media: exynos4-is: fix wrong mdev and v4l2 dev order in error path

When driver is built as module and probe during insmod is deferred
because of sensor subdevs, there is NULL pointer deference because
mdev is cleaned up and then access it from v4l2_device_unregister().
Fix the wrong mdev and v4l2 dev order in error path of probe.

This fixes below null pointer deference:
   Unable to handle kernel NULL pointer dereference at virtual address 00000000
   pgd = ca026f68
   [00000000] *pgd=00000000
   Internal error: Oops: 5 [#1] PREEMPT SMP ARM
   [...]
   Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
   PC is at ida_free+0x7c/0x160
   LR is at xas_start+0x44/0x204
   [...]
   [<c0dafd60>] (ida_free) from [<c083c20c>] (__media_device_unregister_entity+0x18/0xc0)
   [<c083c20c>] (__media_device_unregister_entity) from [<c083c2e0>] (media_device_unregister_entity+0x2c/0x38)
   [<c083c2e0>] (media_device_unregister_entity) from [<c0843404>] (v4l2_device_release+0xd0/0x104)
   [<c0843404>] (v4l2_device_release) from [<c0632558>] (device_release+0x28/0x98)
   [<c0632558>] (device_release) from [<c0db1204>] (kobject_put+0xa4/0x208)
   [<c0db1204>] (kct_put) from [<bf00bac4>] (fimc_capture_subdev_unregistered+0x58/0x6c [s5p_fimc])
   [<bf00bac4>] (fimc_capture_subdev_unregistered [s5p_fimc]) from [<c084a1cc>] (v4l2_device_unregister_subdev+0x6c/0xa8)
   [<c084a1cc>] (v4l2_device_unregister_subdev) from [<c084a350>] (v4l2_device_unregister+0x64/0x94)
   [<c084a350>] (v4l2_device_unregister) from [<bf0101ac>] (fimc_md_probe+0x4ec/0xaf8 [s5p_fimc])
   [...]

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Fixes: 9832e155f1ed ("[media] media-device: split media initialization and registration")
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

[sw0312.kim: cherry-pick mainline commit 4d741cbd58bf to handle exynos4-is issue]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>

Change-Id: Ib2f757574a180145d4972b861057f090a19d5f8f

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/media/platform/exynos4-is/media-dev.c b/drivers/media/platform/exynos4-is/media-dev.c
index d4656d5175d7..70a626cb47e9 100644
--- a/drivers/media/platform/exynos4-is/media-dev.c
+++ b/drivers/media/platform/exynos4-is/media-dev.c
@@ -1438,12 +1438,12 @@ static int fimc_md_probe(struct platform_device *pdev)
 	ret = v4l2_device_register(dev, &fmd->v4l2_dev);
 	if (ret < 0) {
 		v4l2_err(v4l2_dev, "Failed to register v4l2_device: %d\n", ret);
-		return ret;
+		goto err_md;
 	}
 
 	ret = fimc_md_get_clocks(fmd);
 	if (ret)
-		goto err_md;
+		goto err_v4l2dev;
 
 	ret = fimc_md_get_pinctrl(fmd);
 	if (ret < 0) {
@@ -1499,9 +1499,10 @@ err_clk:
 	fimc_md_put_clocks(fmd);
 err_m_ent:
 	fimc_md_unregister_entities(fmd);
+err_v4l2dev:
+	v4l2_device_unregister(&fmd->v4l2_dev);
 err_md:
 	media_device_cleanup(&fmd->media_dev);
-	v4l2_device_unregister(&fmd->v4l2_dev);
 	return ret;
 }