Re: [PATCH] drm/msm/dsi: Fix some reference counted resource leaks

From: Dmitry Baryshkov
Date: Fri Oct 01 2021 - 11:20:58 EST


On 06/08/2021 12:15, Christophe JAILLET wrote:
'of_find_device_by_node()' takes a reference that must be released when
not needed anymore.
This is expected to be done in 'dsi_destroy()'.

However, there are 2 issues in 'dsi_get_phy()'.

First, if 'of_find_device_by_node()' succeeds but 'platform_get_drvdata()'
returns NULL, 'msm_dsi->phy_dev' will still be NULL, and the reference
won't be released in 'dsi_destroy()'.

Secondly, as 'of_find_device_by_node()' already takes a reference, there is
no need for an additional 'get_device()'.

Move the assignment to 'msm_dsi->phy_dev' a few lines above and remove the
unneeded 'get_device()' to solve both issues.

Fixes: ec31abf6684e ("drm/msm/dsi: Separate PHY to another platform device")
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>

---
Review carefully, management of reference counted resources is sometimes
tricky.
---
drivers/gpu/drm/msm/dsi/dsi.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
index 75afc12a7b25..29d11f1cb79b 100644
--- a/drivers/gpu/drm/msm/dsi/dsi.c
+++ b/drivers/gpu/drm/msm/dsi/dsi.c
@@ -26,8 +26,10 @@ static int dsi_get_phy(struct msm_dsi *msm_dsi)
}
phy_pdev = of_find_device_by_node(phy_node);
- if (phy_pdev)
+ if (phy_pdev) {
msm_dsi->phy = platform_get_drvdata(phy_pdev);
+ msm_dsi->phy_dev = &phy_pdev->dev;
+ }
of_node_put(phy_node);
@@ -36,8 +38,6 @@ static int dsi_get_phy(struct msm_dsi *msm_dsi)
return -EPROBE_DEFER;
}
- msm_dsi->phy_dev = get_device(&phy_pdev->dev);
-
return 0;
}



--
With best wishes
Dmitry