linux-kernel - [PATCH 5.1 397/405] drm/drv: Hold ref on parent device during drm

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Date:   Wed, 29 May 2019 20:06:35 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Noralf Trønnes <noralf@...nnes.org>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 397/405] drm/drv: Hold ref on parent device during drm_device lifetime

[ Upstream commit 56be6503aab2bc3a30beae408071b9be5e1bae51 ]

This makes it safe to access drm_device->dev after the parent device has
been removed/unplugged.

Signed-off-by: Noralf Trønnes <noralf@...nnes.org>
Reviewed-by: Gerd Hoffmann <kraxel@...hat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190225144232.20761-2-noralf@tronnes.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/drm_drv.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 05bbc2b622fc1..04aa6ccdfb242 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -497,7 +497,7 @@ int drm_dev_init(struct drm_device *dev,
 	BUG_ON(!parent);
 
 	kref_init(&dev->ref);
-	dev->dev = parent;
+	dev->dev = get_device(parent);
 	dev->driver = driver;
 
 	/* no per-device feature limits by default */
@@ -567,6 +567,7 @@ int drm_dev_init(struct drm_device *dev,
 	drm_minor_free(dev, DRM_MINOR_RENDER);
 	drm_fs_inode_free(dev->anon_inode);
 err_free:
+	put_device(dev->dev);
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->ctxlist_mutex);
 	mutex_destroy(&dev->clientlist_mutex);
@@ -602,6 +603,8 @@ void drm_dev_fini(struct drm_device *dev)
 	drm_minor_free(dev, DRM_MINOR_PRIMARY);
 	drm_minor_free(dev, DRM_MINOR_RENDER);
 
+	put_device(dev->dev);
+
 	mutex_destroy(&dev->master_mutex);
 	mutex_destroy(&dev->ctxlist_mutex);
 	mutex_destroy(&dev->clientlist_mutex);
-- 
2.20.1