disp: msm: sde: fix potential race condition

Move the hist irq handling out of callback function, i.e., the hw
interrupt irq_lock context, to avoid dead lock between crtc spin_lock
and irq_lock. This change also extends crtc spin_lock coverage in
_sde_cp_crtc_enable_hist_irq to prevent null pointer dereference on
event node, which can be deleted during crtc event de-registration.

Change-Id: Iadaed54ab93c4c4abe065a8762d2addccb0c65c6
Signed-off-by: Ping Li <pingli@codeaurora.org>

msm/sde/sde_color_processing.c

@@ -1503,7 +1503,7 @@ static void _sde_cp_crtc_enable_hist_irq(struct sde_crtc *sde_crtc)
 	struct sde_hw_dspp *hw_dspp = NULL;
 	struct sde_crtc_irq_info *node = NULL;
 	int i, irq_idx, ret = 0;
-	unsigned long flags;
+	unsigned long flags, state_flags;
 
 	if (!crtc_drm) {
 		DRM_ERROR("invalid crtc %pK\n", crtc_drm);
@@ -1533,12 +1533,13 @@ static void _sde_cp_crtc_enable_hist_irq(struct sde_crtc *sde_crtc)
 
 	spin_lock_irqsave(&sde_crtc->spin_lock, flags);
 	node = _sde_cp_get_intr_node(DRM_EVENT_HISTOGRAM, sde_crtc);
-	spin_unlock_irqrestore(&sde_crtc->spin_lock, flags);
 
-	if (!node)
+	if (!node) {
+		spin_unlock_irqrestore(&sde_crtc->spin_lock, flags);
 		return;
+	}
 
-	spin_lock_irqsave(&node->state_lock, flags);
+	spin_lock_irqsave(&node->state_lock, state_flags);
 	if (node->state == IRQ_DISABLED) {
 		ret = sde_core_irq_enable(kms, &irq_idx, 1);
 		if (ret)
@@ -1546,7 +1547,8 @@ static void _sde_cp_crtc_enable_hist_irq(struct sde_crtc *sde_crtc)
 		else
 			node->state = IRQ_ENABLED;
 	}
-	spin_unlock_irqrestore(&node->state_lock, flags);
+	spin_unlock_irqrestore(&node->state_lock, state_flags);
+	spin_unlock_irqrestore(&sde_crtc->spin_lock, flags);
 }
 
 static int _sde_cp_crtc_checkfeature(u32 feature,
@@ -2543,6 +2545,7 @@ void sde_cp_crtc_destroy_properties(struct drm_crtc *crtc)
 	}
 	sde_crtc->ltm_buffer_cnt = 0;
 	sde_crtc->ltm_hist_en = false;
+	sde_crtc->hist_irq_idx = -1;
 
 	mutex_destroy(&sde_crtc->crtc_cp_lock);
 	INIT_LIST_HEAD(&sde_crtc->cp_active_list);
@@ -2685,6 +2688,7 @@ void sde_cp_crtc_clear(struct drm_crtc *crtc)
 	}
 	sde_crtc->ltm_buffer_cnt = 0;
 	sde_crtc->ltm_hist_en = false;
+	sde_crtc->hist_irq_idx = -1;
 	INIT_LIST_HEAD(&sde_crtc->ltm_buf_free);
 	INIT_LIST_HEAD(&sde_crtc->ltm_buf_busy);
 }
@@ -3519,45 +3523,20 @@ static void _sde_cp_hist_interrupt_cb(void *arg, int irq_idx)
 	struct sde_crtc *crtc = arg;
 	struct drm_crtc *crtc_drm = &crtc->base;
 	struct sde_hw_dspp *hw_dspp;
-	struct sde_kms *kms;
+	u32 lock_hist = 1;
-	struct sde_crtc_irq_info *node = NULL;
 	u32 i;
-	int ret = 0;
-	unsigned long flags;
-
-	/* disable histogram irq */
-	kms = get_kms(crtc_drm);
-	spin_lock_irqsave(&crtc->spin_lock, flags);
-	node = _sde_cp_get_intr_node(DRM_EVENT_HISTOGRAM, crtc);
-	spin_unlock_irqrestore(&crtc->spin_lock, flags);
-
-	if (!node) {
-		DRM_DEBUG_DRIVER("cannot find histogram event node in crtc\n");
-		return;
-	}
-
-	spin_lock_irqsave(&node->state_lock, flags);
-	if (node->state == IRQ_ENABLED) {
-		if (sde_core_irq_disable_nolock(kms, irq_idx)) {
-			DRM_ERROR("failed to disable irq %d, ret %d\n",
-				irq_idx, ret);
-			spin_unlock_irqrestore(&node->state_lock, flags);
-			return;
-		}
-		node->state = IRQ_DISABLED;
-	}
-	spin_unlock_irqrestore(&node->state_lock, flags);
 
 	/* lock histogram buffer */
 	for (i = 0; i < crtc->num_mixers; i++) {
 		hw_dspp = crtc->mixers[i].hw_dspp;
 		if (hw_dspp && hw_dspp->ops.lock_histogram)
-			hw_dspp->ops.lock_histogram(hw_dspp, NULL);
+			hw_dspp->ops.lock_histogram(hw_dspp, &lock_hist);
 	}
 
+	crtc->hist_irq_idx = irq_idx;
 	/* notify histogram event */
 	sde_crtc_event_queue(crtc_drm, _sde_cp_notify_hist_event,
-							NULL, true);
+						&crtc->hist_irq_idx, true);
 }
 
 static void _sde_cp_notify_hist_event(struct drm_crtc *crtc_drm, void *arg)
@@ -3567,11 +3546,13 @@ static void _sde_cp_notify_hist_event(struct drm_crtc *crtc_drm, void *arg)
 	struct drm_event event;
 	struct drm_msm_hist *hist_data;
 	struct sde_kms *kms;
-	int ret;
+	struct sde_crtc_irq_info *node = NULL;
-	u32 i;
+	unsigned long flags, state_flags;
+	int ret, irq_idx;
+	u32 i, lock_hist = 0;
 
-	if (!crtc_drm) {
+	if (!crtc_drm || !arg) {
-		DRM_ERROR("invalid crtc %pK\n", crtc_drm);
+		DRM_ERROR("invalid drm crtc %pK or arg %pK\n", crtc_drm, arg);
 		return;
 	}
 
@@ -3581,15 +3562,70 @@ static void _sde_cp_notify_hist_event(struct drm_crtc *crtc_drm, void *arg)
 		return;
 	}
 
-	if (!crtc->hist_blob)
-		return;
-
 	kms = get_kms(crtc_drm);
 	if (!kms || !kms->dev) {
 		SDE_ERROR("invalid arg(s)\n");
 		return;
 	}
 
+	/* disable histogram irq */
+	spin_lock_irqsave(&crtc->spin_lock, flags);
+	node = _sde_cp_get_intr_node(DRM_EVENT_HISTOGRAM, crtc);
+
+	if (!node) {
+		spin_unlock_irqrestore(&crtc->spin_lock, flags);
+		DRM_DEBUG_DRIVER("cannot find histogram event node in crtc\n");
+		/* unlock histogram */
+		ret = pm_runtime_get_sync(kms->dev->dev);
+		if (ret < 0) {
+			SDE_ERROR("failed to enable power resource %d\n", ret);
+			SDE_EVT32(ret, SDE_EVTLOG_ERROR);
+			return;
+		}
+		for (i = 0; i < crtc->num_mixers; i++) {
+			hw_dspp = crtc->mixers[i].hw_dspp;
+			if (hw_dspp && hw_dspp->ops.lock_histogram)
+				hw_dspp->ops.lock_histogram(hw_dspp,
+					&lock_hist);
+		}
+		pm_runtime_put_sync(kms->dev->dev);
+		return;
+	}
+
+	irq_idx = *(int *)arg;
+	spin_lock_irqsave(&node->state_lock, state_flags);
+	if (node->state == IRQ_ENABLED) {
+		ret = sde_core_irq_disable_nolock(kms, irq_idx);
+		if (ret) {
+			DRM_ERROR("failed to disable irq %d, ret %d\n",
+				irq_idx, ret);
+			spin_unlock_irqrestore(&node->state_lock, state_flags);
+			spin_unlock_irqrestore(&crtc->spin_lock, flags);
+			ret = pm_runtime_get_sync(kms->dev->dev);
+			if (ret < 0) {
+				SDE_ERROR("failed to enable power %d\n", ret);
+				SDE_EVT32(ret, SDE_EVTLOG_ERROR);
+				return;
+			}
+
+			/* unlock histogram */
+			for (i = 0; i < crtc->num_mixers; i++) {
+				hw_dspp = crtc->mixers[i].hw_dspp;
+				if (hw_dspp && hw_dspp->ops.lock_histogram)
+					hw_dspp->ops.lock_histogram(hw_dspp,
+						&lock_hist);
+			}
+			pm_runtime_put_sync(kms->dev->dev);
+			return;
+		}
+		node->state = IRQ_DISABLED;
+	}
+	spin_unlock_irqrestore(&node->state_lock, state_flags);
+	spin_unlock_irqrestore(&crtc->spin_lock, flags);
+
+	if (!crtc->hist_blob)
+		return;
+
 	ret = pm_runtime_get_sync(kms->dev->dev);
 	if (ret < 0) {
 		SDE_ERROR("failed to enable power resource %d\n", ret);

msm/sde/sde_crtc.h

@@ -290,6 +290,7 @@ struct sde_crtc_misr_info {
  * @ltm_buffer_lock : muttx to protect ltm_buffers allcation and free
  * @ltm_lock        : Spinlock to protect ltm buffer_cnt, hist_en and ltm lists
  * @needs_hw_reset  : Initiate a hw ctl reset
+ * @hist_irq_idx    : hist interrupt irq idx
  * @src_bpp         : source bpp used to calculate compression ratio
  * @target_bpp      : target bpp used to calculate compression ratio
  * @static_cache_read_work: delayed worker to transition cache state to read
@@ -383,6 +384,7 @@ struct sde_crtc {
 	struct mutex ltm_buffer_lock;
 	spinlock_t ltm_lock;
 	bool needs_hw_reset;
+	int hist_irq_idx;
 
 	int src_bpp;
 	int target_bpp;

msm/sde/sde_hw_color_processing_v1_7.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2016-2019, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2016-2019, 2021, The Linux Foundation. All rights reserved.
  */
 
 #include <drm/msm_drm_pp.h>
@@ -951,17 +951,17 @@ void sde_read_dspp_hist_v1_7(struct sde_hw_dspp *ctx, void *cfg)
 
 void sde_lock_dspp_hist_v1_7(struct sde_hw_dspp *ctx, void *cfg)
 {
-	u32 offset_ctl;
+	u32 offset_ctl, val;
 
-	if (!ctx) {
+	if (!ctx || !cfg) {
-		DRM_ERROR("invalid parameters ctx %pK", ctx);
+		DRM_ERROR("invalid parameters ctx %pK cfg %pK", ctx, cfg);
 		return;
 	}
 
 	offset_ctl = ctx->cap->sblk->hist.base + PA_HIST_CTRL_DSPP_OFF;
 
-	/* lock hist buffer */
+	val = (*(u32 *)cfg) & 0x1;
-	SDE_REG_WRITE(&ctx->hw, offset_ctl, 1);
+	SDE_REG_WRITE(&ctx->hw, offset_ctl, val);
 }
 
 void sde_setup_dspp_dither_v1_7(struct sde_hw_dspp *ctx, void *cfg)