1. 18 5月, 2018 39 次提交
  2. 10 5月, 2018 1 次提交
    • L
      drm/nouveau: Fix deadlock in nv50_mstm_register_connector() · 352672db
      Lyude Paul 提交于
      Currently; we're grabbing all of the modesetting locks before adding MST
      connectors to fbdev. This isn't actually necessary, and causes a
      deadlock as well:
      
      ======================================================
      WARNING: possible circular locking dependency detected
      4.17.0-rc3Lyude-Test+ #1 Tainted: G           O
      ------------------------------------------------------
      kworker/1:0/18 is trying to acquire lock:
      00000000c832f62d (&helper->lock){+.+.}, at: drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
      
      but task is already holding lock:
      00000000942e28e2 (crtc_ww_class_mutex){+.+.}, at: drm_modeset_backoff+0x8e/0x1c0 [drm]
      
      which lock already depends on the new lock.
      
      the existing dependency chain (in reverse order) is:
      
      -> #3 (crtc_ww_class_mutex){+.+.}:
             ww_mutex_lock+0x43/0x80
             drm_modeset_lock+0x71/0x130 [drm]
             drm_helper_probe_single_connector_modes+0x7d/0x6b0 [drm_kms_helper]
             drm_setup_crtcs+0x15e/0xc90 [drm_kms_helper]
             __drm_fb_helper_initial_config_and_unlock+0x29/0x480 [drm_kms_helper]
             nouveau_fbcon_init+0x138/0x1a0 [nouveau]
             nouveau_drm_load+0x173/0x7e0 [nouveau]
             drm_dev_register+0x134/0x1c0 [drm]
             drm_get_pci_dev+0x8e/0x160 [drm]
             nouveau_drm_probe+0x1a9/0x230 [nouveau]
             pci_device_probe+0xcd/0x150
             driver_probe_device+0x30b/0x480
             __driver_attach+0xbc/0xe0
             bus_for_each_dev+0x67/0x90
             bus_add_driver+0x164/0x260
             driver_register+0x57/0xc0
             do_one_initcall+0x4d/0x323
             do_init_module+0x5b/0x1f8
             load_module+0x20e5/0x2ac0
             __do_sys_finit_module+0xb7/0xd0
             do_syscall_64+0x60/0x1b0
             entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      -> #2 (crtc_ww_class_acquire){+.+.}:
             drm_helper_probe_single_connector_modes+0x58/0x6b0 [drm_kms_helper]
             drm_setup_crtcs+0x15e/0xc90 [drm_kms_helper]
             __drm_fb_helper_initial_config_and_unlock+0x29/0x480 [drm_kms_helper]
             nouveau_fbcon_init+0x138/0x1a0 [nouveau]
             nouveau_drm_load+0x173/0x7e0 [nouveau]
             drm_dev_register+0x134/0x1c0 [drm]
             drm_get_pci_dev+0x8e/0x160 [drm]
             nouveau_drm_probe+0x1a9/0x230 [nouveau]
             pci_device_probe+0xcd/0x150
             driver_probe_device+0x30b/0x480
             __driver_attach+0xbc/0xe0
             bus_for_each_dev+0x67/0x90
             bus_add_driver+0x164/0x260
             driver_register+0x57/0xc0
             do_one_initcall+0x4d/0x323
             do_init_module+0x5b/0x1f8
             load_module+0x20e5/0x2ac0
             __do_sys_finit_module+0xb7/0xd0
             do_syscall_64+0x60/0x1b0
             entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      -> #1 (&dev->mode_config.mutex){+.+.}:
             drm_setup_crtcs+0x10c/0xc90 [drm_kms_helper]
             __drm_fb_helper_initial_config_and_unlock+0x29/0x480 [drm_kms_helper]
             nouveau_fbcon_init+0x138/0x1a0 [nouveau]
             nouveau_drm_load+0x173/0x7e0 [nouveau]
             drm_dev_register+0x134/0x1c0 [drm]
             drm_get_pci_dev+0x8e/0x160 [drm]
             nouveau_drm_probe+0x1a9/0x230 [nouveau]
             pci_device_probe+0xcd/0x150
             driver_probe_device+0x30b/0x480
             __driver_attach+0xbc/0xe0
             bus_for_each_dev+0x67/0x90
             bus_add_driver+0x164/0x260
             driver_register+0x57/0xc0
             do_one_initcall+0x4d/0x323
             do_init_module+0x5b/0x1f8
             load_module+0x20e5/0x2ac0
             __do_sys_finit_module+0xb7/0xd0
             do_syscall_64+0x60/0x1b0
             entry_SYSCALL_64_after_hwframe+0x49/0xbe
      
      -> #0 (&helper->lock){+.+.}:
             __mutex_lock+0x70/0x9d0
             drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
             nv50_mstm_register_connector+0x2c/0x50 [nouveau]
             drm_dp_add_port+0x2f5/0x420 [drm_kms_helper]
             drm_dp_send_link_address+0x155/0x1e0 [drm_kms_helper]
             drm_dp_add_port+0x33f/0x420 [drm_kms_helper]
             drm_dp_send_link_address+0x155/0x1e0 [drm_kms_helper]
             drm_dp_check_and_send_link_address+0x87/0xd0 [drm_kms_helper]
             drm_dp_mst_link_probe_work+0x4d/0x80 [drm_kms_helper]
             process_one_work+0x20d/0x650
             worker_thread+0x3a/0x390
             kthread+0x11e/0x140
             ret_from_fork+0x3a/0x50
      
      other info that might help us debug this:
      Chain exists of:
        &helper->lock --> crtc_ww_class_acquire --> crtc_ww_class_mutex
       Possible unsafe locking scenario:
             CPU0                    CPU1
             ----                    ----
        lock(crtc_ww_class_mutex);
                                     lock(crtc_ww_class_acquire);
                                     lock(crtc_ww_class_mutex);
        lock(&helper->lock);
      
       *** DEADLOCK ***
      5 locks held by kworker/1:0/18:
       #0: 000000004a05cd50 ((wq_completion)"events_long"){+.+.}, at: process_one_work+0x187/0x650
       #1: 00000000601c11d1 ((work_completion)(&mgr->work)){+.+.}, at: process_one_work+0x187/0x650
       #2: 00000000586ca0df (&dev->mode_config.mutex){+.+.}, at: drm_modeset_lock_all+0x3a/0x1b0 [drm]
       #3: 00000000d3ca0ffa (crtc_ww_class_acquire){+.+.}, at: drm_modeset_lock_all+0x44/0x1b0 [drm]
       #4: 00000000942e28e2 (crtc_ww_class_mutex){+.+.}, at: drm_modeset_backoff+0x8e/0x1c0 [drm]
      
      stack backtrace:
      CPU: 1 PID: 18 Comm: kworker/1:0 Tainted: G           O      4.17.0-rc3Lyude-Test+ #1
      Hardware name: Gateway FX6840/FX6840, BIOS P01-A3         05/17/2010
      Workqueue: events_long drm_dp_mst_link_probe_work [drm_kms_helper]
      Call Trace:
       dump_stack+0x85/0xcb
       print_circular_bug.isra.38+0x1ce/0x1db
       __lock_acquire+0x128f/0x1350
       ? lock_acquire+0x9f/0x200
       ? lock_acquire+0x9f/0x200
       ? __ww_mutex_lock.constprop.13+0x8f/0x1000
       lock_acquire+0x9f/0x200
       ? drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
       ? drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
       __mutex_lock+0x70/0x9d0
       ? drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
       ? ww_mutex_lock+0x43/0x80
       ? _cond_resched+0x15/0x30
       ? ww_mutex_lock+0x43/0x80
       ? drm_modeset_lock+0xb2/0x130 [drm]
       ? drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
       drm_fb_helper_add_one_connector+0x2a/0x60 [drm_kms_helper]
       nv50_mstm_register_connector+0x2c/0x50 [nouveau]
       drm_dp_add_port+0x2f5/0x420 [drm_kms_helper]
       ? mark_held_locks+0x50/0x80
       ? kfree+0xcf/0x2a0
       ? drm_dp_check_mstb_guid+0xd6/0x120 [drm_kms_helper]
       ? trace_hardirqs_on_caller+0xed/0x180
       ? drm_dp_check_mstb_guid+0xd6/0x120 [drm_kms_helper]
       drm_dp_send_link_address+0x155/0x1e0 [drm_kms_helper]
       drm_dp_add_port+0x33f/0x420 [drm_kms_helper]
       ? nouveau_connector_aux_xfer+0x7c/0xb0 [nouveau]
       ? find_held_lock+0x2d/0x90
       ? drm_dp_dpcd_access+0xd9/0xf0 [drm_kms_helper]
       ? __mutex_unlock_slowpath+0x3b/0x280
       ? drm_dp_dpcd_access+0xd9/0xf0 [drm_kms_helper]
       drm_dp_send_link_address+0x155/0x1e0 [drm_kms_helper]
       drm_dp_check_and_send_link_address+0x87/0xd0 [drm_kms_helper]
       drm_dp_mst_link_probe_work+0x4d/0x80 [drm_kms_helper]
       process_one_work+0x20d/0x650
       worker_thread+0x3a/0x390
       ? process_one_work+0x650/0x650
       kthread+0x11e/0x140
       ? kthread_create_worker_on_cpu+0x50/0x50
       ret_from_fork+0x3a/0x50
      
      Taking example from i915, the only time we need to hold any modesetting
      locks is when changing the port on the mstc, and in that case we only
      need to hold the connection mutex.
      Signed-off-by: NLyude Paul <lyude@redhat.com>
      Cc: Karol Herbst <kherbst@redhat.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: NLyude Paul <lyude@redhat.com>
      Signed-off-by: NBen Skeggs <bskeggs@redhat.com>
      352672db