On Fri, Mar 17, 2006 at 03:16:58PM -0600, Kumar Gala wrote: > > On Mar 17, 2006, at 12:54 PM, Kumar Gala wrote: > > >I'm looking at porting the i2c-virtual code from 2.4 to 2.6. One > >thing I'm not clear on is the use of i2c_add_adapter_nolock() by > >the old code. The only reference I can find related to this is: > > > >http://archives.andrew.net.au/lm-sensors/msg31060.html > > > >I can't think of a reason why locking would be in issue when adding > >or removing of a virtual adapter. Anyone have an additional ides > >on this? > > Ok, so I figured out why the _nolock() versions exist. In > i2c_driver_register we take the core_list lock. Eventually we will > call i2c_probe() which should call driver->attach_adapter(). For a > virtual bus the driver's attach_adapter() will end up calling > i2c_virt_create_adapter() which will end up calling i2c_add_adapter() > which will never get the core_list lock. > > So should we integrate the concept of virtual adapters into the i2c > core and have it such that i2c_virt_create_adapter()/ > i2c_virt_remove_adapter() expects the caller to have the core_list > lock already? Possibly. Jean, what do you think? thanks, greg k-h
