linux-kernel - [PATCH -next] gpu: drm: Fix spinlock vblank_time

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Date:   Wed, 22 Jul 2020 01:05:27 +0000
From:   Xu Qiang <xuqiang36@...wei.com>
To:     <maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <airlied@...ux.ie>, <daniel@...ll.ch>
CC:     <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <rui.xiang@...wei.com>
Subject: [PATCH -next] gpu: drm: Fix spinlock vblank_time_lock use error.

The drm_handle_vblank function is in the interrupt context.
Therefore, the spin lock vblank_time_lock is obtained
from the interrupt context.

Cc: <stable@...r.kernel.org>
Signed-off-by: Xu Qiang <xuqiang36@...wei.com>
---
 drivers/gpu/drm/drm_vblank.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index f402c75b9d34..4ca63ff33a43 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -229,10 +229,11 @@ static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe
 {
 	u32 cur_vblank;
 	bool rc;
+	unsigned long irqflags;
 	ktime_t t_vblank;
 	int count = DRM_TIMESTAMP_MAXRETRIES;
 
-	spin_lock(&dev->vblank_time_lock);
+	spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
 
 	/*
 	 * sample the current counter to avoid random jumps
@@ -257,7 +258,7 @@ static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe
 	 */
 	store_vblank(dev, pipe, 1, t_vblank, cur_vblank);
 
-	spin_unlock(&dev->vblank_time_lock);
+	spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
 }
 
 /*
@@ -1106,11 +1107,12 @@ static int __enable_vblank(struct drm_device *dev, unsigned int pipe)
 static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe)
 {
 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+	unsigned long irqflags;
 	int ret = 0;
 
 	assert_spin_locked(&dev->vbl_lock);
 
-	spin_lock(&dev->vblank_time_lock);
+	spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
 
 	if (!vblank->enabled) {
 		/*
@@ -1136,7 +1138,7 @@ static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe)
 		}
 	}
 
-	spin_unlock(&dev->vblank_time_lock);
+	spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
 
 	return ret;
 }
@@ -1917,6 +1919,7 @@ bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
 {
 	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
 	unsigned long irqflags;
+	unsigned long irqflags_vblank;
 	bool disable_irq;
 
 	if (drm_WARN_ON_ONCE(dev, !drm_dev_has_vblank(dev)))
@@ -1931,18 +1934,18 @@ bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
 	 * vblank enable/disable, as this would cause inconsistent
 	 * or corrupted timestamps and vblank counts.
 	 */
-	spin_lock(&dev->vblank_time_lock);
+	spin_lock_irqsave(&dev->vblank_time_lock, irqflags_vblank);
 
 	/* Vblank irq handling disabled. Nothing to do. */
 	if (!vblank->enabled) {
-		spin_unlock(&dev->vblank_time_lock);
+		spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags_vblank);
 		spin_unlock_irqrestore(&dev->event_lock, irqflags);
 		return false;
 	}
 
 	drm_update_vblank_count(dev, pipe, true);
 
-	spin_unlock(&dev->vblank_time_lock);
+	spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags_vblank);
 
 	wake_up(&vblank->queue);
 
-- 
2.25.0