On Wed, Mar 26, 2014 at 09:40:18PM +0100, Thomas Hellstrom wrote: > On 03/26/2014 08:08 PM, David Herrmann wrote: > > "struct_mutex" is used to serialize all entry-points into > > the drm-device (and thus the driver) and also, often implicitly, as > > spin-lock for "struct drm_device" data protection. > > No. DRM locking was added as an after-though, and is a horrendous mess. > Nobody really knows what's protecting what, and that has caused a lot of > grief in the past. Probably most so for the Intel driver that relied > (relies?) on the struct_mutex to protect everything. The > drm_global_mutex is used to serialize the non-lock-audited entry points > into the drm device. The struct_mutex is used for data protection of > most core drm structures and serializing here and there. Modern drivers > have no locks held when entering their ioctls. Also we should not > confuse mutexes and spinlocks in this context, as they have very > different semantics. As the guy who gets to live the locking mess called dev->struct_mutex I holeheartedly welcome any efforts to split out clear subparts away from it. I actually had this very idea of adding a master-data related mutex on my todo. I'll try to review this later if I get around, but definitely Acked! -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
