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Message-Id: <20200416131356.550865910@linuxfoundation.org>
Date: Thu, 16 Apr 2020 15:24:58 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Lyude Paul <lyude@...hat.com>,
Sean Paul <sean@...rly.run>, Wayne Lin <Wayne.Lin@....com>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.5 247/257] Revert "drm/dp_mst: Remove VCPI while disabling topology mgr"
[ Upstream commit a86675968e2300fb567994459da3dbc4cd1b322a ]
This reverts commit 64e62bdf04ab8529f45ed0a85122c703035dec3a.
This commit ends up causing some lockdep splats due to trying to grab the
payload lock while holding the mgr's lock:
[ 54.010099]
[ 54.011765] ======================================================
[ 54.018670] WARNING: possible circular locking dependency detected
[ 54.025577] 5.5.0-rc6-02274-g77381c23ee63 #47 Not tainted
[ 54.031610] ------------------------------------------------------
[ 54.038516] kworker/1:6/1040 is trying to acquire lock:
[ 54.044354] ffff888272af3228 (&mgr->payload_lock){+.+.}, at:
drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4
[ 54.054957]
[ 54.054957] but task is already holding lock:
[ 54.061473] ffff888272af3060 (&mgr->lock){+.+.}, at:
drm_dp_mst_topology_mgr_set_mst+0x3c/0x2e4
[ 54.071193]
[ 54.071193] which lock already depends on the new lock.
[ 54.071193]
[ 54.080334]
[ 54.080334] the existing dependency chain (in reverse order) is:
[ 54.088697]
[ 54.088697] -> #1 (&mgr->lock){+.+.}:
[ 54.094440] __mutex_lock+0xc3/0x498
[ 54.099015] drm_dp_mst_topology_get_port_validated+0x25/0x80
[ 54.106018] drm_dp_update_payload_part1+0xa2/0x2e2
[ 54.112051] intel_mst_pre_enable_dp+0x144/0x18f
[ 54.117791] intel_encoders_pre_enable+0x63/0x70
[ 54.123532] hsw_crtc_enable+0xa1/0x722
[ 54.128396] intel_update_crtc+0x50/0x194
[ 54.133455] skl_commit_modeset_enables+0x40c/0x540
[ 54.139485] intel_atomic_commit_tail+0x5f7/0x130d
[ 54.145418] intel_atomic_commit+0x2c8/0x2d8
[ 54.150770] drm_atomic_helper_set_config+0x5a/0x70
[ 54.156801] drm_mode_setcrtc+0x2ab/0x833
[ 54.161862] drm_ioctl+0x2e5/0x424
[ 54.166242] vfs_ioctl+0x21/0x2f
[ 54.170426] do_vfs_ioctl+0x5fb/0x61e
[ 54.175096] ksys_ioctl+0x55/0x75
[ 54.179377] __x64_sys_ioctl+0x1a/0x1e
[ 54.184146] do_syscall_64+0x5c/0x6d
[ 54.188721] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 54.194946]
[ 54.194946] -> #0 (&mgr->payload_lock){+.+.}:
[ 54.201463]
[ 54.201463] other info that might help us debug this:
[ 54.201463]
[ 54.210410] Possible unsafe locking scenario:
[ 54.210410]
[ 54.217025] CPU0 CPU1
[ 54.222082] ---- ----
[ 54.227138] lock(&mgr->lock);
[ 54.230643] lock(&mgr->payload_lock);
[ 54.237742] lock(&mgr->lock);
[ 54.244062] lock(&mgr->payload_lock);
[ 54.248346]
[ 54.248346] *** DEADLOCK ***
[ 54.248346]
[ 54.254959] 7 locks held by kworker/1:6/1040:
[ 54.259822] #0: ffff888275c4f528 ((wq_completion)events){+.+.},
at: worker_thread+0x455/0x6e2
[ 54.269451] #1: ffffc9000119beb0
((work_completion)(&(&dev_priv->hotplug.hotplug_work)->work)){+.+.},
at: worker_thread+0x455/0x6e2
[ 54.282768] #2: ffff888272a403f0 (&dev->mode_config.mutex){+.+.},
at: i915_hotplug_work_func+0x4b/0x2be
[ 54.293368] #3: ffffffff824fc6c0 (drm_connector_list_iter){.+.+},
at: i915_hotplug_work_func+0x17e/0x2be
[ 54.304061] #4: ffffc9000119bc58 (crtc_ww_class_acquire){+.+.},
at: drm_helper_probe_detect_ctx+0x40/0xfd
[ 54.314855] #5: ffff888272a40470 (crtc_ww_class_mutex){+.+.}, at:
drm_modeset_lock+0x74/0xe2
[ 54.324385] #6: ffff888272af3060 (&mgr->lock){+.+.}, at:
drm_dp_mst_topology_mgr_set_mst+0x3c/0x2e4
[ 54.334597]
[ 54.334597] stack backtrace:
[ 54.339464] CPU: 1 PID: 1040 Comm: kworker/1:6 Not tainted
5.5.0-rc6-02274-g77381c23ee63 #47
[ 54.348893] Hardware name: Google Fizz/Fizz, BIOS
Google_Fizz.10139.39.0 01/04/2018
[ 54.357451] Workqueue: events i915_hotplug_work_func
[ 54.362995] Call Trace:
[ 54.365724] dump_stack+0x71/0x9c
[ 54.369427] check_noncircular+0x91/0xbc
[ 54.373809] ? __lock_acquire+0xc9e/0xf66
[ 54.378286] ? __lock_acquire+0xc9e/0xf66
[ 54.382763] ? lock_acquire+0x175/0x1ac
[ 54.387048] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4
[ 54.393177] ? __mutex_lock+0xc3/0x498
[ 54.397362] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4
[ 54.403492] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4
[ 54.409620] ? drm_dp_dpcd_access+0xd9/0x101
[ 54.414390] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4
[ 54.420517] ? drm_dp_mst_topology_mgr_set_mst+0x218/0x2e4
[ 54.426645] ? intel_digital_port_connected+0x34d/0x35c
[ 54.432482] ? intel_dp_detect+0x227/0x44e
[ 54.437056] ? ww_mutex_lock+0x49/0x9a
[ 54.441242] ? drm_helper_probe_detect_ctx+0x75/0xfd
[ 54.446789] ? intel_encoder_hotplug+0x4b/0x97
[ 54.451752] ? intel_ddi_hotplug+0x61/0x2e0
[ 54.456423] ? mark_held_locks+0x53/0x68
[ 54.460803] ? _raw_spin_unlock_irqrestore+0x3a/0x51
[ 54.466347] ? lockdep_hardirqs_on+0x187/0x1a4
[ 54.471310] ? drm_connector_list_iter_next+0x89/0x9a
[ 54.476953] ? i915_hotplug_work_func+0x206/0x2be
[ 54.482208] ? worker_thread+0x4d5/0x6e2
[ 54.486587] ? worker_thread+0x455/0x6e2
[ 54.490966] ? queue_work_on+0x64/0x64
[ 54.495151] ? kthread+0x1e9/0x1f1
[ 54.498946] ? queue_work_on+0x64/0x64
[ 54.503130] ? kthread_unpark+0x5e/0x5e
[ 54.507413] ? ret_from_fork+0x3a/0x50
The proper fix for this is probably cleanup the VCPI allocations when we're
enabling the topology, or on the first payload allocation. For now though,
let's just revert.
Signed-off-by: Lyude Paul <lyude@...hat.com>
Fixes: 64e62bdf04ab ("drm/dp_mst: Remove VCPI while disabling topology mgr")
Cc: Sean Paul <sean@...rly.run>
Cc: Wayne Lin <Wayne.Lin@....com>
Reviewed-by: Sean Paul <sean@...rly.run>
Link: https://patchwork.freedesktop.org/patch/msgid/20200117205149.97262-1-lyude@redhat.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 12 ------------
1 file changed, 12 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 4a65ef8d8bff3..c4b692dff5956 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3437,7 +3437,6 @@ static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8 dp_link_count)
int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
{
int ret = 0;
- int i = 0;
struct drm_dp_mst_branch *mstb = NULL;
mutex_lock(&mgr->lock);
@@ -3498,21 +3497,10 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
/* this can fail if the device is gone */
drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
ret = 0;
- mutex_lock(&mgr->payload_lock);
memset(mgr->payloads, 0, mgr->max_payloads * sizeof(struct drm_dp_payload));
mgr->payload_mask = 0;
set_bit(0, &mgr->payload_mask);
- for (i = 0; i < mgr->max_payloads; i++) {
- struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
-
- if (vcpi) {
- vcpi->vcpi = 0;
- vcpi->num_slots = 0;
- }
- mgr->proposed_vcpis[i] = NULL;
- }
mgr->vcpi_mask = 0;
- mutex_unlock(&mgr->payload_lock);
}
out_unlock:
--
2.20.1
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