On Tue, 3 Mar 2009 09:55:27 -0500 (EST), Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 3 Mar 2009, Ming Lei wrote: > > > 2009/3/3 Cornelia Huck <cornelia.huck@xxxxxxxxxx>: > > > Hi, > > > > > > in thread [1], we discussed the issue of device_move() causing a > > > reordering of devices without adapting the ancestral order in dpm_list. > > > If a device is moved to a new parent that was registered after the > > > device itself, it would still be after its new parent in dpm_list, thus > > > causing the parent to be suspended before its child. > > > > > > This patchset attempts to remedy this situation by introducing an > > > interface for a driver to manipulate dpm_list with the dpm_list_mtx > > > held. (device_move() does not have enough information to do this > > > manipulation itself.) The calling sequence for a driver would be: > > > > > > - lock the dpm_list > > > - call device_move() > > > - if device_move() succeeded, fix up dpm_list > > > - unlock the dpm_list > > > > IMHO, It is better to fix up dpm_list inside device_move() , like device_add(), > > which may let s390, bluetooth or other possible users more happy with > > device_remove(). Maybe I'm a bit dense today, but I don't understand the problem with device_remove()? > > I agree; it would be cleaner if device_move() could fix up dpm_list > directly. If it doesn't have enough information to do so then change > the interface so that it does. That should be pretty easy since there > are only a handful of callers. The only really obvious one is 'move to NULL' -> 'move to end of dpm_list'. AFAICS, for that device_move() would need the following parameters: - device to be moved - new parent - which device to move in dpm_list (device, parent, or none) and then still the moves I do in the s390 code don't seem obvious for the driver core to get. Given that the callers still need to specify what to do, I find it much easier (and the resulting code much more understandable) if the callers fix up dpm_list... _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
