On Sat, May 17, 2025 at 12:54:32PM +0530, Ekansh Gupta wrote:
> During rpmsg_probe, fastrpc device nodes are created first, then
> channel specific resources are initialized, followed by
> of_platform_populate, which triggers context bank probing. This
> sequence can cause issues as applications might open the device
> node before channel resources are initialized or the session is
> available, leading to problems. For example, spin_lock is initialized
> after the device node creation, but it is used in device_open,
> potentially before initialization. Add a check in device_open for
> rpdev and update rpdev at the end of rpmsg_probe to resources are
> available before applications allocate sessions.
Can we fix this by registering the device node after initializing
channel resources?
>
> Fixes: f6f9279f2bf0e ("misc: fastrpc: Add Qualcomm fastrpc basic driver
> model")
> Cc: sta...@kernel.org
> Signed-off-by: Ekansh Gupta <ekansh.gu...@oss.qualcomm.com>
> ---
> drivers/misc/fastrpc.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 7b7a22c91fe4..40c7fa048ba7 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -1568,6 +1568,9 @@ static int fastrpc_device_open(struct inode *inode,
> struct file *filp)
> fdevice = miscdev_to_fdevice(filp->private_data);
> cctx = fdevice->cctx;
>
> + if (!cctx->rpdev)
> + return -ENODEV;
> +
> fl = kzalloc(sizeof(*fl), GFP_KERNEL);
> if (!fl)
> return -ENOMEM;
> @@ -2363,12 +2366,13 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device
> *rpdev)
> spin_lock_init(&data->lock);
> idr_init(&data->ctx_idr);
> data->domain_id = domain_id;
> - data->rpdev = rpdev;
>
> err = of_platform_populate(rdev->of_node, NULL, NULL, rdev);
> if (err)
> goto populate_error;
>
> + data->rpdev = rpdev;
> +
> return 0;
>
> populate_error:
> --
> 2.34.1
>
--
With best wishes
Dmitry
