linux-kernel - [PATCH] drm/panfrost: Fix runtime PM imbalance in panfrost_perfcnt_enable

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Date:   Sun, 24 May 2020 10:18:46 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn, kjlu@....edu
Cc:     Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Steven Price <steven.price@....com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/panfrost: Fix runtime PM imbalance in panfrost_perfcnt_enable_locked

pm_runtime_get_sync() increments the runtime PM usage counter even
when it returns an error code. Thus a pairing decrement is needed on
the error handling path to keep the counter balanced. For all error
paths after pm_runtime_get_sync(), things are the same.

Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---
 drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
index 6913578d5aa7..d99bd2f0503a 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
@@ -83,11 +83,13 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 
 	ret = pm_runtime_get_sync(pfdev->dev);
 	if (ret < 0)
-		return ret;
+		goto err_pm_get;
 
 	bo = drm_gem_shmem_create(pfdev->ddev, perfcnt->bosize);
-	if (IS_ERR(bo))
-		return PTR_ERR(bo);
+	if (IS_ERR(bo)) {
+		ret = PTR_ERR(bo);
+		goto err_pm_get;
+	}
 
 	/* Map the perfcnt buf in the address space attached to file_priv. */
 	ret = panfrost_gem_open(&bo->base, file_priv);
@@ -168,6 +170,8 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 	panfrost_gem_close(&bo->base, file_priv);
 err_put_bo:
 	drm_gem_object_put_unlocked(&bo->base);
+err_pm_get:
+	pm_runtime_put_noidle(pfdev->dev);
 	return ret;
 }
 
-- 
2.17.1