4 files changed, 39 insertions, 46 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.c b/drivers/gpu/drm/i915/gt/intel_timeline.c
index d71aafb66d6e..ee5dc4fbdeb9 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline.c
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.c
@@ -15,6 +15,9 @@
 #define ptr_set_bit(ptr, bit) ((typeof(ptr))((unsigned long)(ptr) | BIT(bit)))
 #define ptr_test_bit(ptr, bit) ((unsigned long)(ptr) & BIT(bit))
 
+#define CACHELINE_BITS 6
+#define CACHELINE_FREE CACHELINE_BITS
+
 struct intel_timeline_hwsp {
 	struct intel_gt *gt;
 	struct intel_gt_timelines *gt_timelines;
@@ -23,14 +26,6 @@ struct intel_timeline_hwsp {
 	u64 free_bitmap;
 };
 
-struct intel_timeline_cacheline {
-	struct i915_active active;
-	struct intel_timeline_hwsp *hwsp;
-	void *vaddr;
-#define CACHELINE_BITS 6
-#define CACHELINE_FREE CACHELINE_BITS
-};
-
 static struct i915_vma *__hwsp_alloc(struct intel_gt *gt)
 {
 	struct drm_i915_private *i915 = gt->i915;
@@ -133,7 +128,7 @@ static void __idle_cacheline_free(struct intel_timeline_cacheline *cl)
 	__idle_hwsp_free(cl->hwsp, ptr_unmask_bits(cl->vaddr, CACHELINE_BITS));
 
 	i915_active_fini(&cl->active);
-	kfree(cl);
+	kfree_rcu(cl, rcu);
 }
 
 __i915_active_call
@@ -514,46 +509,35 @@ int intel_timeline_read_hwsp(struct i915_request *from,
 			     struct i915_request *to,
 			     u32 *hwsp)
 {
-	struct intel_timeline *tl;
+	struct intel_timeline_cacheline *cl;
 	int err;
 
+	GEM_BUG_ON(!rcu_access_pointer(from->hwsp_cacheline));
+
 	rcu_read_lock();
-	tl = rcu_dereference(from->timeline);
-	if (i915_request_completed(from) || !kref_get_unless_zero(&tl->kref))
-		tl = NULL;
+	cl = rcu_dereference(from->hwsp_cacheline);
+	if (unlikely(!i915_active_acquire_if_busy(&cl->active)))
+		goto unlock; /* seqno wrapped and completed! */
+	if (unlikely(i915_request_completed(from)))
+		goto release;
 	rcu_read_unlock();
-	if (!tl) /* already completed */
-		return 1;
 
-	GEM_BUG_ON(rcu_access_pointer(to->timeline) == tl);
-
-	err = -EAGAIN;
-	if (mutex_trylock(&tl->mutex)) {
-		struct intel_timeline_cacheline *cl = from->hwsp_cacheline;
-
-		if (i915_request_completed(from)) {
-			err = 1;
-			goto unlock;
-		}
+	err = cacheline_ref(cl, to);
+	if (err)
+		goto out;
 
-		err = cacheline_ref(cl, to);
-		if (err)
-			goto unlock;
+	*hwsp = i915_ggtt_offset(cl->hwsp->vma) +
+		ptr_unmask_bits(cl->vaddr, CACHELINE_BITS) * CACHELINE_BYTES;
 
-		if (likely(cl == tl->hwsp_cacheline)) {
-			*hwsp = tl->hwsp_offset;
-		} else { /* across a seqno wrap, recover the original offset */
-			*hwsp = i915_ggtt_offset(cl->hwsp->vma) +
-				ptr_unmask_bits(cl->vaddr, CACHELINE_BITS) *
-				CACHELINE_BYTES;
-		}
+out:
+	i915_active_release(&cl->active);
+	return err;
 
+release:
+	i915_active_release(&cl->active);
 unlock:
-		mutex_unlock(&tl->mutex);
-	}
-	intel_timeline_put(tl);
-
-	return err;
+	rcu_read_unlock();
+	return 1;
 }
 
 void intel_timeline_unpin(struct intel_timeline *tl)
diff --git a/drivers/gpu/drm/i915/gt/intel_timeline_types.h b/drivers/gpu/drm/i915/gt/intel_timeline_types.h
index aaf15cbe1ce1..24d040f14e89 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_timeline_types.h
@@ -10,14 +10,15 @@
 #include <linux/list.h>
 #include <linux/kref.h>
 #include <linux/mutex.h>
+#include <linux/rcupdate.h>
 #include <linux/types.h>
 
 #include "i915_active_types.h"
 
 struct drm_i915_private;
 struct i915_vma;
-struct intel_timeline_cacheline;
 struct i915_syncmap;
+struct intel_timeline_hwsp;
 
 struct intel_timeline {
 	u64 fence_context;
@@ -87,4 +88,13 @@ struct intel_timeline {
 	struct rcu_head rcu;
 };
 
+struct intel_timeline_cacheline {
+	struct i915_active active;
+
+	struct intel_timeline_hwsp *hwsp;
+	void *vaddr;
+
+	struct rcu_head rcu;
+};
+
 #endif /* __I915_TIMELINE_TYPES_H__ */
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index a59b803aef92..269470d3527a 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -655,9 +655,9 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
 	rq->execution_mask = ce->engine->mask;
 	rq->flags = 0;
 
-	rcu_assign_pointer(rq->timeline, tl);
+	RCU_INIT_POINTER(rq->timeline, tl);
+	RCU_INIT_POINTER(rq->hwsp_cacheline, tl->hwsp_cacheline);
 	rq->hwsp_seqno = tl->hwsp_seqno;
-	rq->hwsp_cacheline = tl->hwsp_cacheline;
 
 	rq->rcustate = get_state_synchronize_rcu(); /* acts as smp_mb() */
 
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index a561b8efe869..aa38290eea3d 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -30,6 +30,7 @@
 
 #include "gt/intel_context_types.h"
 #include "gt/intel_engine_types.h"
+#include "gt/intel_timeline_types.h"
 
 #include "i915_gem.h"
 #include "i915_scheduler.h"
@@ -41,8 +42,6 @@
 struct drm_file;
 struct drm_i915_gem_object;
 struct i915_request;
-struct intel_timeline;
-struct intel_timeline_cacheline;
 
 struct i915_capture_list {
 	struct i915_capture_list *next;
@@ -183,7 +182,7 @@ struct i915_request {
 	 * inside the timeline's HWSP vma, but it is only valid while this
 	 * request has not completed and guarded by the timeline mutex.
 	 */
-	struct intel_timeline_cacheline *hwsp_cacheline;
+	struct intel_timeline_cacheline __rcu *hwsp_cacheline;
 
 	/** Position in the ring of the start of the request */
 	u32 head;