[PATCH AUTOSEL 5.4 1/6] drm/komeda: drop all currently held locks if deadlock happens

From: Sasha Levin
Date: Tue Nov 07 2023 - 07:45:23 EST

From: "baozhu.liu" <lucas.liu@xxxxxxxxxxxx>

[ Upstream commit 19ecbe8325a2a7ffda5ff4790955b84eaccba49f ]

If komeda_pipeline_unbound_components() returns -EDEADLK,
it means that a deadlock happened in the locking context.
Currently, komeda is not dealing with the deadlock properly,producing the
following output when CONFIG_DEBUG_WW_MUTEX_SLOWPATH is enabled:

------------[ cut here ]------------
[ 26.103984] WARNING: CPU: 2 PID: 345 at drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c:1248
komeda_release_unclaimed_resources+0x13c/0x170
[ 26.117453] Modules linked in:
[ 26.120511] CPU: 2 PID: 345 Comm: composer@2.1-se Kdump: loaded Tainted: G W 5.10.110-SE-SDK1.8-dirty #16
[ 26.131374] Hardware name: Siengine Se1000 Evaluation board (DT)
[ 26.137379] pstate: 20400009 (nzCv daif +PAN -UAO -TCO BTYPE=--)
[ 26.143385] pc : komeda_release_unclaimed_resources+0x13c/0x170
[ 26.149301] lr : komeda_release_unclaimed_resources+0xbc/0x170
[ 26.155130] sp : ffff800017b8b8d0
[ 26.158442] pmr_save: 000000e0
[ 26.161493] x29: ffff800017b8b8d0 x28: ffff000cf2f96200
[ 26.166805] x27: ffff000c8f5a8800 x26: 0000000000000000
[ 26.172116] x25: 0000000000000038 x24: ffff8000116a0140
[ 26.177428] x23: 0000000000000038 x22: ffff000cf2f96200
[ 26.182739] x21: ffff000cfc300300 x20: ffff000c8ab77080
[ 26.188051] x19: 0000000000000003 x18: 0000000000000000
[ 26.193362] x17: 0000000000000000 x16: 0000000000000000
[ 26.198672] x15: b400e638f738ba38 x14: 0000000000000000
[ 26.203983] x13: 0000000106400a00 x12: 0000000000000000
[ 26.209294] x11: 0000000000000000 x10: 0000000000000000
[ 26.214604] x9 : ffff800012f80000 x8 : ffff000ca3308000
[ 26.219915] x7 : 0000000ff3000000 x6 : ffff80001084034c
[ 26.225226] x5 : ffff800017b8bc40 x4 : 000000000000000f
[ 26.230536] x3 : ffff000ca3308000 x2 : 0000000000000000
[ 26.235847] x1 : 0000000000000000 x0 : ffffffffffffffdd
[ 26.241158] Call trace:
[ 26.243604] komeda_release_unclaimed_resources+0x13c/0x170
[ 26.249175] komeda_crtc_atomic_check+0x68/0xf0
[ 26.253706] drm_atomic_helper_check_planes+0x138/0x1f4
[ 26.258929] komeda_kms_check+0x284/0x36c
[ 26.262939] drm_atomic_check_only+0x40c/0x714
[ 26.267381] drm_atomic_nonblocking_commit+0x1c/0x60
[ 26.272344] drm_mode_atomic_ioctl+0xa3c/0xb8c
[ 26.276787] drm_ioctl_kernel+0xc4/0x120
[ 26.280708] drm_ioctl+0x268/0x534
[ 26.284109] __arm64_sys_ioctl+0xa8/0xf0
[ 26.288030] el0_svc_common.constprop.0+0x80/0x240
[ 26.292817] do_el0_svc+0x24/0x90
[ 26.296132] el0_svc+0x20/0x30
[ 26.299185] el0_sync_handler+0xe8/0xf0
[ 26.303018] el0_sync+0x1a4/0x1c0
[ 26.306330] irq event stamp: 0
[ 26.309384] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[ 26.315650] hardirqs last disabled at (0): [<ffff800010056d34>] copy_process+0x5d0/0x183c
[ 26.323825] softirqs last enabled at (0): [<ffff800010056d34>] copy_process+0x5d0/0x183c
[ 26.331997] softirqs last disabled at (0): [<0000000000000000>] 0x0
[ 26.338261] ---[ end trace 20ae984fa860184a ]---
[ 26.343021] ------------[ cut here ]------------
[ 26.347646] WARNING: CPU: 3 PID: 345 at drivers/gpu/drm/drm_modeset_lock.c:228 drm_modeset_drop_locks+0x84/0x90
[ 26.357727] Modules linked in:
[ 26.360783] CPU: 3 PID: 345 Comm: composer@2.1-se Kdump: loaded Tainted: G W 5.10.110-SE-SDK1.8-dirty #16
[ 26.371645] Hardware name: Siengine Se1000 Evaluation board (DT)
[ 26.377647] pstate: 20400009 (nzCv daif +PAN -UAO -TCO BTYPE=--)
[ 26.383649] pc : drm_modeset_drop_locks+0x84/0x90
[ 26.388351] lr : drm_mode_atomic_ioctl+0x860/0xb8c
[ 26.393137] sp : ffff800017b8bb10
[ 26.396447] pmr_save: 000000e0
[ 26.399497] x29: ffff800017b8bb10 x28: 0000000000000001
[ 26.404807] x27: 0000000000000038 x26: 0000000000000002
[ 26.410115] x25: ffff000cecbefa00 x24: ffff000cf2f96200
[ 26.415423] x23: 0000000000000001 x22: 0000000000000018
[ 26.420731] x21: 0000000000000001 x20: ffff800017b8bc10
[ 26.426039] x19: 0000000000000000 x18: 0000000000000000
[ 26.431347] x17: 0000000002e8bf2c x16: 0000000002e94c6b
[ 26.436655] x15: 0000000002ea48b9 x14: ffff8000121f0300
[ 26.441963] x13: 0000000002ee2ca8 x12: ffff80001129cae0
[ 26.447272] x11: ffff800012435000 x10: ffff000ed46b5e88
[ 26.452580] x9 : ffff000c9935e600 x8 : 0000000000000000
[ 26.457888] x7 : 000000008020001e x6 : 000000008020001f
[ 26.463196] x5 : ffff80001085fbe0 x4 : fffffe0033a59f20
[ 26.468504] x3 : 000000008020001e x2 : 0000000000000000
[ 26.473813] x1 : 0000000000000000 x0 : ffff000c8f596090
[ 26.479122] Call trace:
[ 26.481566] drm_modeset_drop_locks+0x84/0x90
[ 26.485918] drm_mode_atomic_ioctl+0x860/0xb8c
[ 26.490359] drm_ioctl_kernel+0xc4/0x120
[ 26.494278] drm_ioctl+0x268/0x534
[ 26.497677] __arm64_sys_ioctl+0xa8/0xf0
[ 26.501598] el0_svc_common.constprop.0+0x80/0x240
[ 26.506384] do_el0_svc+0x24/0x90
[ 26.509697] el0_svc+0x20/0x30
[ 26.512748] el0_sync_handler+0xe8/0xf0
[ 26.516580] el0_sync+0x1a4/0x1c0
[ 26.519891] irq event stamp: 0
[ 26.522943] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[ 26.529207] hardirqs last disabled at (0): [<ffff800010056d34>] copy_process+0x5d0/0x183c
[ 26.537379] softirqs last enabled at (0): [<ffff800010056d34>] copy_process+0x5d0/0x183c
[ 26.545550] softirqs last disabled at (0): [<0000000000000000>] 0x0
[ 26.551812] ---[ end trace 20ae984fa860184b ]---

According to the call trace information,it can be located to be
WARN_ON(IS_ERR(c_st)) in the komeda_pipeline_unbound_components function;
Then follow the function.
komeda_pipeline_unbound_components
-> komeda_component_get_state_and_set_user
-> komeda_pipeline_get_state_and_set_crtc
-> komeda_pipeline_get_state
->drm_atomic_get_private_obj_state
-> drm_atomic_get_private_obj_state
-> drm_modeset_lock

komeda_pipeline_unbound_components
-> komeda_component_get_state_and_set_user
-> komeda_component_get_state
-> drm_atomic_get_private_obj_state
-> drm_modeset_lock

ret = drm_modeset_lock(&obj->lock, state->acquire_ctx); if (ret)
return ERR_PTR(ret);
Here it return -EDEADLK.

deal with the deadlock as suggested by [1], using the
function drm_modeset_backoff().
[1] https://docs.kernel.org/gpu/drm-kms.html?highlight=kms#kms-locking

Therefore, handling this problem can be solved
by adding return -EDEADLK back to the drm_modeset_backoff processing flow
in the drm_mode_atomic_ioctl function.

Signed-off-by: baozhu.liu <lucas.liu@xxxxxxxxxxxx>
Signed-off-by: menghui.huang <menghui.huang@xxxxxxxxxxxx>
Reviewed-by: Liviu Dudau <liviu.dudau@xxxxxxx>
Signed-off-by: Liviu Dudau <liviu.dudau@xxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230804013117.6870-1-menghui.huang@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
.../gpu/drm/arm/display/komeda/komeda_pipeline_state.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
index b848270e0a1f4..31527fb66b5c5 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_pipeline_state.c
@@ -1171,7 +1171,7 @@ int komeda_build_display_data_flow(struct komeda_crtc *kcrtc,
return 0;
}

-static void
+static int
komeda_pipeline_unbound_components(struct komeda_pipeline *pipe,
struct komeda_pipeline_state *new)
{
@@ -1190,8 +1190,12 @@ komeda_pipeline_unbound_components(struct komeda_pipeline *pipe,
c = komeda_pipeline_get_component(pipe, id);
c_st = komeda_component_get_state_and_set_user(c,
drm_st, NULL, new->crtc);
+ if (PTR_ERR(c_st) == -EDEADLK)
+ return -EDEADLK;
WARN_ON(IS_ERR(c_st));
}
+
+ return 0;
}

/* release unclaimed pipeline resource */
@@ -1213,9 +1217,8 @@ int komeda_release_unclaimed_resources(struct komeda_pipeline *pipe,
if (WARN_ON(IS_ERR_OR_NULL(st)))
return -EINVAL;

- komeda_pipeline_unbound_components(pipe, st);
+ return komeda_pipeline_unbound_components(pipe, st);

- return 0;
}

void komeda_pipeline_disable(struct komeda_pipeline *pipe,
--
2.42.0