[PATCH v1] misc: fastrpc: Add support for userspace allocated buffers

[Dmitry Baryshkov]

On Fri, Jul 04, 2025 at 02:07:26PM +0530, Ekansh Gupta wrote:
> Support mapping userspace allocated buffers. If userspace allocates a
> buffer using rpcmem or DMABUF and sends it via a map request, fastrpc
> will map it to SMMU and DSP. Add support for both map and unmap
> requests.

Please start by describing a problem first, then the actions to solve
it.

> 
> Signed-off-by: Ekansh Gupta <ekansh.gupta at oss.qualcomm.com>
> ---
>  drivers/misc/fastrpc.c | 188 ++++++++++++++++++++++++++++++++---------
>  1 file changed, 150 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 378923594f02..3c88c8e9ba51 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1797,17 +1797,16 @@ static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
>  	return 0;
>  }
>  
> -static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, struct fastrpc_buf *buf)
> +static int fastrpc_req_munmap_dsp(struct fastrpc_user *fl, uintptr_t raddr, u64 size)

Please split the patch into two functional parts: one for refactoring
and one for the actual bugfix. It is pretty hard to follow the logic.

>  {
>  	struct fastrpc_invoke_args args[1] = { [0] = { 0 } };
>  	struct fastrpc_munmap_req_msg req_msg;
> -	struct device *dev = fl->sctx->dev;
>  	int err;
>  	u32 sc;
>  
>  	req_msg.client_id = fl->client_id;
> -	req_msg.size = buf->size;
> -	req_msg.vaddr = buf->raddr;
> +	req_msg.size = size;
> +	req_msg.vaddr = raddr;
>  
>  	args[0].ptr = (u64) (uintptr_t) &req_msg;
>  	args[0].length = sizeof(req_msg);

-- 
With best wishes
Dmitry