Re: [PATCH] drivers: base: Set mod->async_probe_requested if needed

["Danilo Krummrich" <dakr@kernel.org>]

On Tue Apr 7, 2026 at 6:05 PM CEST, Bart Van Assche wrote:
> If PROBE_PREFER_ASYNCHRONOUS is set for a device driver, and if loading
> other kernel modules depends on probing of that device driver to
> complete, e.g. because it is a storage driver, and if
> mod->async_probe_requested has not been set, then the
> async_synchronize_full() call in do_init_module() introduces a delay.
> Fix this by setting mod->async_probe_requested if
> PROBE_PREFER_ASYNCHRONOUS has been set. This patch reduces the Pixel 10
> boot time by 100 ms.
>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Petr Pavlu <petr.pavlu@suse.com>
> Cc: Daniel Gomez <da.gomez@kernel.org>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Aaron Tomlin <atomlin@atomlin.com>
> Cc: Igor Pylypiv <ipylypiv@google.com>
> Cc: Chung-Kai Mei <chungkai@google.com>
> Cc: stable@vger.kernel.org

Why does this have Cc: stable? I think this is just an improvement and not a
regression? If it is a regression, what's the commit that is fixed?

> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/base/module.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/base/module.c b/drivers/base/module.c
> index 218aaa096455..e58fc189d389 100644
> --- a/drivers/base/module.c
> +++ b/drivers/base/module.c
> @@ -39,6 +39,9 @@ int module_add_driver(struct module *mod, const struct device_driver *drv)
>  	if (!drv)
>  		return 0;
>  
> +	if (mod && drv->probe_type == PROBE_PREFER_ASYNCHRONOUS)
> +		mod->async_probe_requested = true;

What if userspace did explicitly pass async_probe=0?

> +
>  	if (mod)
>  		mk = &mod->mkobj;
>  	else if (drv->mod_name) {