Re: [PATCH 1/2] soundwire: bus: Don't unassign dev_num before unregistering device

[Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>]

On 9/11/26 18:19, Charles Keepax wrote:
> Don't mark dev_num as unassigned until after device_unregister()
> 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.

That change looks fine.

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>

But I am a bit worried about the dev_num handling now that I think of
it. This is *only* at the manager level. At the peripheral level, the
dev_num register has not been modified so the hardware still reports as
ATTACHED with the dev_num whose mask was cleared on the host side.
IOW we have a zombie peripheral on the link, and if we do a sequence
rmmod/insmod things could be fun...
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> ---
>  drivers/soundwire/bus.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> index aeaae5a57c89d..b17718f4277ed 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_unregister(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 +186,6 @@ static int sdw_delete_slave(struct device *dev, void *data)
>  	list_del_init(&slave->node);
>  	mutex_unlock(&bus->bus_lock);
>  
> -	device_unregister(dev);
>  	return 0;
>  }
>