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drm/i915: fix deadlock on lid open
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commit e2c8b87 moved modeset locking inside resume/suspend
functions, but missed a code path only executed on lid close/open
on older hardware. The result was a deadlock when closing and
opening the lid without suspending on such hardware:

 =============================================
 [ INFO: possible recursive locking detected ]
 4.6.0-rc1 torvalds#385 Not tainted
 ---------------------------------------------
 kworker/0:3/88 is trying to acquire lock:
  (&dev->mode_config.mutex){+.+.+.}, at: [<ffffffffa063e6a4>] intel_display_resume+0x4a/0x12f [i915]

 but task is already holding lock:
  (&dev->mode_config.mutex){+.+.+.}, at: [<ffffffffa02d0d4f>] drm_modeset_lock_all+0x3e/0xa6 [drm]

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&dev->mode_config.mutex);
   lock(&dev->mode_config.mutex);

  *** DEADLOCK ***

  May be due to missing lock nesting notation

 7 locks held by kworker/0:3/88:
  #0:  ("kacpi_notify"){++++.+}, at: [<ffffffff81068dfc>] process_one_work+0x14a/0x50b
  plbossart#1:  ((&dpc->work)plbossart#2){+.+.+.}, at: [<ffffffff81068dfc>] process_one_work+0x14a/0x50b
  plbossart#2:  ((acpi_lid_notifier).rwsem){++++.+}, at: [<ffffffff8106f874>] __blocking_notifier_call_chain+0x34/0x65
  plbossart#3:  (&dev_priv->modeset_restore_lock){+.+.+.}, at: [<ffffffffa0664cf6>] intel_lid_notify+0x3c/0xd9 [i915]
  plbossart#4:  (&dev->mode_config.mutex){+.+.+.}, at: [<ffffffffa02d0d4f>] drm_modeset_lock_all+0x3e/0xa6 [drm]
  plbossart#5:  (crtc_ww_class_acquire){+.+.+.}, at: [<ffffffffa02d0d59>] drm_modeset_lock_all+0x48/0xa6 [drm]
  plbossart#6:  (crtc_ww_class_mutex){+.+.+.}, at: [<ffffffffa02d0b2a>] modeset_lock+0x13c/0x1cd [drm]

 stack backtrace:
 CPU: 0 PID: 88 Comm: kworker/0:3 Not tainted 4.6.0-rc1 torvalds#385
 Hardware name: LENOVO 2776LEG/2776LEG, BIOS 6EET55WW (3.15 ) 12/19/2011
 Workqueue: kacpi_notify acpi_os_execute_deferred
  0000000000000000 ffff88022fd5f990 ffffffff8124af06 ffffffff825b39c0
  ffffffff825b39c0 ffff88022fd5fa60 ffffffff8108f547 ffff88022fd5fa70
  000000008108e817 ffff880230236cc0 0000000000000000 ffffffff825b39c0
 Call Trace:
  [<ffffffff8124af06>] dump_stack+0x67/0x90
  [<ffffffff8108f547>] __lock_acquire+0xdb5/0xf71
  [<ffffffff8108bd2c>] ? look_up_lock_class+0xbe/0x10a
  [<ffffffff8108fae2>] lock_acquire+0x137/0x1cb
  [<ffffffff8108fae2>] ? lock_acquire+0x137/0x1cb
  [<ffffffffa063e6a4>] ? intel_display_resume+0x4a/0x12f [i915]
  [<ffffffff8148202f>] mutex_lock_nested+0x7e/0x3a4
  [<ffffffffa063e6a4>] ? intel_display_resume+0x4a/0x12f [i915]
  [<ffffffffa063e6a4>] ? intel_display_resume+0x4a/0x12f [i915]
  [<ffffffffa02d0b2a>] ? modeset_lock+0x13c/0x1cd [drm]
  [<ffffffffa063e6a4>] intel_display_resume+0x4a/0x12f [i915]
  [<ffffffffa063e6a4>] ? intel_display_resume+0x4a/0x12f [i915]
  [<ffffffffa02d0b2a>] ? modeset_lock+0x13c/0x1cd [drm]
  [<ffffffffa02d0b2a>] ? modeset_lock+0x13c/0x1cd [drm]
  [<ffffffffa02d0bf7>] ? drm_modeset_lock+0x17/0x24 [drm]
  [<ffffffffa02d0c8b>] ? drm_modeset_lock_all_ctx+0x87/0xa1 [drm]
  [<ffffffffa0664d6a>] intel_lid_notify+0xb0/0xd9 [i915]
  [<ffffffff8106f4c6>] notifier_call_chain+0x4a/0x6c
  [<ffffffff8106f88d>] __blocking_notifier_call_chain+0x4d/0x65
  [<ffffffff8106f8b9>] blocking_notifier_call_chain+0x14/0x16
  [<ffffffffa0011215>] acpi_lid_send_state+0x83/0xad [button]
  [<ffffffffa00112a6>] acpi_button_notify+0x41/0x132 [button]
  [<ffffffff812b07df>] acpi_device_notify+0x19/0x1b
  [<ffffffff812c8570>] acpi_ev_notify_dispatch+0x49/0x64
  [<ffffffff812ab9fb>] acpi_os_execute_deferred+0x14/0x20
  [<ffffffff81068f17>] process_one_work+0x265/0x50b
  [<ffffffff810696f5>] worker_thread+0x1fc/0x2dd
  [<ffffffff810694f9>] ? rescuer_thread+0x309/0x309
  [<ffffffff810694f9>] ? rescuer_thread+0x309/0x309
  [<ffffffff8106e2d6>] kthread+0xe0/0xe8
  [<ffffffff8107bc47>] ? local_clock+0x19/0x22
  [<ffffffff81484f42>] ret_from_fork+0x22/0x40
  [<ffffffff8106e1f6>] ? kthread_create_on_node+0x1b5/0x1b5

Fixes: e2c8b87 ("drm/i915: Use atomic helpers for suspend, v2.")
Cc: Maarten Lankhorst <[email protected]>
Signed-off-by: Bjørn Mork <[email protected]>
Signed-off-by: Maarten Lankhorst <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]
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bmork authored and mlankhorst committed Mar 30, 2016
1 parent 68d4aee commit 9f54d4b
Showing 1 changed file with 1 addition and 4 deletions.
5 changes: 1 addition & 4 deletions drivers/gpu/drm/i915/intel_lvds.c
Original file line number Diff line number Diff line change
Expand Up @@ -472,11 +472,8 @@ static int intel_lid_notify(struct notifier_block *nb, unsigned long val,
* and as part of the cleanup in the hw state restore we also redisable
* the vga plane.
*/
if (!HAS_PCH_SPLIT(dev)) {
drm_modeset_lock_all(dev);
if (!HAS_PCH_SPLIT(dev))
intel_display_resume(dev);
drm_modeset_unlock_all(dev);
}

dev_priv->modeset_restore = MODESET_DONE;

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