linux-kernel - [PATCH drm-misc-next v2 5/9] drm/fsl-dcu: use drm_dev

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Message-Id: <20221001145802.515916-6-dakr@redhat.com>
Date:   Sat,  1 Oct 2022 16:57:58 +0200
From:   Danilo Krummrich <dakr@...hat.com>
To:     daniel@...ll.ch, airlied@...ux.ie, tzimmermann@...e.de,
        mripard@...nel.org, stefan@...er.ch, alison.wang@....com
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Danilo Krummrich <dakr@...hat.com>
Subject: [PATCH drm-misc-next v2 5/9] drm/fsl-dcu: use drm_dev_unplug()

When the driver is unbound, there might still be users in userspace
having an open fd and are calling into the driver.

While this is fine for drm managed resources, it is not for resources
bound to the device/driver lifecycle, e.g. clocks or MMIO mappings.

To prevent use-after-free issues we need to protect those resources with
drm_dev_enter() and drm_dev_exit(). This does only work if we indicate
that the drm device was unplugged, hence use drm_dev_unplug() instead of
drm_dev_unregister().

Protecting the particular resources with drm_dev_enter()/drm_dev_exit()
is handled by subsequent patches.

Signed-off-by: Danilo Krummrich <dakr@...hat.com>
---
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
index 4139f674c5de..3ac57516c3fe 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
@@ -340,7 +340,7 @@ static int fsl_dcu_drm_remove(struct platform_device *pdev)
 	struct fsl_dcu_drm_device *fsl_dev = platform_get_drvdata(pdev);
 	struct drm_device *drm = &fsl_dev->base;

-	drm_dev_unregister(drm);
+	drm_dev_unplug(drm);
 	clk_disable_unprepare(fsl_dev->clk);
 	clk_unregister(fsl_dev->pix_clk);

-- 
2.37.3