From 5620b135aea49a8f41c86aaecfcb1598a7774121 Mon Sep 17 00:00:00 2001

From: Stephen Boyd <swboyd@chromium.org>

Date: Thu, 25 Mar 2021 14:28:22 -0700

Subject: [PATCH] drm/msm: Set drvdata to NULL when msm_drm_init() fails

Git-commit: 5620b135aea49a8f41c86aaecfcb1598a7774121

Patch-mainline: v5.12-rc7

References: git-fixes

We should set the platform device's driver data to NULL here so that

code doesn't assume the struct drm_device pointer is valid when it could

have been destroyed. The lifetime of this pointer is managed by a kref

but when msm_drm_init() fails we call drm_dev_put() on the pointer which

will free the pointer's memory. This driver uses the component model, so

there's sort of two "probes" in this file, one for the platform device

i.e. msm_pdev_probe() and one for the component i.e. msm_drm_bind(). The

msm_drm_bind() code is using the platform device's driver data to store

struct drm_device so the two functions are intertwined.

This relationship becomes a problem for msm_pdev_shutdown() when it

tests the NULL-ness of the pointer to see if it should call

drm_atomic_helper_shutdown(). The NULL test is a proxy check for if the

pointer has been freed by kref_put(). If the drm_device has been

destroyed, then we shouldn't call the shutdown helper, and we know that

is the case if msm_drm_init() failed, therefore set the driver data to

NULL so that this pointer liveness is tracked properly.

Fixes: 9d5cbf5fe46e ("drm/msm: add shutdown support for display platform_driver")

Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Cc: Fabio Estevam <festevam@gmail.com>

Cc: Krishna Manikandan <mkrishn@codeaurora.org>

Signed-off-by: Stephen Boyd <swboyd@chromium.org>

Message-id: <20210325212822.3663144-1-swboyd@chromium.org>

Signed-off-by: Rob Clark <robdclark@chromium.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/gpu/drm/msm/msm_drv.c | 1 +

 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c

index a5c6b8c23336..196907689c82 100644

--- a/drivers/gpu/drm/msm/msm_drv.c

+++ b/drivers/gpu/drm/msm/msm_drv.c

@@ -570,6 +570,7 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)

 	kfree(priv);

 err_put_drm_dev:

 	drm_dev_put(ddev);

+	platform_set_drvdata(pdev, NULL);

 	return ret;

 }

-- 

2.26.2