As we need to use a mutex to serialisation i915_active activation
(because we want to allow the callback to sleep), we need to push the
i915_active.retire into a worker callback in case we get need to retire
from an atomic context.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_active.c | 54 ++++++++++++++++++------
drivers/gpu/drm/i915/i915_active_types.h | 3 ++
2 files changed, 44 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
index 6a9f8d37f415..f76a2b4ef95d 100644
--- a/drivers/gpu/drm/i915/i915_active.c
+++ b/drivers/gpu/drm/i915/i915_active.c
@@ -30,18 +30,14 @@ struct active_node {
};
static void
-active_retire(struct i915_active *ref)
+__active_retire(struct i915_active *ref)
{
struct active_node *it, *n;
struct rb_root root;
bool retire = false;
- GEM_BUG_ON(!atomic_read(&ref->count));
- if (atomic_add_unless(&ref->count, -1, 1))
- return;
-
- /* One active may be flushed from inside the acquire of another */
- mutex_lock_nested(&ref->mutex, SINGLE_DEPTH_NESTING);
+ lockdep_assert_held(&ref->mutex);
+ GEM_BUG_ON(i915_active_is_idle(ref));
/* return the unused nodes to our slabcache -- flushing the allocator */
if (atomic_dec_and_test(&ref->count)) {
@@ -63,6 +59,35 @@ active_retire(struct i915_active *ref)
}
}
+static void
+active_work(struct work_struct *wrk)
+{
+ struct i915_active *ref = container_of(wrk, typeof(*ref), work);
+
+ GEM_BUG_ON(!atomic_read(&ref->count));
+ if (atomic_add_unless(&ref->count, -1, 1))
+ return;
+
+ mutex_lock(&ref->mutex);
+ __active_retire(ref);
+}
+
+static void
+active_retire(struct i915_active *ref)
+{
+ GEM_BUG_ON(!atomic_read(&ref->count));
+ if (atomic_add_unless(&ref->count, -1, 1))
+ return;
+
+ /* If we are inside interrupt context (fence signaling), defer */
+ if (!mutex_trylock(&ref->mutex)) {
+ queue_work(system_unbound_wq, &ref->work);
+ return;
+ }
+
+ __active_retire(ref);
+}
+
static void
node_retire(struct i915_active_request *base, struct i915_request *rq)
{
@@ -140,6 +165,7 @@ void __i915_active_init(struct drm_i915_private *i915,
init_llist_head(&ref->barriers);
atomic_set(&ref->count, 0);
__mutex_init(&ref->mutex, "i915_active", key);
+ INIT_WORK(&ref->work, active_work);
}
int i915_active_ref(struct i915_active *ref,
@@ -208,8 +234,10 @@ int i915_active_wait(struct i915_active *ref)
if (err)
return err;
- if (!atomic_add_unless(&ref->count, 1, 0))
- goto unlock;
+ if (!atomic_add_unless(&ref->count, 1, 0)) {
+ mutex_unlock(&ref->mutex);
+ return 0;
+ }
rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
err = i915_active_request_retire(&it->base, BKL(ref));
@@ -217,9 +245,8 @@ int i915_active_wait(struct i915_active *ref)
break;
}
- active_retire(ref);
-unlock:
- mutex_unlock(&ref->mutex);
+ __active_retire(ref);
+ flush_work(&ref->work);
return err;
}
@@ -260,8 +287,9 @@ int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
void i915_active_fini(struct i915_active *ref)
{
- GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
GEM_BUG_ON(atomic_read(&ref->count));
+ GEM_BUG_ON(work_pending(&ref->work));
+ GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
mutex_destroy(&ref->mutex);
}
#endif
diff --git a/drivers/gpu/drm/i915/i915_active_types.h b/drivers/gpu/drm/i915/i915_active_types.h
index 5b0a3024ce24..06acdffe0f6d 100644
--- a/drivers/gpu/drm/i915/i915_active_types.h
+++ b/drivers/gpu/drm/i915/i915_active_types.h
@@ -12,6 +12,7 @@
#include <linux/mutex.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.h>
+#include <linux/workqueue.h>
struct drm_i915_private;
struct i915_active_request;
@@ -39,6 +40,8 @@ struct i915_active {
int (*active)(struct i915_active *ref);
void (*retire)(struct i915_active *ref);
+ struct work_struct work;
+
struct llist_head barriers;
};
--
2.20.1
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