Hi,
Good catch (both the previous patch as well as this one).
I've one small comment inline:
On 12-01-17 03:25, Lyude wrote:
Resuming from RPM can happen while already holding
dev->mode_config.mutex. This means we can't actually handle fbcon in
any RPM resume workers, since restoring fbcon requires grabbing
dev->mode_config.mutex again. So move the fbcon suspend/resume code into
it's own worker, and rely on that instead to avoid deadlocking.
This fixes more deadlocks for runtime suspending the GPU on the ThinkPad
W541. Reproduction recipe:
- Get a machine with both optimus and a nvidia card with connectors
attached to it
- Wait for the nvidia GPU to suspend
- Attempt to manually reprobe any of the connectors on the nvidia GPU
using sysfs
- *deadlock*
Signed-off-by: Lyude <lyude@xxxxxxxxxx>
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Cc: Kilian Singer <kilian.singer@xxxxxxxxxxxxxxxxxxxxxx>
Cc: Lukas Wunner <lukas@xxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxxxx>
---
drivers/gpu/drm/nouveau/nouveau_drv.h | 2 ++
drivers/gpu/drm/nouveau/nouveau_fbcon.c | 43 ++++++++++++++++++++++++++-------
2 files changed, 36 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 8d5ed5b..42c1fa5 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -165,6 +165,8 @@ struct nouveau_drm {
struct backlight_device *backlight;
struct list_head bl_connectors;
struct work_struct hpd_work;
+ struct work_struct fbcon_work;
+ int fbcon_new_state;
#ifdef CONFIG_ACPI
struct notifier_block acpi_nb;
#endif
diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index 2f2a3dc..87cd30b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -470,19 +470,43 @@ static const struct drm_fb_helper_funcs nouveau_fbcon_helper_funcs = {
.fb_probe = nouveau_fbcon_create,
};
+static void
+nouveau_fbcon_set_suspend_work(struct work_struct *work)
+{
+ struct nouveau_drm *drm = container_of(work, typeof(*drm), fbcon_work);
+ int state = drm->fbcon_new_state;
The compiler may decide to optimize away this variable
and simply use drm->fbcon_new_state in the if-s below,
which is racy. I would fix this by making
drm->fbcon_new_state an atomic_t and using
atomic_read(&drm->fbcon_new_state) here.
(and atomic_set below).
Regards,
Hans
+
+ if (state == FBINFO_STATE_RUNNING)
+ pm_runtime_get_sync(drm->dev->dev);
+
+ console_lock();
+ if (state == FBINFO_STATE_RUNNING)
+ nouveau_fbcon_accel_restore(drm->dev);
+ drm_fb_helper_set_suspend(&drm->fbcon->helper, state);
+ if (state != FBINFO_STATE_RUNNING)
+ nouveau_fbcon_accel_save_disable(drm->dev);
+ console_unlock();
+
+ if (state == FBINFO_STATE_RUNNING) {
+ pm_runtime_mark_last_busy(drm->dev->dev);
+ pm_runtime_put_sync(drm->dev->dev);
+ }
+}
+
void
nouveau_fbcon_set_suspend(struct drm_device *dev, int state)
{
struct nouveau_drm *drm = nouveau_drm(dev);
- if (drm->fbcon) {
- console_lock();
- if (state == FBINFO_STATE_RUNNING)
- nouveau_fbcon_accel_restore(dev);
- drm_fb_helper_set_suspend(&drm->fbcon->helper, state);
- if (state != FBINFO_STATE_RUNNING)
- nouveau_fbcon_accel_save_disable(dev);
- console_unlock();
- }
+
+ if (!drm->fbcon)
+ return;
+
+ drm->fbcon_new_state = state;
+ /* Since runtime resume can happen as a result of a sysfs operation,
+ * it's possible we already have the console locked. So handle fbcon
+ * init/deinit from a seperate work thread
+ */
+ schedule_work(&drm->fbcon_work);
}
int
@@ -502,6 +526,7 @@ nouveau_fbcon_init(struct drm_device *dev)
return -ENOMEM;
drm->fbcon = fbcon;
+ INIT_WORK(&drm->fbcon_work, nouveau_fbcon_set_suspend_work);
drm_fb_helper_prepare(dev, &fbcon->helper, &nouveau_fbcon_helper_funcs);
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