From da42104f589d979bbe402703fd836cec60befae1 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 18 Dec 2019 10:40:43 +0000 Subject: drm/i915: Hold reference to intel_frontbuffer as we track activity Since obj->frontbuffer is no longer protected by the struct_mutex, as we are processing the execbuf, it may be removed. Mark the intel_frontbuffer as rcu protected, and so acquire a reference to the struct as we track activity upon it. Closes: https://gitlab.freedesktop.org/drm/intel/issues/827 Fixes: 8e7cb1799b4f ("drm/i915: Extract intel_frontbuffer active tracking") Signed-off-by: Chris Wilson Cc: Matthew Auld Cc: # v5.4+ Reviewed-by: Joonas Lahtinen Link: https://patchwork.freedesktop.org/patch/msgid/20191218104043.3539458-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/display/intel_frontbuffer.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) (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 84b164f31895..6cb02c912acc 100644 --- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c +++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c @@ -229,11 +229,11 @@ static void frontbuffer_release(struct kref *ref) vma->display_alignment = I915_GTT_MIN_ALIGNMENT; spin_unlock(&obj->vma.lock); - obj->frontbuffer = NULL; + RCU_INIT_POINTER(obj->frontbuffer, NULL); spin_unlock(&to_i915(obj->base.dev)->fb_tracking.lock); i915_gem_object_put(obj); - kfree(front); + kfree_rcu(front, rcu); } struct intel_frontbuffer * @@ -242,11 +242,7 @@ intel_frontbuffer_get(struct drm_i915_gem_object *obj) struct drm_i915_private *i915 = to_i915(obj->base.dev); struct intel_frontbuffer *front; - spin_lock(&i915->fb_tracking.lock); - front = obj->frontbuffer; - if (front) - kref_get(&front->ref); - spin_unlock(&i915->fb_tracking.lock); + front = __intel_frontbuffer_get(obj); if (front) return front; @@ -262,13 +258,13 @@ intel_frontbuffer_get(struct drm_i915_gem_object *obj) i915_active_may_sleep(frontbuffer_retire)); spin_lock(&i915->fb_tracking.lock); - if (obj->frontbuffer) { + if (rcu_access_pointer(obj->frontbuffer)) { kfree(front); - front = obj->frontbuffer; + front = rcu_dereference_protected(obj->frontbuffer, true); kref_get(&front->ref); } else { i915_gem_object_get(obj); - obj->frontbuffer = front; + rcu_assign_pointer(obj->frontbuffer, front); } spin_unlock(&i915->fb_tracking.lock); -- cgit v1.2.3