[PATCH 0/1] [RFC] DRM locking issues during early open
airlied at gmail.com
Fri Apr 20 03:34:43 PDT 2012
> I may be reading things wrong but the initialisation does indeed hold
> drm_global_mutex, but and back when this first occured we would have
> been using kernel_lock() which was at least partially reentrant right?
Yup if we slept with the BKL held we'd have allowed others to get past it,
but also I introduced the global mutex in pci a while back
Author: Dave Airlie <airlied at redhat.com>
Date: Tue Sep 14 20:14:38 2010 +1000
drm: fix race between driver loading and userspace open.
Not 100% sure this is due to BKL removal, its most likely a combination
of that + userspace timing changes in udev/plymouth. The drm adds the sysfs
device before the driver has completed internal loading, this causes udev
to make the node and plymouth to open it before we've completed loading.
The proper solution is to delay the sysfs manipulation until later
however this causes knock on issues with sysfs connector nodes, so
we can use
the global mutex to serialise loading and userspace opens.
Reported-by: Toni Spets (hifi on #radeon)
Signed-off-by: Dave Airlie <airlied at redhat.com>
by a while I mean nearly 1.5 yrs ago, with the intent of fixing it this way.
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