Re: [PATCH 4/8] i3c: master: Ensure Hot-Join operations are stopped on shutdown

[Adrian Hunter <adrian.hunter@intel.com>]

On 12/05/2026 19:27, Frank Li wrote:
> On Tue, May 12, 2026 at 03:17:28PM +0300, Adrian Hunter wrote:
>> System shutdown invokes each device's bus shutdown callback to quiesce
>> hardware, but the I3C bus type does not currently implement one.  As a
>> result, on shutdown the controller's Hot-Join work and any in-flight
>> i3c_master_do_daa() can keep running (or be newly triggered) while the
>> rest of the system is being torn down.
>>
>> A similar window exists at i3c_master_unregister() time: cancel_work_sync()
>> on hj_work prevents queued work from completing, but does not stop a
>> fresh Hot-Join IBI from re-queueing the worker, nor a concurrent sysfs
>> writer from toggling Hot-Join via i3c_set_hotjoin().
>>
>> Introduce a single "shutting down" gate in the I3C core, set under the
>> bus maintenance lock so it is observed by any in-progress DAA path
>> before pending work is cancelled.  Install an i3c_bus_type shutdown
>> callback that engages this gate for master devices during system
>> shutdown, and use the same gate in i3c_master_unregister() so both
>> paths get identical guarantees.
>>
>> Once the gate is engaged, the Hot-Join worker, i3c_master_do_daa_ext()
>> and i3c_set_hotjoin() all bail out cleanly, so Hot-Join IBIs that race
>> with shutdown become no-ops, direct DAA callers see -ENODEV, and sysfs
>> writers can no longer re-enable Hot-Join through ops->enable_hotjoin()
>> while the controller is going away.
>>
>> No functional change for the steady-state runtime path; the new checks
>> only take effect once the controller has been marked as shutting down.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>>  drivers/i3c/master.c       | 52 +++++++++++++++++++++++++++-----------
>>  include/linux/i3c/master.h |  2 ++
>>  2 files changed, 39 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
>> index cdb5cb2aa65d..a59c4b744b36 100644
>> --- a/drivers/i3c/master.c
>> +++ b/drivers/i3c/master.c
>> @@ -368,14 +368,6 @@ static void i3c_device_remove(struct device *dev)
>>  		driver->remove(i3cdev);
>>  }
>>
>> -const struct bus_type i3c_bus_type = {
>> -	.name = "i3c",
>> -	.match = i3c_device_match,
>> -	.probe = i3c_device_probe,
>> -	.remove = i3c_device_remove,
>> -};
>> -EXPORT_SYMBOL_GPL(i3c_bus_type);
>> -
> 
> why need move this tunk?

To avoid forward declarations.

i3c_device_shutdown() references i3c_masterdev_type so it needs to be
after i3c_masterdev_type definition.  i3c_device_shutdown() is being
added to struct i3c_bus_type, so i3c_bus_type needs to be after
i3c_device_shutdown().

> 
>>  static enum i3c_addr_slot_status
>>  i3c_bus_get_addr_slot_status_mask(struct i3c_bus *bus, u16 addr, u32 mask)
>>  {
>> @@ -637,7 +629,8 @@ static void i3c_master_hj_work_fn(struct work_struct *work)
>>  {
>>  	struct i3c_master_controller *master = container_of(work, typeof(*master), hj_work);
>>
>> -	i3c_master_do_daa(master);
>> +	if (!master->shutting_down)
>> +		i3c_master_do_daa(master);
>>  }
>>
>>  static int i3c_set_hotjoin(struct i3c_master_controller *master, bool enable)
>> @@ -658,7 +651,9 @@ static int i3c_set_hotjoin(struct i3c_master_controller *master, bool enable)
>>
>>  	i3c_bus_maintenance_lock(&master->bus);
> 
> later, consider change to use cleanup, so
> 	if (master->shutting_down)
> 		return -ENODEV
> 
> 	and avoid use else if branch.
> 
> but this change is okay for now.
> 
> Frank