drm/i915: Replace wait-on-mutex with wait-on-bit in reset worker
Since we have a cooperative mode now with a direct reset, we can avoid
the contention on struct_mutex and instead try then sleep on the
I915_RESET_IN_PROGRESS bit. If the mutex is held and that bit is
cleared, all is fine. Otherwise, we sleep for a bit and try again. In
the worst case we sleep for an extra second waiting for the mutex to be
released (no one touching the GPU is allowed the struct_mutex whilst the
I915_RESET_IN_PROGRESS bit is set). But when we have a direct reset,
this allows us to clean up the reset worker faster.
v2: Remember to call wake_up_bit() after changing (for the faster wakeup
as promised)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160909131201.16673-12-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index ff4173e..f2614b2 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1726,8 +1726,8 @@
* i915_reset - reset chip after a hang
* @dev: drm device to reset
*
- * Reset the chip. Useful if a hang is detected. Returns zero on successful
- * reset or otherwise an error code.
+ * Reset the chip. Useful if a hang is detected. Marks the device as wedged
+ * on failure.
*
* Caller must hold the struct_mutex.
*
@@ -1739,7 +1739,7 @@
* - re-init interrupt state
* - re-init display
*/
-int i915_reset(struct drm_i915_private *dev_priv)
+void i915_reset(struct drm_i915_private *dev_priv)
{
struct drm_device *dev = &dev_priv->drm;
struct i915_gpu_error *error = &dev_priv->gpu_error;
@@ -1748,7 +1748,7 @@
lockdep_assert_held(&dev->struct_mutex);
if (!test_and_clear_bit(I915_RESET_IN_PROGRESS, &error->flags))
- return test_bit(I915_WEDGED, &error->flags) ? -EIO : 0;
+ return;
/* Clear any previous failed attempts at recovery. Time to try again. */
__clear_bit(I915_WEDGED, &error->flags);
@@ -1798,11 +1798,13 @@
intel_sanitize_gt_powersave(dev_priv);
intel_autoenable_gt_powersave(dev_priv);
- return 0;
+wakeup:
+ wake_up_bit(&error->flags, I915_RESET_IN_PROGRESS);
+ return;
error:
set_bit(I915_WEDGED, &error->flags);
- return ret;
+ goto wakeup;
}
static int i915_pm_suspend(struct device *kdev)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 15f1977..9a9f07f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2884,7 +2884,7 @@
#endif
extern int intel_gpu_reset(struct drm_i915_private *dev_priv, u32 engine_mask);
extern bool intel_has_gpu_reset(struct drm_i915_private *dev_priv);
-extern int i915_reset(struct drm_i915_private *dev_priv);
+extern void i915_reset(struct drm_i915_private *dev_priv);
extern int intel_guc_reset(struct drm_i915_private *dev_priv);
extern void intel_engine_init_hangcheck(struct intel_engine_cs *engine);
extern unsigned long i915_chipset_val(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 2c7cb50..ef2d402 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2497,7 +2497,6 @@
char *error_event[] = { I915_ERROR_UEVENT "=1", NULL };
char *reset_event[] = { I915_RESET_UEVENT "=1", NULL };
char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL };
- int ret;
kobject_uevent_env(kobj, KOBJ_CHANGE, error_event);
@@ -2512,24 +2511,30 @@
* simulated reset via debugs, so get an RPM reference.
*/
intel_runtime_pm_get(dev_priv);
-
intel_prepare_reset(dev_priv);
- /*
- * All state reset _must_ be completed before we update the
- * reset counter, for otherwise waiters might miss the reset
- * pending state and not properly drop locks, resulting in
- * deadlocks with the reset work.
- */
- mutex_lock(&dev_priv->drm.struct_mutex);
- ret = i915_reset(dev_priv);
- mutex_unlock(&dev_priv->drm.struct_mutex);
+ do {
+ /*
+ * All state reset _must_ be completed before we update the
+ * reset counter, for otherwise waiters might miss the reset
+ * pending state and not properly drop locks, resulting in
+ * deadlocks with the reset work.
+ */
+ if (mutex_trylock(&dev_priv->drm.struct_mutex)) {
+ i915_reset(dev_priv);
+ mutex_unlock(&dev_priv->drm.struct_mutex);
+ }
+
+ /* We need to wait for anyone holding the lock to wakeup */
+ } while (wait_on_bit_timeout(&dev_priv->gpu_error.flags,
+ I915_RESET_IN_PROGRESS,
+ TASK_UNINTERRUPTIBLE,
+ HZ));
intel_finish_reset(dev_priv);
-
intel_runtime_pm_put(dev_priv);
- if (ret == 0)
+ if (!test_bit(I915_WEDGED, &dev_priv->gpu_error.flags))
kobject_uevent_env(kobj,
KOBJ_CHANGE, reset_done_event);