drm/i915: Move atomic state free from out of fence release

Fences are required to support being released from under an atomic context. The drm_atomic_state struct may take a mutex when being released and so we cannot drop a reference to the drm_atomic_state from the fence release path directly, and so we need to defer that unreference to a worker. [ 326.576697] WARNING: CPU: 2 PID: 366 at kernel/sched/core.c:7737 __might_sleep+0x5d/0x80 [ 326.576816] do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffffc0359549>] intel_breadcrumbs_signaler+0x59/0x270 [i915] [ 326.576818] Modules linked in: rfcomm fuse snd_hda_codec_hdmi bnep snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer input_leds led_class snd punit_atom_debug btusb btrtl btbcm btintel intel_rapl bluetooth i915 drm_kms_helper syscopyarea sysfillrect iwlwifi sysimgblt soundcore fb_sys_fops mei_txe cfg80211 drm pwm_lpss_platform pwm_lpss pinctrl_cherryview fjes acpi_pad parport_pc ppdev parport autofs4 [ 326.576899] CPU: 2 PID: 366 Comm: i915/signal:0 Tainted: G U 4.10.0-rc3-patser+ #5030 [ 326.576902] Hardware name: /NUC5PPYB, BIOS PYBSWCEL.86A.0031.2015.0601.1712 06/01/2015 [ 326.576905] Call Trace: [ 326.576920] dump_stack+0x4d/0x6d [ 326.576926] __warn+0xc0/0xe0 [ 326.576931] warn_slowpath_fmt+0x5a/0x80 [ 326.577004] ? intel_breadcrumbs_signaler+0x59/0x270 [i915] [ 326.577075] ? intel_breadcrumbs_signaler+0x59/0x270 [i915] [ 326.577079] __might_sleep+0x5d/0x80 [ 326.577087] mutex_lock+0x1b/0x40 [ 326.577133] drm_property_free_blob+0x1e/0x80 [drm] [ 326.577167] ? drm_property_destroy+0xe0/0xe0 [drm] [ 326.577200] drm_mode_object_unreference+0x5c/0x70 [drm] [ 326.577233] drm_property_unreference_blob+0xe/0x10 [drm] [ 326.577260] __drm_atomic_helper_crtc_destroy_state+0x14/0x40 [drm_kms_helper] [ 326.577278] drm_atomic_helper_crtc_destroy_state+0x10/0x20 [drm_kms_helper] [ 326.577352] intel_crtc_destroy_state+0x9/0x10 [i915] [ 326.577388] drm_atomic_state_default_clear+0xea/0x1d0 [drm] [ 326.577462] intel_atomic_state_clear+0xd/0x20 [i915] [ 326.577497] drm_atomic_state_clear+0x1a/0x30 [drm] [ 326.577532] __drm_atomic_state_free+0x13/0x60 [drm] [ 326.577607] intel_atomic_commit_ready+0x6f/0x78 [i915] [ 326.577670] i915_sw_fence_release+0x3a/0x50 [i915] [ 326.577733] dma_i915_sw_fence_wake+0x39/0x80 [i915] [ 326.577741] dma_fence_signal+0xda/0x120 [ 326.577812] ? intel_breadcrumbs_signaler+0x59/0x270 [i915] [ 326.577884] intel_breadcrumbs_signaler+0xb1/0x270 [i915] [ 326.577889] kthread+0x127/0x130 [ 326.577961] ? intel_engine_remove_wait+0x1a0/0x1a0 [i915] [ 326.577964] ? kthread_stop+0x120/0x120 [ 326.577970] ret_from_fork+0x22/0x30 Fixes: c004a90 ("drm/i915: Restore nonblocking awaits for modesetting") Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20170123212939.30345-1-chris@chris-wilson.co.uk Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.10-rc1+ Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> (cherry picked from commit eb955ee) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
mariux64 · Jan 25, 2017 · 6f0f02d · 6f0f02d
1 parent 6d1d427
commit 6f0f02d
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Showing 3 changed files with 33 additions and 2 deletions.
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
@@ -1977,6 +1977,11 @@ struct drm_i915_private {
 
 	struct i915_frontbuffer_tracking fb_tracking;
 
+	struct intel_atomic_helper {
+		struct llist_head free_list;
+		struct work_struct free_work;
+	} atomic_helper;
+
 	u16 orig_clock;
 
 	bool mchbar_need_disable;

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
@@ -14523,8 +14523,14 @@ intel_atomic_commit_ready(struct i915_sw_fence *fence,
 		break;
 
 	case FENCE_FREE:
-		drm_atomic_state_put(&state->base);
-		break;
+		{
+			struct intel_atomic_helper *helper =
+				&to_i915(state->base.dev)->atomic_helper;
+
+			if (llist_add(&state->freed, &helper->free_list))
+				schedule_work(&helper->free_work);
+			break;
+		}
 	}
 
 	return NOTIFY_DONE;
@@ -16403,6 +16409,18 @@ static void sanitize_watermarks(struct drm_device *dev)
 	drm_modeset_acquire_fini(&ctx);
 }
 
+static void intel_atomic_helper_free_state(struct work_struct *work)
+{
+	struct drm_i915_private *dev_priv =
+		container_of(work, typeof(*dev_priv), atomic_helper.free_work);
+	struct intel_atomic_state *state, *next;
+	struct llist_node *freed;
+
+	freed = llist_del_all(&dev_priv->atomic_helper.free_list);
+	llist_for_each_entry_safe(state, next, freed, freed)
+		drm_atomic_state_put(&state->base);
+}
+
 int intel_modeset_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
@@ -16422,6 +16440,9 @@ int intel_modeset_init(struct drm_device *dev)
 
 	dev->mode_config.funcs = &intel_mode_funcs;
 
+	INIT_WORK(&dev_priv->atomic_helper.free_work,
+		  intel_atomic_helper_free_state);
+
 	intel_init_quirks(dev);
 
 	intel_init_pm(dev_priv);
@@ -17106,6 +17127,9 @@ void intel_modeset_cleanup(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
+	flush_work(&dev_priv->atomic_helper.free_work);
+	WARN_ON(!llist_empty(&dev_priv->atomic_helper.free_list));
+
 	intel_disable_gt_powersave(dev_priv);
 
 	/*

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
@@ -370,6 +370,8 @@ struct intel_atomic_state {
 	struct skl_wm_values wm_results;
 
 	struct i915_sw_fence commit_ready;
+
+	struct llist_node freed;
 };
 
 struct intel_plane_state {