Commit 3b19f16a authored by Chris Wilson's avatar Chris Wilson

drm/i915: Drain the device workqueue on unload

Workers on the i915->wq may rearm themselves so for completeness we need
to replace our flush_workqueue() with a call to drain_workqueue() before
unloading the device.

v2: Reinforce the drain_workqueue with an preceding rcu_barrier() as a
few of the tasks that need to be drained may first be armed by RCU.

References: https://bugs.freedesktop.org/show_bug.cgi?id=101627Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170718134124.14832-1-chris@chris-wilson.co.ukReviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
parent 023f8079
......@@ -596,7 +596,8 @@ static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
static void i915_gem_fini(struct drm_i915_private *dev_priv)
{
flush_workqueue(dev_priv->wq);
/* Flush any outstanding unpin_work. */
i915_gem_drain_workqueue(dev_priv);
mutex_lock(&dev_priv->drm.struct_mutex);
intel_uc_fini_hw(dev_priv);
......@@ -1413,9 +1414,6 @@ void i915_driver_unload(struct drm_device *dev)
cancel_delayed_work_sync(&dev_priv->gpu_error.hangcheck_work);
i915_reset_error_state(dev_priv);
/* Flush any outstanding unpin_work. */
drain_workqueue(dev_priv->wq);
i915_gem_fini(dev_priv);
intel_uc_fini_fw(dev_priv);
intel_fbc_cleanup_cfb(dev_priv);
......
......@@ -3300,6 +3300,26 @@ static inline void i915_gem_drain_freed_objects(struct drm_i915_private *i915)
} while (flush_work(&i915->mm.free_work));
}
static inline void i915_gem_drain_workqueue(struct drm_i915_private *i915)
{
/*
* Similar to objects above (see i915_gem_drain_freed-objects), in
* general we have workers that are armed by RCU and then rearm
* themselves in their callbacks. To be paranoid, we need to
* drain the workqueue a second time after waiting for the RCU
* grace period so that we catch work queued via RCU from the first
* pass. As neither drain_workqueue() nor flush_workqueue() report
* a result, we make an assumption that we only don't require more
* than 2 passes to catch all recursive RCU delayed work.
*
*/
int pass = 2;
do {
rcu_barrier();
drain_workqueue(i915->wq);
} while (--pass);
}
struct i915_vma * __must_check
i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
const struct i915_ggtt_view *view,
......
......@@ -57,7 +57,7 @@ static void mock_device_release(struct drm_device *dev)
cancel_delayed_work_sync(&i915->gt.retire_work);
cancel_delayed_work_sync(&i915->gt.idle_work);
flush_workqueue(i915->wq);
i915_gem_drain_workqueue(i915);
mutex_lock(&i915->drm.struct_mutex);
for_each_engine(engine, i915, id)
......
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