drm: hdlcd: Fix cleanup order

If hdlcd_drm_bind() fails at drm_fbdev_cma_init(), its cleanup will call
drm_mode_config_cleanup() as if to balance drm_mode_config_reset(). The
net result is that drm_connector_cleanup() will clean up the active
connectors long before component_unbind_all() gets called, so when the
connector later tries to clean up itself after being unbound, Bad Things
can happen:

[    4.121888] Unable to handle kernel NULL pointer dereference at
virtual address 00000000
[    4.129951] pgd = ffffff80091e0000
[    4.133345] [00000000] *pgd=00000009ffffe003, *pud=00000009ffffe003,
*pmd=0000000000000000
[    4.141613] Internal error: Oops: 96000005 [#1] PREEMPT SMP
[    4.147144] Modules linked in:
[    4.150188] CPU: 0 PID: 122 Comm: kworker/u12:2 Not tainted
4.8.0-rc2+ #989
[    4.157097] Hardware name: ARM Juno development board (r1) (DT)
[    4.162981] Workqueue: deferwq deferred_probe_work_func
[    4.168173] task: ffffffc975d93200 task.stack: ffffffc975dac000
[    4.174055] PC is at drm_connector_cleanup+0x58/0x1c0
[    4.179074] LR is at tda998x_unbind+0x24/0x40
[    4.183401] pc : [<ffffff80084c46f0>] lr : [<ffffff800850414c>]
pstate: 00000045
[    4.190750] sp : ffffffc975dafa10
[    4.194041] x29: ffffffc975dafa10 x28: ffffffc9768152a8
[    4.199325] x27: ffffffc97ff46450 x26: ffffff8008d99000
[    4.204608] x25: dead000000000100 x24: dead000000000200
[    4.209891] x23: ffffffc976bf91e8 x22: 0000000000000000
[    4.215172] x21: ffffffc976bf9170 x20: ffffffc976bf9170
[    4.220454] x19: ffffffc976bf9018 x18: 0000000000000000
[    4.225737] x17: 0000000074ce71ee x16: 000000008ff5d35f
[    4.231019] x15: ffffffc97681e91c x14: ffffffffffffffff
[    4.236301] x13: ffffffc97681e185 x12: 0000000000000038
[    4.241583] x11: 0101010101010101 x10: 0000000000000000
[    4.246866] x9 : 0000000040000000 x8 : 0000000000210d00
[    4.252148] x7 : ffffffc97fea8c00 x6 : 000000000000001b
[    4.257430] x5 : ffffff80084b7b8c x4 : 0000000000000080
[    4.262712] x3 : ffffff8008504128 x2 : ffffffc975df3800
[    4.267993] x1 : 0000000000000000 x0 : 0000000000000000
...
[    4.750937] [<ffffff80084c46f0>] drm_connector_cleanup+0x58/0x1c0
[    4.756990] [<ffffff800850414c>] tda998x_unbind+0x24/0x40
[    4.762354] [<ffffff8008507918>] component_unbind.isra.4+0x28/0x50
[    4.768492] [<ffffff8008507a0c>] component_unbind_all+0xcc/0xd8
[    4.774373] [<ffffff80084d5adc>] hdlcd_drm_bind+0x234/0x418
[    4.779909] [<ffffff8008507b58>] try_to_bring_up_master+0x140/0x1a0
[    4.786133] [<ffffff8008507c50>] component_add+0x98/0x170
[    4.791496] [<ffffff8008504b90>] tda998x_probe+0x18/0x20
[    4.796774] [<ffffff80086bf914>] i2c_device_probe+0x164/0x258
[    4.802481] [<ffffff800850d094>] driver_probe_device+0x204/0x2b0
[    4.808447] [<ffffff800850d28c>] __device_attach_driver+0x9c/0xf8
[    4.814498] [<ffffff800850b108>] bus_for_each_drv+0x58/0x98
[    4.820033] [<ffffff800850cd64>] __device_attach+0xc4/0x138
[    4.825567] [<ffffff800850d338>] device_initial_probe+0x10/0x18
[    4.831446] [<ffffff800850c124>] bus_probe_device+0x94/0xa0
[    4.836981] [<ffffff800850c5b0>] deferred_probe_work_func+0x78/0xb0
[    4.843207] [<ffffff80080d2998>] process_one_work+0x118/0x378
[    4.848914] [<ffffff80080d2c40>] worker_thread+0x48/0x498
[    4.854276] [<ffffff80080d8918>] kthread+0xd0/0xe8
[    4.859036] [<ffffff8008082e90>] ret_from_fork+0x10/0x40
[    4.864314] Code: f2fbd5b9 f2fbd5b8 f8478ee0 eb17001f (f9400013)
[    4.870472] ---[ end trace a643cfe4ce1d838b ]---

Fix this by moving the drm_mode_config_cleanup() much later such that it
correctly balances drm_mode_config_init().

Suggested-by: Russell King <linux@armlinux.org.uk>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c b/drivers/gpu/drm/arm/hdlcd_drv.c
index fb6a418ce6be611176e26bf5fa699503178e8364..e138fb51e8ce58e1ac6bad38c96447e68152ec48 100644 (file)
--- a/drivers/gpu/drm/arm/hdlcd_drv.c
+++ b/drivers/gpu/drm/arm/hdlcd_drv.c
@@ -375,7 +375,6 @@ static int hdlcd_drm_bind(struct device *dev)
 
 err_fbdev:
        drm_kms_helper_poll_fini(drm);
-       drm_mode_config_cleanup(drm);
        drm_vblank_cleanup(drm);
 err_vblank:
        pm_runtime_disable(drm->dev);
@@ -387,6 +386,7 @@ err_unload:
        drm_irq_uninstall(drm);
        of_reserved_mem_device_release(drm->dev);
 err_free:
+       drm_mode_config_cleanup(drm);
        dev_set_drvdata(dev, NULL);
        drm_dev_unref(drm);