[media] exynos4-is: Fix entity unregistration on error path

This patch corrects media entities unregistration order to make sure
the fimc.N.capture and fimc-lite video nodes are unregistered with
fimc->lock mutex held. This prevents races between video device open()
and defered probing and NULL pointer dereference in open() callback
as follows:
[   77.645000] Unable to handle kernel NULL pointer dereference at virtual address 00000290t
[   77.655000] pgd = ee7a8000
[   77.660000] [00000290] *pgd=6e13c831, *pte=00000000, *ppte=00000000
[   77.665000] Internal error: Oops: 17 [#1] PREEMPT SMP ARM
[   77.670000] Modules linked in: s5p_fimc ipv6 exynos_fimc_is exynos_fimc_lite
 s5p_csis v4l2_mem2mem videobuf2_dma_contig videobuf2_memops exynos4_is_common videobuf2_core [last unloaded: s5p_fimc]
[   77.685000] CPU: 0 PID : 2998 Comm: v4l_id Tainted: G        W   3.10.0-next-20130709-00039-g39f491b-dirty #1548
[   77.695000] task: ee084000 ti: ee46e000 task.ti: ee46e000
[   77.700000] PC is at __mutex_lock_slowpath+0x54/0x368
[   77.705000] LR is at __mutex_lock_slowpath+0x24/0x368
[   77.710000] pc : [<c038dc10>]    lr : [<c038dbe0>]    psr: 60000093
[   77.710000] sp : ee46fd70  ip : 000008c8  fp : c054e34c
[   77.725000] r10: ee084000  r9 : 00000000  r8 : ee439480
[   77.730000] r7 : ee46e000  r6 : 60000013  r5 : 00000290  r4 : 0000028c
[   77.735000] r3 : 00000000  r2 : 00000000  r1 : 20000093  r0 : 00000001
[   77.740000] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM Segment user
[   77.750000] Control: 10c5387d  Table: 6e7a804a  DAC: 00000015
[   77.755000] Process v4l_id (pid: 2998, stack limit = 0xee46e238)
[   77.760000] Stack: (0xee46fd70 to 0xee470000)
    	       ...
[   77.935000] [<c038dc10>] (__mutex_lock_slowpath+0x54/0x368) from [<c038df30>] (mutex_lock+0xc/0x24)
[   77.945000] [<c038df30>] (mutex_lock+0xc/0x24) from [<bf03fa90>] (fimc_lite_open+0x12c/0x2bc [exynos_fimc_lite])
[   77.955000] [<bf03fa90>] (fimc_lite_open+0x12c/0x2bc [exynos_fimc_lite]) from [<c02ab11c>] (v4l2_open+0xa0/0xe0)
[   77.965000] [<c02ab11c>] (v4l2_open+0xa0/0xe0) from [<c00b1de4>] (chrdev_open+0x88/0x170)
[   77.975000] [<c00b1de4>] (chrdev_open+0x88/0x170) from [<c00ac710>] (do_dentry_open.isra.14+0x1d8/0x258)
[   77.985000] [<c00ac710>] (do_dentry_open.isra.14+0x1d8/0x258) from [<c00ac860>] (finish_open+0x20/0x38)
[   77.995000] [<c00ac860>] (finish_open+0x20/0x38) from [<c00ba658>] (do_last.isra.43+0x538/0xb1c)
[   78.000000] [<c00ba658>] (do_last.isra.43+0x538/0xb1c) from [<c00bacf0>] (path_openat+0xb4/0x5c4)
[   78.010000] [<c00bacf0>] (path_openat+0xb4/0x5c4) from [<c00bb4b4>] (do_filp_open+0x2c/0x80)
[   78.020000] [<c00bb4b4>] (do_filp_open+0x2c/0x80) from [<c00ad744>] (do_sys_open+0xf4/0x1a8)
[   78.025000] [<c00ad744>] (do_sys_open+0xf4/0x1a8) from [<c000e320>] (ret_fast_syscall+0x0/0x30)
[   78.035000] Code: 1a000093 e10f6000 f10c0080 e2845004 (e1953f9f)

Reported-by: Andrzej Hajda <[email protected]>
Signed-off-by: Sylwester Nawrocki <[email protected]>
Signed-off-by: Kyungmin Park <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

drivers/media/platform/exynos4-is/media-dev.c

@@ -1530,9 +1530,9 @@ static int fimc_md_probe(struct platform_device *pdev)
 err_unlock:
 	mutex_unlock(&fmd->media_dev.graph_mutex);
 err_clk:
-	media_device_unregister(&fmd->media_dev);
 	fimc_md_put_clocks(fmd);
 	fimc_md_unregister_entities(fmd);
+	media_device_unregister(&fmd->media_dev);
 err_md:
 	v4l2_device_unregister(&fmd->v4l2_dev);
 	return ret;