Re: [PATCH] driver core: Add cmdline option to force probe type

[Jianlin Lv]

On Thu, May 14, 2026 at 6:16 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, May 14, 2026 at 05:49:55PM +0800, Jianlin Lv wrote:
> > From: Jianlin Lv <iecedge@xxxxxxxxx>
> >
> > Device drivers that use asynchronous probing can cause non-deterministic
> > device ordering and naming across reboots. A typical example is storage
> > drivers (like sd/nvme): asynchronous probing can lead to inconsistent disk
> > logical names after reboot. In scenarios where disk naming consistency is
> > critical, the probe type should be set to synchronous.
> >
> > This patch introduces a driver_probe kernel parameter that overrides any
> > driver's hard-coded probe type settings and allows runtime control without
> > requiring kernel recompilation:
> >
> >   driver_probe=PROBE_TYPE_SYNC,nvme,sd      # Force specific drivers sync
> >   driver_probe=PROBE_TYPE_ASYNC,*,usb       # Force all async except usb
> >   driver_probe=PROBE_TYPE_SYNC,*            # Force all drivers synchronous
> >
> > The implementation replaces the limited driver_async_probe parameter with
> > a more flexible interface that can force either synchronous or asynchronous
> > probing as needed.
> >
> > Signed-off-by: Jianlin Lv <iecedge@xxxxxxxxx>
> > ---
> >  .../admin-guide/kernel-parameters.txt         | 27 +++++--
> >  drivers/base/dd.c                             | 71 ++++++++++++++-----
> >  2 files changed, 74 insertions(+), 24 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 4d0f545fb3ec..b43a8bd20356 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -1377,12 +1377,27 @@ Kernel parameters
> >                       it becomes active and is searched during signature
> >                       verification.
> >
> > -     driver_async_probe=  [KNL]
> > -                     List of driver names to be probed asynchronously. *
> > -                     matches with all driver names. If * is specified, the
> > -                     rest of the listed driver names are those that will NOT
> > -                     match the *.
> > -                     Format: <driver_name1>,<driver_name2>...
>
> You can not remove an existing user/kernel api, sorry, that is not
> allowed as you just broke all systems that were relying on this :(
>
Could you provide more suggestions on how to improve this patch?
If extend driver_async_probe to implement a 'force synchronous probe'
feature, that doesn’t really match the name driver_async_probe and
may feel ambiguous.
If  add a new 'driver_probe' parameter while keeping driver_async_probe,
then their functionality would partially overlap.

Regards,
Jianlin

> thanks,
>
> greg k-h