1) It is not useful to call "devfs_clear_cdevpriv()" from
"d_close" callbacks, hence for example read, write, ioctl and
so on might be sleeping at the time of "d_close" being called
and then then freed private data can still be accessed.
Examples: dtrace, linux_compat, ksyms (all fixed by this patch)
2) In sys/dev/drm* there are some cases in which memory will
be freed twice, if open fails, first by code in the open
routine, secondly by the cdevpriv destructor. Move registration
of the cdevpriv to the end of the drm open routines.
3) devfs_clear_cdevpriv() is not called if the "d_open" callback
registered cdevpriv data and the "d_open" callback function
returned an error. Fix this.
Discussed with: phk
MFC after: 2 weeks
On systems with HZ=100 it caused Intel eDP video output initialization
(and Xorg startup) to take several minutes instead of several seconds.
Reviewed by: kib
MFC after: 3 days
since batch_len is unused by Linux driver, it seems that it is sometimes
gets passed wrong. This causes command buffer corruption and GPU hung.
Old GEMified DDX drivers that needs this workaround are not supported.
MFC after: 1 month
works with new generations of GPUs (IronLake, SandyBridge and
supposedly IvyBridge).
The driver is not connected to the build yet.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
