RE: [PATCH v2 2/3] iommufd/device: Make hwpt_list list_add/del symmetric

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Sunday, January 29, 2023 5:18 AM
> 
> Since the list_del() of hwpt_item is done in iommufd_device_detach(), move
> its list_add_tail() to a similar place in iommufd_device_do_attach().

It's clearer to say that because list_del() is together with
iopt_table_remove_domain() then it makes sense to have list_add_tail()
together with iopt_table_add_domain().

> 
> Also move and place the mutex outside the
> iommufd_device_auto_get_domain()
> and iommufd_device_do_attach() calls, to serialize attach/detach routines.
> This adds an additional locking protection so that the following patch can
> safely remove devices_lock.
> 
> Co-developed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>