linux-kernel - [PATCH 3.16 018/346] drm/nouveau: Don't leak runtime pm ref on driver unload

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Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Karol Herbst" <karolherbst@...il.com>,
        "Dave Airlie" <airlied@...hat.com>,
        "Lukas Wunner" <lukas@...ner.de>,
        "Daniel Vetter" <daniel.vetter@...ll.ch>,
        "Ben Skeggs" <bskeggs@...hat.com>, "Peter Wu" <peter@...ensteyn.nl>
Subject: [PATCH 3.16 018/346] drm/nouveau: Don't leak runtime pm ref on
 driver unload

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Lukas Wunner <lukas@...ner.de>

commit c1b16b45607976c76a3c41b8a319172b8b83f996 upstream.

nouveau_drm_load() calls pm_runtime_put() if nouveau_runtime_pm != 0,
but nouveau_drm_unload() calls pm_runtime_get_sync() unconditionally.
We therefore leak a runtime pm ref whenever nouveau is loaded with
runpm=0 and then unloaded. The GPU will subsequently never runtime
suspend even if nouveau is loaded again with runpm=1.

Fix by taking the runtime pm ref under the same condition that it was
released on driver load.

Fixes: 5addcf0a5f0f ("nouveau: add runtime PM support (v0.9)")
Cc: Dave Airlie <airlied@...hat.com>
Cc: Ben Skeggs <bskeggs@...hat.com>
Reported-by: Karol Herbst <karolherbst@...il.com>
Tested-by: Karol Herbst <karolherbst@...il.com>
Tested-by: Peter Wu <peter@...ensteyn.nl>
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1544b82007037601fbc510b1a50edc56c529e75f.1465392124.git.lukas@wunner.de
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/nouveau/nouveau_drm.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -472,7 +472,10 @@ nouveau_drm_unload(struct drm_device *de
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
 
-	pm_runtime_get_sync(dev->dev);
+	if (nouveau_runtime_pm != 0) {
+		pm_runtime_get_sync(dev->dev);
+	}
+
 	nouveau_fbcon_fini(dev);
 	nouveau_accel_fini(drm);
 	nouveau_hwmon_fini(dev);