[PATCH 6/9] drm/nouveau: Convert event handler list to RCU
Lockdep report [1] correctly identifies a potential deadlock between
nouveau_drm_vblank_enable() and nouveau_drm_vblank_handler() due
to inverted lock order of event->lock with drm core's
dev->vblank_time_lock.
Fix vblank event deadlock by converting event handler list to RCU.
List updates remain serialized by event->lock.
List traversal & handler execution is lockless which prevents
inverted lock order problems with the drm core.
Safe deletion of the event handler is accomplished with
synchronize_rcu() for those handlers stored in nouveau_object-based
containers (nouveau_drm & nv50_/nvc0_software_context); otherwise,
with kfree_rcu (for nouveau_connector & uevent temporary handlers).
[1]
==
[ INFO: possible circular locking dependency detected ]
3.10.0-0+tip-xeon+lockdep #0+tip Not tainted
---
swapper/7/0 is trying to acquire lock:
(&(&dev->vblank_time_lock)->rlock){-.}, at: []
drm_handle_vblank+0x69/0x400 [drm]
but task is already holding lock:
(&(&event->lock)->rlock){-.}, at: []
nouveau_event_trigger+0x4d/0xd0 [nouveau]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&(&event->lock)->rlock){-.}:
[] lock_acquire+0x92/0x1f0
[] _raw_spin_lock_irqsave+0x46/0x60
[] nouveau_event_get+0x27/0xa0 [nouveau]
[] nouveau_drm_vblank_enable+0x8d/0xf0 [nouveau]
[] drm_vblank_get+0xf8/0x2c0 [drm]
[] drm_wait_vblank+0x84/0x6f0 [drm]
[] drm_ioctl+0x559/0x690 [drm]
[] do_vfs_ioctl+0x97/0x590
[] SyS_ioctl+0x91/0xb0
[] system_call_fastpath+0x16/0x1b
-> #0 (&(&dev->vblank_time_lock)->rlock){-.}:
[] __lock_acquire+0x1c43/0x1d30
[] lock_acquire+0x92/0x1f0
[] _raw_spin_lock_irqsave+0x46/0x60
[] drm_handle_vblank+0x69/0x400 [drm]
[] nouveau_drm_vblank_handler+0x27/0x30 [nouveau]
[] nouveau_event_trigger+0x90/0xd0 [nouveau]
[] nv50_disp_intr+0xdd/0x230 [nouveau]
[] nouveau_mc_intr+0xa1/0x100 [nouveau]
[] handle_irq_event_percpu+0x6c/0x3d0
[] handle_irq_event+0x48/0x70
[] handle_fasteoi_irq+0x5a/0x100
[] handle_irq+0x22/0x40
[] do_IRQ+0x5a/0xd0
[] ret_from_intr+0x0/0x13
[] arch_cpu_idle+0x26/0x30
[] cpu_startup_entry+0xce/0x410
[] start_secondary+0x255/0x25c
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0CPU1
lock(&(&event->lock)->rlock);
lock(&(&dev->vblank_time_lock)->rlock);
lock(&(&event->lock)->rlock);
lock(&(&dev->vblank_time_lock)->rlock);
*** DEADLOCK ***
1 lock held by swapper/7/0:
#0: (&(&event->lock)->rlock){-.}, at: []
nouveau_event_trigger+0x4d/0xd0 [nouveau]
stack backtrace:
CPU: 7 PID: 0 Comm: swapper/7 Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip
Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11
04/30/2012
821ccf60 8802bfdc3b08 81755f39 8802bfdc3b58
8174f526 0002 8802bfdc3be8 8802b330a7f8
8802b330a820 8802b330a7f8 0001
Call Trace:
[] dump_stack+0x19/0x1b
[] print_circular_bug+0x1fb/0x20c
[] __lock_acquire+0x1c43/0x1d30
[] ? trace_hardirqs_off+0xd/0x10
[] ? flat_send_IPI_mask+0x88/0xa0
[] lock_acquire+0x92/0x1f0
[] ? drm_handle_vblank+0x69/0x400 [drm]
[] _raw_spin_lock_irqsave+0x46/0x60
[] ? drm_handle_vblank+0x69/0x400 [drm]
[] drm_handle_vblank+0x69/0x400 [drm]
[] nouveau_drm_vblank_handler+0x27/0x30 [nouveau]
[] nouveau_event_trigger+0x90/0xd0 [nouveau]
[] nv50_disp_intr+0xdd/0x230 [nouveau]
[] ? _raw_spin_unlock_irqrestore+0x42/0x80
[] ? __hrtimer_start_range_ns+0x16c/0x530
[] nouveau_mc_intr+0xa1/0x100 [nouveau]
[] handle_irq_event_percpu+0x6c/0x3d0
[] handle_irq_event+0x48/0x70
[] ? handle_fasteoi_irq+0x1e/0x100
[] handle_fasteoi_irq+0x5a/0x100
[] handle_irq+0x22/0x40
[] do_IRQ+0x5a/0xd0
[] common_interrupt+0x6f/0x6f
[] ? default_idle+0x1d/0x290
[] ? default_idle+0x1b/0x290
[] arch_cpu_idle+0x26/0x30
[] cpu_startup_entry+0xce/0x410
[] ? clockevents_register_device+0xdc/0x140
[] start_secondary+0x255/0x25c
Reported-by: Dave Jones
Signed-off-by: Peter Hurley
---
drivers/gpu/drm/nouveau/core/core/event.c | 22 +++---
.../gpu/drm/nouveau/core/engine/software/nv50.c| 1 +
.../gpu/drm/nouveau/core/engine/software/nvc0.c| 1 +
drivers/gpu/drm/nouveau/core/include/core/event.h | 1 +
drivers/gpu/drm/nouveau/nouveau_connector.c| 2 +-
drivers/gpu/drm/nouveau/nouveau_drm.c | 1 +
6 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/core/core/event.c
b/drivers/gpu/drm/nouveau/core/core/event.c
index 4cd1ebe..ce0a0ef 100644
--- a/drive
[PATCH 6/9] drm/nouveau: Convert event handler list to RCU
Lockdep report [1] correctly identifies a potential deadlock between
nouveau_drm_vblank_enable() and nouveau_drm_vblank_handler() due
to inverted lock order of event->lock with drm core's
dev->vblank_time_lock.
Fix vblank event deadlock by converting event handler list to RCU.
List updates remain serialized by event->lock.
List traversal & handler execution is lockless which prevents
inverted lock order problems with the drm core.
Safe deletion of the event handler is accomplished with
synchronize_rcu() for those handlers stored in nouveau_object-based
containers (nouveau_drm & nv50_/nvc0_software_context); otherwise,
with kfree_rcu (for nouveau_connector & uevent temporary handlers).
[1]
==
[ INFO: possible circular locking dependency detected ]
3.10.0-0+tip-xeon+lockdep #0+tip Not tainted
---
swapper/7/0 is trying to acquire lock:
(&(&dev->vblank_time_lock)->rlock){-.}, at: []
drm_handle_vblank+0x69/0x400 [drm]
but task is already holding lock:
(&(&event->lock)->rlock){-.}, at: []
nouveau_event_trigger+0x4d/0xd0 [nouveau]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&(&event->lock)->rlock){-.}:
[] lock_acquire+0x92/0x1f0
[] _raw_spin_lock_irqsave+0x46/0x60
[] nouveau_event_get+0x27/0xa0 [nouveau]
[] nouveau_drm_vblank_enable+0x8d/0xf0 [nouveau]
[] drm_vblank_get+0xf8/0x2c0 [drm]
[] drm_wait_vblank+0x84/0x6f0 [drm]
[] drm_ioctl+0x559/0x690 [drm]
[] do_vfs_ioctl+0x97/0x590
[] SyS_ioctl+0x91/0xb0
[] system_call_fastpath+0x16/0x1b
-> #0 (&(&dev->vblank_time_lock)->rlock){-.}:
[] __lock_acquire+0x1c43/0x1d30
[] lock_acquire+0x92/0x1f0
[] _raw_spin_lock_irqsave+0x46/0x60
[] drm_handle_vblank+0x69/0x400 [drm]
[] nouveau_drm_vblank_handler+0x27/0x30 [nouveau]
[] nouveau_event_trigger+0x90/0xd0 [nouveau]
[] nv50_disp_intr+0xdd/0x230 [nouveau]
[] nouveau_mc_intr+0xa1/0x100 [nouveau]
[] handle_irq_event_percpu+0x6c/0x3d0
[] handle_irq_event+0x48/0x70
[] handle_fasteoi_irq+0x5a/0x100
[] handle_irq+0x22/0x40
[] do_IRQ+0x5a/0xd0
[] ret_from_intr+0x0/0x13
[] arch_cpu_idle+0x26/0x30
[] cpu_startup_entry+0xce/0x410
[] start_secondary+0x255/0x25c
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0CPU1
lock(&(&event->lock)->rlock);
lock(&(&dev->vblank_time_lock)->rlock);
lock(&(&event->lock)->rlock);
lock(&(&dev->vblank_time_lock)->rlock);
*** DEADLOCK ***
1 lock held by swapper/7/0:
#0: (&(&event->lock)->rlock){-.}, at: []
nouveau_event_trigger+0x4d/0xd0 [nouveau]
stack backtrace:
CPU: 7 PID: 0 Comm: swapper/7 Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip
Hardware name: Dell Inc. Precision WorkStation T5400 /0RW203, BIOS A11
04/30/2012
821ccf60 8802bfdc3b08 81755f39 8802bfdc3b58
8174f526 0002 8802bfdc3be8 8802b330a7f8
8802b330a820 8802b330a7f8 0001
Call Trace:
[] dump_stack+0x19/0x1b
[] print_circular_bug+0x1fb/0x20c
[] __lock_acquire+0x1c43/0x1d30
[] ? trace_hardirqs_off+0xd/0x10
[] ? flat_send_IPI_mask+0x88/0xa0
[] lock_acquire+0x92/0x1f0
[] ? drm_handle_vblank+0x69/0x400 [drm]
[] _raw_spin_lock_irqsave+0x46/0x60
[] ? drm_handle_vblank+0x69/0x400 [drm]
[] drm_handle_vblank+0x69/0x400 [drm]
[] nouveau_drm_vblank_handler+0x27/0x30 [nouveau]
[] nouveau_event_trigger+0x90/0xd0 [nouveau]
[] nv50_disp_intr+0xdd/0x230 [nouveau]
[] ? _raw_spin_unlock_irqrestore+0x42/0x80
[] ? __hrtimer_start_range_ns+0x16c/0x530
[] nouveau_mc_intr+0xa1/0x100 [nouveau]
[] handle_irq_event_percpu+0x6c/0x3d0
[] handle_irq_event+0x48/0x70
[] ? handle_fasteoi_irq+0x1e/0x100
[] handle_fasteoi_irq+0x5a/0x100
[] handle_irq+0x22/0x40
[] do_IRQ+0x5a/0xd0
[] common_interrupt+0x6f/0x6f
[] ? default_idle+0x1d/0x290
[] ? default_idle+0x1b/0x290
[] arch_cpu_idle+0x26/0x30
[] cpu_startup_entry+0xce/0x410
[] ? clockevents_register_device+0xdc/0x140
[] start_secondary+0x255/0x25c
Reported-by: Dave Jones
Signed-off-by: Peter Hurley
---
drivers/gpu/drm/nouveau/core/core/event.c | 22 +++---
.../gpu/drm/nouveau/core/engine/software/nv50.c| 1 +
.../gpu/drm/nouveau/core/engine/software/nvc0.c| 1 +
drivers/gpu/drm/nouveau/core/include/core/event.h | 1 +
drivers/gpu/drm/nouveau/nouveau_connector.c| 2 +-
drivers/gpu/drm/nouveau/nouveau_drm.c | 1 +
6 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/core/core/event.c
b/drivers/gpu/drm/nouveau/core/core/event.c
index 4cd1ebe..ce0a0ef 100644
--- a/drive
