linux-kernel - [PATCH] drm/vc4: fix ref count leak in vc4_dsi_encoder

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Message-Id: <20200614065251.94106-1-navid.emamdoost@gmail.com>
Date:   Sun, 14 Jun 2020 01:52:50 -0500
From:   Navid Emamdoost <navid.emamdoost@...il.com>
To:     Eric Anholt <eric@...olt.net>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     emamd001@....edu, wu000273@....edu, kjlu@....edu, smccaman@....edu,
        Navid Emamdoost <navid.emamdoost@...il.com>
Subject: [PATCH] drm/vc4: fix ref count leak in vc4_dsi_encoder_enable

in vc4_dsi_encoder_enable, the call to pm_runtime_get_sync increments
the counter even in case of failure, leading to incorrect
ref count. In case of failure, decrement the ref count before returning.

Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
---
 drivers/gpu/drm/vc4/vc4_dsi.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index eaf276978ee7..e651de9d1c7d 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -838,7 +838,7 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
 	ret = pm_runtime_get_sync(dev);
 	if (ret) {
 		DRM_ERROR("Failed to runtime PM enable on DSI%d\n", dsi->port);
-		return;
+		goto out;
 	}
 
 	if (debug_dump_regs) {
@@ -916,13 +916,13 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
 	ret = clk_prepare_enable(dsi->escape_clock);
 	if (ret) {
 		DRM_ERROR("Failed to turn on DSI escape clock: %d\n", ret);
-		return;
+		goto out;
 	}
 
 	ret = clk_prepare_enable(dsi->pll_phy_clock);
 	if (ret) {
 		DRM_ERROR("Failed to turn on DSI PLL: %d\n", ret);
-		return;
+		goto out;
 	}
 
 	hs_clock = clk_get_rate(dsi->pll_phy_clock);
@@ -944,7 +944,7 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
 	ret = clk_prepare_enable(dsi->pixel_clock);
 	if (ret) {
 		DRM_ERROR("Failed to turn on DSI pixel clock: %d\n", ret);
-		return;
+		goto out;
 	}
 
 	/* How many ns one DSI unit interval is.  Note that the clock
@@ -1088,6 +1088,8 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
 		dev_info(&dsi->pdev->dev, "DSI regs after:\n");
 		drm_print_regset32(&p, &dsi->regset);
 	}
+out:
+	pm_runtime_put(dev);
 }
 
 static ssize_t vc4_dsi_host_transfer(struct mipi_dsi_host *host,
-- 
2.17.1