From b1e3177bd1d8f41e2a9cc847e56a96cdc0eefe62 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 4 Oct 2019 14:40:00 +0100 Subject: drm/i915: Coordinate i915_active with its own mutex Forgo the struct_mutex serialisation for i915_active, and interpose its own mutex handling for active/retire. This is a multi-layered sleight-of-hand. First, we had to ensure that no active/retire callbacks accidentally inverted the mutex ordering rules, nor assumed that they were themselves serialised by struct_mutex. More challenging though, is the rule over updating elements of the active rbtree. Instead of the whole i915_active now being serialised by struct_mutex, allocations/rotations of the tree are serialised by the i915_active.mutex and individual nodes are serialised by the caller using the i915_timeline.mutex (we need to use nested spinlocks to interact with the dma_fence callback lists). The pain point here is that instead of a single mutex around execbuf, we now have to take a mutex for active tracker (one for each vma, context, etc) and a couple of spinlocks for each fence update. The improvement in fine grained locking allowing for multiple concurrent clients (eventually!) should be worth it in typical loads. v2: Add some comments that barely elucidate anything :( Signed-off-by: Chris Wilson Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20191004134015.13204-6-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/display/intel_frontbuffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/i915/display/intel_frontbuffer.c') diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c index 6428b8dd70d3..84b164f31895 100644 --- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c +++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c @@ -257,7 +257,7 @@ intel_frontbuffer_get(struct drm_i915_gem_object *obj) front->obj = obj; kref_init(&front->ref); atomic_set(&front->bits, 0); - i915_active_init(i915, &front->write, + i915_active_init(&front->write, frontbuffer_active, i915_active_may_sleep(frontbuffer_retire)); -- cgit v1.2.3-59-g8ed1b