[PATCH AUTOSEL 5.16 19/52] drm/vc4: Fix deadlock on DSI device attach error

Sasha Levin
2022-02-03T20:32:44Z

From: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>

[ Upstream commit 0a3d12ab5097b1d045e693412e6b366b7e82031b ]

DSI device attach to DSI host will be done with host device's lock
held.

Un-registering host in "device attach" error path (ex: probe retry)
will result in deadlock with below call trace and non operational
DSI display.

Startup Call trace:
[ 35.043036] rt_mutex_slowlock.constprop.21+0x184/0x1b8
[ 35.043048] mutex_lock_nested+0x7c/0xc8
[ 35.043060] device_del+0x4c/0x3e8
[ 35.043075] device_unregister+0x20/0x40
[ 35.043082] mipi_dsi_remove_device_fn+0x18/0x28
[ 35.043093] device_for_each_child+0x68/0xb0
[ 35.043105] mipi_dsi_host_unregister+0x40/0x90
[ 35.043115] vc4_dsi_host_attach+0xf0/0x120 [vc4]
[ 35.043199] mipi_dsi_attach+0x30/0x48
[ 35.043209] tc358762_probe+0x128/0x164 [tc358762]
[ 35.043225] mipi_dsi_drv_probe+0x28/0x38
[ 35.043234] really_probe+0xc0/0x318
[ 35.043244] __driver_probe_device+0x80/0xe8
[ 35.043254] driver_probe_device+0xb8/0x118
[ 35.043263] __device_attach_driver+0x98/0xe8
[ 35.043273] bus_for_each_drv+0x84/0xd8
[ 35.043281] __device_attach+0xf0/0x150
[ 35.043290] device_initial_probe+0x1c/0x28
[ 35.043300] bus_probe_device+0xa4/0xb0
[ 35.043308] deferred_probe_work_func+0xa0/0xe0
[ 35.043318] process_one_work+0x254/0x700
[ 35.043330] worker_thread+0x4c/0x448
[ 35.043339] kthread+0x19c/0x1a8
[ 35.043348] ret_from_fork+0x10/0x20

Shutdown Call trace:
[ 365.565417] Call trace:
[ 365.565423] __switch_to+0x148/0x200
[ 365.565452] __schedule+0x340/0x9c8
[ 365.565467] schedule+0x48/0x110
[ 365.565479] schedule_timeout+0x3b0/0x448
[ 365.565496] wait_for_completion+0xac/0x138
[ 365.565509] __flush_work+0x218/0x4e0
[ 365.565523] flush_work+0x1c/0x28
[ 365.565536] wait_for_device_probe+0x68/0x158
[ 365.565550] device_shutdown+0x24/0x348
[ 365.565561] kernel_restart_prepare+0x40/0x50
[ 365.565578] kernel_restart+0x20/0x70
[ 365.565591] __do_sys_reboot+0x10c/0x220
[ 365.565605] __arm64_sys_reboot+0x2c/0x38
[ 365.565619] invoke_syscall+0x4c/0x110
[ 365.565634] el0_svc_common.constprop.3+0xfc/0x120
[ 365.565648] do_el0_svc+0x2c/0x90
[ 365.565661] el0_svc+0x4c/0xf0
[ 365.565671] el0t_64_sync_handler+0x90/0xb8
[ 365.565682] el0t_64_sync+0x180/0x184

Signed-off-by: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220118005127.29015-1-treasure4paddy@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/vc4/vc4_dsi.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index a229da58962a2..9300d3354c512 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -1262,7 +1262,6 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
struct mipi_dsi_device *device)
{
struct vc4_dsi *dsi = host_to_dsi(host);
- int ret;

dsi->lanes = device->lanes;
dsi->channel = device->channel;
@@ -1297,18 +1296,15 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host,
return 0;
}

- ret = component_add(&dsi->pdev->dev, &vc4_dsi_ops);
- if (ret) {
- mipi_dsi_host_unregister(&dsi->dsi_host);
- return ret;
- }
-
- return 0;
+ return component_add(&dsi->pdev->dev, &vc4_dsi_ops);
}

static int vc4_dsi_host_detach(struct mipi_dsi_host *host,
struct mipi_dsi_device *device)
{
+ struct vc4_dsi *dsi = host_to_dsi(host);
+
+ component_del(&dsi->pdev->dev, &vc4_dsi_ops);
return 0;
}

@@ -1686,9 +1682,7 @@ static int vc4_dsi_dev_remove(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct vc4_dsi *dsi = dev_get_drvdata(dev);

- component_del(&pdev->dev, &vc4_dsi_ops);
mipi_dsi_host_unregister(&dsi->dsi_host);
-
return 0;
}

--
2.34.1