [v7]: https://lore.kernel.org/all/20260602071750.526-1-jianping.li@oss.qualcomm.com/

Change in v8:
  - Squashed "Fail Audio PD init when reserved memory is missing" into
    "Allocate entire reserved memory for Audio PD in probe" as the
    validation check depends on the probe allocation
  - Fixed error path in probe: use goto err_free_data instead of bare
    return when kzalloc_obj fails
  - Added kfree(data->remote_heap) in err_free_data path
  - Made kfree(cctx->remote_heap) unconditional in rpmsg_remove,
    not tied to vmcount or qcom_scm_assign_mem result
  - Used local cctx variable consistently instead of fl->cctx

Change in v7:
  - Removed duplicate remote heap validation check; keep it only at
    the beginning of fastrpc_init_create_static_process()

Change in v6:
  - Separate the handling of err_copy
  - Place the check for remote_heap at the beginning of the function

Change in v5:
  - Split reserved-memory handling into separate patches

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 | 137 ++++++++++++++++++++++-------------------
 1 file changed, 75 insertions(+), 62 deletions(-)

-- 
2.43.0