Re: [PATCH v2 1/3] soundwire: bus: Don't unassign dev_num before unregistering device

[Charles Keepax]

On Sat, Oct 03, 2026 at 10:18:02AM +0200, Vinod Koul wrote:
> On 25-09-26, 16:42, Charles Keepax wrote:
> > Don't mark dev_num as unassigned until after the driver remove has
> > been called. The driver may want to communicate with the device
> > as part of the driver remove operation, so the dev_num should
> > remain assigned until that has completed. This requires moving from
> > device_unregister() to manually calling device_del() and device_put()
> > to ensure that the slave struct isn't freed too early.
> > 
> > Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> > 
> > Changes since v1:
> >  - Split device_unregister into device_del and put_device
> > 
> >  drivers/soundwire/bus.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> > index aeaae5a57c89d..1488b6540844c 100644
> > --- a/drivers/soundwire/bus.c
> > +++ b/drivers/soundwire/bus.c
> > @@ -175,8 +175,9 @@ static int sdw_delete_slave(struct device *dev, void *data)
> >  
> >  	sdw_slave_debugfs_exit(slave);
> >  
> > -	mutex_lock(&bus->bus_lock);
> > +	device_del(dev);
> >  
> > +	mutex_lock(&bus->bus_lock);
> >  	if (slave->dev_num) { /* clear dev_num if assigned */
> >  		clear_bit(slave->dev_num, bus->assigned);
> >  		if (bus->ops && bus->ops->put_device_num)
> > @@ -185,7 +186,8 @@ static int sdw_delete_slave(struct device *dev, void *data)
> >  	list_del_init(&slave->node);
> >  	mutex_unlock(&bus->bus_lock);
> >  
> > -	device_unregister(dev);
> > +	put_device(dev);
> 
> if we are doing this I would add code comments on why we split. We
> invoke device_register so the expectation is that we always call
> device_unregister. I understand this is being done but this needs to be
> well documented here

Yeah that is a good idea I will update.

Thanks,
Charles