Locking question for DRM
alan at lxorguk.ukuu.org.uk
Fri Apr 23 03:37:17 PDT 2010
> > and I can't see what makes this safe if the drm_release for the master
> > and a client occur at the same time ?
> lock_kernel in drm_release. We probably need to clean that up.
I don't think that works. drm_open_helper doesn't appear to be under the
BKL merely the struct mutex.
> > The setmaster/dropmaster ioctl seems similar - the various conditional
> > checks are not protected from parallel changes occuring during their
> > execution.
> > Is this a bug or is something clever afoot ?
> These ioctls are also under the BKL.
But setmaster can sleep so the BKL is dropped on contention of the
struct_mutex, ditto dropmaster
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