Is there some implicit locking of device methods?

[John Baldwin]

On Tuesday, April 26, 2011 8:17:09 pm Bartosz Fabianowski wrote:
> > If you needs per-file private data for cdev, you would be better served
> > by cdevpriv(9) KPI. Cloning is too hard to use correctly for such task.
> 
> Thanks, I just got that working. To help those going down a similar path 
> in the future, I would like to note quickly that the following must be 
> added to the cdevsw structure to ensure proper clean-up:
> 
> .d_flags = D_TRACKCLOSE
> 
> I just spent hours debugging panics until I realized only the last 
> close() was triggering a call to my .d_close method.

Err, if you use cdevpriv you shouldn't even have a d_close method.  All your 
d_close logic should be in the cdevpriv destructor, and the kernel will call 
your destructor when all references to an open file descriptor go away (i.e. 
it is closed).

-- 
John Baldwin