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

[Vinod Koul <vkoul@kernel.org>]

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@opensource.cirrus.com>
> ---
> 
> 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

-- 
~Vinod