Re: BlueZ/mesh: RX not working after daemon restart (with workaround)

[Steve Brown <sbrown@ewol.com>]

On Sun, 2019-11-10 at 21:08 +0100, Aurelien Jarno wrote:
> Hi all,
> 
> On my system (Raspberry PI 3), the RX path doesn't work anymore
> following a restart of the bluetooth-meshd daemon. I have tracked
> down
> that to the fact that the receive callbacks are setup before the HCI
> is
> fully initialized. Said otherwise, BT_HCI_CMD_LE_SET_SCAN_PARAMETERS
> is
> called before BT_HCI_CMD_RESET and the callback calling
> BT_HCI_CMD_LE_SET_SCAN_ENABLE is not called. This timing dependent
> and
> probably not reproducible on all hardware.
> 
> I have workarounded the issue by adding a small delay between the HCI
> initialization and the call to node_attach_io_all():
> 
> diff --git a/mesh/mesh.c b/mesh/mesh.c
> index 9b2b2073b..1c06060f9 100644
> --- a/mesh/mesh.c
> +++ b/mesh/mesh.c
> @@ -167,6 +167,10 @@ bool mesh_init(const char *config_dir, enum
> mesh_io_type type, void *opts)
>  	mesh_io_get_caps(mesh.io, &caps);
>  	mesh.max_filters = caps.max_num_filters;
>  
> +	for (int i = 0 ; i < 100 ; i++) {
> +		l_main_iterate(10);
> +	}
> +
>  	node_attach_io_all(mesh.io);
>  
>  	return true;
> 
> I guess there is a better way to do that by waiting for the HCI to be
> fully initialized before calling node_attach_io_all() or by using a
> callback instead. However I do not know the codebase good enough to
> fix
> that properly.
> 
> Aurelien
> 
I've experienced something similar on my rpi3. I found that on restart,
discover-unprovisioned stopped working.

In my case, it appears that meshd assumes that if there are existing
nodes, scanning has been enabled. Thus, calls from mesh-cfgclient to
discover additional unprovisioned nodes do not need another hci scan
enable at mesh/mesh-io-generic.c:736.

If meshd is restarted with preexisting nodes, scanning is still assumed
to already be enabled, but it's not. This breaks discover-unprovisioned 
for me.

I suspect this is a symptom of a deeper problem where mesh/mesh-config-
json.c:load_node doesn't completely reestablish the node state that
existed when the node was originally added.

Steve