[PATCH 04/24] drm/i915: Add an implementation for i915_gem_ww_ctx locking, v2.

Maarten Lankhorst maarten.lankhorst at linux.intel.com
Tue Apr 21 10:33:49 UTC 2020


i915_gem_ww_ctx is used to lock all gem bo's for pinning and memory
eviction. We don't use it yet, but lets start adding the definition
first.

To use it, we have to pass a non-NULL ww to gem_object_lock, and don't
unlock directly. It is done in i915_gem_ww_ctx_fini.

Changes since v1:
- Change ww_ctx and obj order in locking functions (Jonas Lahtinen)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c  |  4 +-
 .../gpu/drm/i915/gem/i915_gem_client_blt.c    |  2 +-
 drivers/gpu/drm/i915/gem/i915_gem_context.c   |  2 +-
 drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c    |  4 +-
 drivers/gpu/drm/i915/gem/i915_gem_domain.c    | 10 ++--
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |  4 +-
 drivers/gpu/drm/i915/gem/i915_gem_object.c    |  2 +-
 drivers/gpu/drm/i915/gem/i915_gem_object.h    | 38 +++++++++++---
 .../gpu/drm/i915/gem/i915_gem_object_blt.c    |  2 +-
 .../gpu/drm/i915/gem/i915_gem_object_types.h  |  9 ++++
 drivers/gpu/drm/i915/gem/i915_gem_pm.c        |  2 +-
 drivers/gpu/drm/i915/gem/i915_gem_tiling.c    |  2 +-
 .../gpu/drm/i915/gem/selftests/huge_pages.c   |  2 +-
 .../i915/gem/selftests/i915_gem_client_blt.c  |  2 +-
 .../i915/gem/selftests/i915_gem_coherency.c   | 10 ++--
 .../drm/i915/gem/selftests/i915_gem_context.c |  4 +-
 .../drm/i915/gem/selftests/i915_gem_mman.c    |  4 +-
 .../drm/i915/gem/selftests/i915_gem_phys.c    |  2 +-
 drivers/gpu/drm/i915/gt/intel_gt.c            |  2 +-
 .../gpu/drm/i915/gt/selftest_workarounds.c    |  2 +-
 drivers/gpu/drm/i915/gvt/cmd_parser.c         |  2 +-
 drivers/gpu/drm/i915/i915_gem.c               | 52 +++++++++++++++++--
 drivers/gpu/drm/i915/i915_gem.h               | 11 ++++
 drivers/gpu/drm/i915/selftests/i915_gem.c     | 41 +++++++++++++++
 drivers/gpu/drm/i915/selftests/i915_vma.c     |  2 +-
 .../drm/i915/selftests/intel_memory_region.c  |  2 +-
 26 files changed, 175 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index adb08a00bb57..1064e34e42cd 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -2309,7 +2309,7 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
 
 void intel_unpin_fb_vma(struct i915_vma *vma, unsigned long flags)
 {
-	i915_gem_object_lock(vma->obj);
+	i915_gem_object_lock(vma->obj, NULL);
 	if (flags & PLANE_HAS_FENCE)
 		i915_vma_unpin_fence(vma);
 	i915_gem_object_unpin_from_display_plane(vma);
@@ -16958,7 +16958,7 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb,
 	if (!intel_fb->frontbuffer)
 		return -ENOMEM;
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	tiling = i915_gem_object_get_tiling(obj);
 	stride = i915_gem_object_get_stride(obj);
 	i915_gem_object_unlock(obj);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c
index 3a146aa2593b..2f1d8150256b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_client_blt.c
@@ -286,7 +286,7 @@ int i915_gem_schedule_fill_pages_blt(struct drm_i915_gem_object *obj,
 	dma_fence_init(&work->dma, &clear_pages_work_ops, &fence_lock, 0, 0);
 	i915_sw_fence_init(&work->wait, clear_pages_work_notify);
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_sw_fence_await_reservation(&work->wait,
 					      obj->base.resv, NULL,
 					      true, I915_FENCE_TIMEOUT,
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 11d9135cf21a..022716f05e91 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -113,7 +113,7 @@ static void lut_close(struct i915_gem_context *ctx)
 			continue;
 
 		rcu_read_unlock();
-		i915_gem_object_lock(obj);
+		i915_gem_object_lock(obj, NULL);
 		list_for_each_entry(lut, &obj->lut_list, obj_link) {
 			if (lut->ctx != ctx)
 				continue;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 7db5a793739d..cfadccfc2990 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -128,7 +128,7 @@ static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_dire
 	if (err)
 		return err;
 
-	err = i915_gem_object_lock_interruptible(obj);
+	err = i915_gem_object_lock_interruptible(obj, NULL);
 	if (err)
 		goto out;
 
@@ -149,7 +149,7 @@ static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direct
 	if (err)
 		return err;
 
-	err = i915_gem_object_lock_interruptible(obj);
+	err = i915_gem_object_lock_interruptible(obj, NULL);
 	if (err)
 		goto out;
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index 7f76fc68f498..c0acfc97fae3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -32,7 +32,7 @@ void i915_gem_object_flush_if_display(struct drm_i915_gem_object *obj)
 	if (!i915_gem_object_is_framebuffer(obj))
 		return;
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	__i915_gem_object_flush_for_display(obj);
 	i915_gem_object_unlock(obj);
 }
@@ -197,7 +197,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 	if (ret)
 		return ret;
 
-	ret = i915_gem_object_lock_interruptible(obj);
+	ret = i915_gem_object_lock_interruptible(obj, NULL);
 	if (ret)
 		return ret;
 
@@ -536,7 +536,7 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
 	if (err)
 		goto out;
 
-	err = i915_gem_object_lock_interruptible(obj);
+	err = i915_gem_object_lock_interruptible(obj, NULL);
 	if (err)
 		goto out_unpin;
 
@@ -576,7 +576,7 @@ int i915_gem_object_prepare_read(struct drm_i915_gem_object *obj,
 	if (!i915_gem_object_has_struct_page(obj))
 		return -ENODEV;
 
-	ret = i915_gem_object_lock_interruptible(obj);
+	ret = i915_gem_object_lock_interruptible(obj, NULL);
 	if (ret)
 		return ret;
 
@@ -630,7 +630,7 @@ int i915_gem_object_prepare_write(struct drm_i915_gem_object *obj,
 	if (!i915_gem_object_has_struct_page(obj))
 		return -ENODEV;
 
-	ret = i915_gem_object_lock_interruptible(obj);
+	ret = i915_gem_object_lock_interruptible(obj, NULL);
 	if (ret)
 		return ret;
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 40a6bc89c2b8..bc5371d8da0a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -813,7 +813,7 @@ static int __eb_add_lut(struct i915_execbuffer *eb,
 		if (err == 0) { /* And nor has this handle */
 			struct drm_i915_gem_object *obj = vma->obj;
 
-			i915_gem_object_lock(obj);
+			i915_gem_object_lock(obj, NULL);
 			if (idr_find(&eb->file->object_idr, handle) == obj) {
 				list_add(&lut->obj_link, &obj->lut_list);
 			} else {
@@ -1083,7 +1083,7 @@ static void *reloc_iomap(struct drm_i915_gem_object *obj,
 		if (use_cpu_reloc(cache, obj))
 			return NULL;
 
-		i915_gem_object_lock(obj);
+		i915_gem_object_lock(obj, NULL);
 		err = i915_gem_object_set_to_gtt_domain(obj, true);
 		i915_gem_object_unlock(obj);
 		if (err)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 3f01cdd1a39b..cf7661afd640 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -104,7 +104,7 @@ void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
 	struct i915_lut_handle *lut, *ln;
 	LIST_HEAD(close);
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	list_for_each_entry_safe(lut, ln, &obj->lut_list, obj_link) {
 		struct i915_gem_context *ctx = lut->ctx;
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 2faa481cc18f..5103067269b0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -110,20 +110,44 @@ i915_gem_object_put(struct drm_i915_gem_object *obj)
 
 #define assert_object_held(obj) dma_resv_assert_held((obj)->base.resv)
 
-static inline void i915_gem_object_lock(struct drm_i915_gem_object *obj)
+static inline int __i915_gem_object_lock(struct drm_i915_gem_object *obj,
+					 struct i915_gem_ww_ctx *ww,
+					 bool intr)
 {
-	dma_resv_lock(obj->base.resv, NULL);
+	int ret;
+
+	if (intr)
+		ret = dma_resv_lock_interruptible(obj->base.resv, ww ? &ww->ctx : NULL);
+	else
+		ret = dma_resv_lock(obj->base.resv, ww ? &ww->ctx : NULL);
+
+	if (!ret && ww)
+		list_add_tail(&obj->obj_link, &ww->obj_list);
+	if (ret == -EALREADY)
+		ret = 0;
+
+	if (ret == -EDEADLK)
+		ww->contended = obj;
+
+	return ret;
 }
 
-static inline bool i915_gem_object_trylock(struct drm_i915_gem_object *obj)
+static inline int i915_gem_object_lock(struct drm_i915_gem_object *obj,
+				       struct i915_gem_ww_ctx *ww)
 {
-	return dma_resv_trylock(obj->base.resv);
+	return __i915_gem_object_lock(obj, ww, ww && ww->intr);
 }
 
-static inline int
-i915_gem_object_lock_interruptible(struct drm_i915_gem_object *obj)
+static inline int i915_gem_object_lock_interruptible(struct drm_i915_gem_object *obj,
+						     struct i915_gem_ww_ctx *ww)
 {
-	return dma_resv_lock_interruptible(obj->base.resv, NULL);
+	WARN_ON(ww && !ww->intr);
+	return __i915_gem_object_lock(obj, ww, true);
+}
+
+static inline bool i915_gem_object_trylock(struct drm_i915_gem_object *obj)
+{
+	return dma_resv_trylock(obj->base.resv);
 }
 
 static inline void i915_gem_object_unlock(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c b/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c
index 2fc7737ef5f4..8e7b6a1efd0c 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_blt.c
@@ -142,7 +142,7 @@ int i915_gem_object_fill_blt(struct drm_i915_gem_object *obj,
 		return err;
 
 	if (obj->cache_dirty & ~obj->cache_coherent) {
-		i915_gem_object_lock(obj);
+		i915_gem_object_lock(obj, NULL);
 		i915_gem_clflush_object(obj, 0);
 		i915_gem_object_unlock(obj);
 	}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 54ee658bb168..80951e35f86f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -120,6 +120,15 @@ struct drm_i915_gem_object {
 	 */
 	struct list_head lut_list;
 
+	/**
+	 * @obj_link: Link into @i915_gem_ww_ctx.obj_list
+	 *
+	 * When we lock this object through i915_gem_object_lock() with a
+	 * context, we add it to the list to ensure we can unlock everything
+	 * when i915_gem_ww_ctx_backoff() or i915_gem_ww_ctx_fini() are called.
+	 */
+	struct list_head obj_link;
+
 	/** Stolen memory for this object, instead of being backed by shmem. */
 	struct drm_mm_node *stolen;
 	union {
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pm.c b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
index 3d215164dd5a..40d3e40500fa 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
@@ -84,7 +84,7 @@ void i915_gem_suspend_late(struct drm_i915_private *i915)
 
 			spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
 
-			i915_gem_object_lock(obj);
+			i915_gem_object_lock(obj, NULL);
 			drm_WARN_ON(&i915->drm,
 			    i915_gem_object_set_to_gtt_domain(obj, false));
 			i915_gem_object_unlock(obj);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
index 37f77aee1212..676aca5180d5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_tiling.c
@@ -235,7 +235,7 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
 	 * whilst executing a fenced command for an untiled object.
 	 */
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	if (i915_gem_object_is_framebuffer(obj)) {
 		i915_gem_object_unlock(obj);
 		return -EBUSY;
diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
index d4f94ca9ae0d..8f7d7a06b5bb 100644
--- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
@@ -974,7 +974,7 @@ static int gpu_write(struct intel_context *ce,
 {
 	int err;
 
-	i915_gem_object_lock(vma->obj);
+	i915_gem_object_lock(vma->obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(vma->obj, true);
 	i915_gem_object_unlock(vma->obj);
 	if (err)
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
index b972be165e85..a4bf026b2988 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
@@ -72,7 +72,7 @@ static int __igt_client_fill(struct intel_engine_cs *engine)
 		if (err)
 			goto err_unpin;
 
-		i915_gem_object_lock(obj);
+		i915_gem_object_lock(obj, NULL);
 		err = i915_gem_object_set_to_cpu_domain(obj, false);
 		i915_gem_object_unlock(obj);
 		if (err)
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
index 3f6079e1dfb6..f5a0c7b1e113 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
@@ -82,7 +82,7 @@ static int gtt_set(struct context *ctx, unsigned long offset, u32 v)
 	u32 __iomem *map;
 	int err = 0;
 
-	i915_gem_object_lock(ctx->obj);
+	i915_gem_object_lock(ctx->obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
 	i915_gem_object_unlock(ctx->obj);
 	if (err)
@@ -115,7 +115,7 @@ static int gtt_get(struct context *ctx, unsigned long offset, u32 *v)
 	u32 __iomem *map;
 	int err = 0;
 
-	i915_gem_object_lock(ctx->obj);
+	i915_gem_object_lock(ctx->obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(ctx->obj, false);
 	i915_gem_object_unlock(ctx->obj);
 	if (err)
@@ -147,7 +147,7 @@ static int wc_set(struct context *ctx, unsigned long offset, u32 v)
 	u32 *map;
 	int err;
 
-	i915_gem_object_lock(ctx->obj);
+	i915_gem_object_lock(ctx->obj, NULL);
 	err = i915_gem_object_set_to_wc_domain(ctx->obj, true);
 	i915_gem_object_unlock(ctx->obj);
 	if (err)
@@ -168,7 +168,7 @@ static int wc_get(struct context *ctx, unsigned long offset, u32 *v)
 	u32 *map;
 	int err;
 
-	i915_gem_object_lock(ctx->obj);
+	i915_gem_object_lock(ctx->obj, NULL);
 	err = i915_gem_object_set_to_wc_domain(ctx->obj, false);
 	i915_gem_object_unlock(ctx->obj);
 	if (err)
@@ -191,7 +191,7 @@ static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
 	u32 *cs;
 	int err;
 
-	i915_gem_object_lock(ctx->obj);
+	i915_gem_object_lock(ctx->obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
 	i915_gem_object_unlock(ctx->obj);
 	if (err)
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
index f4f933240b39..265096de05ca 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
@@ -950,7 +950,7 @@ emit_rpcs_query(struct drm_i915_gem_object *obj,
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(obj, false);
 	i915_gem_object_unlock(obj);
 	if (err)
@@ -1691,7 +1691,7 @@ static int read_from_scratch(struct i915_gem_context *ctx,
 
 	i915_request_add(rq);
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_set_to_cpu_domain(obj, false);
 	i915_gem_object_unlock(obj);
 	if (err)
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
index ef7abcb3f4ee..eec58da734bd 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
@@ -103,7 +103,7 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj,
 	GEM_BUG_ON(i915_gem_object_get_tiling(obj) != tile->tiling);
 	GEM_BUG_ON(i915_gem_object_get_stride(obj) != tile->stride);
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(obj, true);
 	i915_gem_object_unlock(obj);
 	if (err) {
@@ -188,7 +188,7 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj,
 	GEM_BUG_ON(i915_gem_object_get_tiling(obj) != tile->tiling);
 	GEM_BUG_ON(i915_gem_object_get_stride(obj) != tile->stride);
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(obj, true);
 	i915_gem_object_unlock(obj);
 	if (err) {
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c
index 34932871b3a5..a94243dc4c5c 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_phys.c
@@ -44,7 +44,7 @@ static int mock_phys_object(void *arg)
 	}
 
 	/* Make the object dirty so that put_pages must do copy back the data */
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(obj, true);
 	i915_gem_object_unlock(obj);
 	if (err) {
diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
index 8ae37ea38389..342a9558751c 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -487,7 +487,7 @@ static int __engines_record_defaults(struct intel_gt *gt)
 		if (err)
 			goto out;
 
-		i915_gem_object_lock(state->obj);
+		i915_gem_object_lock(state->obj, NULL);
 		err = i915_gem_object_set_to_cpu_domain(state->obj, false);
 		i915_gem_object_unlock(state->obj);
 		if (err)
diff --git a/drivers/gpu/drm/i915/gt/selftest_workarounds.c b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
index 5ed323254ee1..282f51feacd5 100644
--- a/drivers/gpu/drm/i915/gt/selftest_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/selftest_workarounds.c
@@ -214,7 +214,7 @@ static int check_whitelist(struct i915_gem_context *ctx,
 		return PTR_ERR(results);
 
 	err = 0;
-	i915_gem_object_lock(results);
+	i915_gem_object_lock(results, NULL);
 	intel_wedge_on_timeout(&wedge, engine->gt, HZ / 5) /* safety net! */
 		err = i915_gem_object_set_to_cpu_domain(results, false);
 	i915_gem_object_unlock(results);
diff --git a/drivers/gpu/drm/i915/gvt/cmd_parser.c b/drivers/gpu/drm/i915/gvt/cmd_parser.c
index a3cc080a46c6..cb91e9e097a7 100644
--- a/drivers/gpu/drm/i915/gvt/cmd_parser.c
+++ b/drivers/gpu/drm/i915/gvt/cmd_parser.c
@@ -2949,7 +2949,7 @@ static int shadow_indirect_ctx(struct intel_shadow_wa_ctx *wa_ctx)
 		goto put_obj;
 	}
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	ret = i915_gem_object_set_to_cpu_domain(obj, false);
 	i915_gem_object_unlock(obj);
 	if (ret) {
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0cbcb9f54e7d..3eedd4e0ebab 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -420,7 +420,7 @@ i915_gem_gtt_pread(struct drm_i915_gem_object *obj,
 		GEM_BUG_ON(!drm_mm_node_allocated(&node));
 	}
 
-	ret = i915_gem_object_lock_interruptible(obj);
+	ret = i915_gem_object_lock_interruptible(obj, NULL);
 	if (ret)
 		goto out_unpin;
 
@@ -619,7 +619,7 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
 		GEM_BUG_ON(!drm_mm_node_allocated(&node));
 	}
 
-	ret = i915_gem_object_lock_interruptible(obj);
+	ret = i915_gem_object_lock_interruptible(obj, NULL);
 	if (ret)
 		goto out_unpin;
 
@@ -1272,7 +1272,7 @@ int i915_gem_freeze_late(struct drm_i915_private *i915)
 	i915_gem_drain_freed_objects(i915);
 
 	list_for_each_entry(obj, &i915->mm.shrink_list, mm.link) {
-		i915_gem_object_lock(obj);
+		i915_gem_object_lock(obj, NULL);
 		drm_WARN_ON(&i915->drm,
 			    i915_gem_object_set_to_cpu_domain(obj, true));
 		i915_gem_object_unlock(obj);
@@ -1326,6 +1326,52 @@ int i915_gem_open(struct drm_i915_private *i915, struct drm_file *file)
 	return ret;
 }
 
+void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ww, bool intr)
+{
+	ww_acquire_init(&ww->ctx, &reservation_ww_class);
+	INIT_LIST_HEAD(&ww->obj_list);
+	ww->intr = intr;
+	ww->contended = NULL;
+}
+
+static void i915_gem_ww_ctx_unlock_all(struct i915_gem_ww_ctx *ww)
+{
+	struct drm_i915_gem_object *obj;
+
+	while ((obj = list_first_entry_or_null(&ww->obj_list, struct drm_i915_gem_object, obj_link))) {
+		list_del(&obj->obj_link);
+		i915_gem_object_unlock(obj);
+	}
+}
+
+void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ww)
+{
+	i915_gem_ww_ctx_unlock_all(ww);
+	WARN_ON(ww->contended);
+	ww_acquire_fini(&ww->ctx);
+}
+
+int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ww)
+{
+	int ret = 0;
+
+	if (WARN_ON(!ww->contended))
+		return -EINVAL;
+
+	i915_gem_ww_ctx_unlock_all(ww);
+	if (ww->intr)
+		ret = dma_resv_lock_slow_interruptible(ww->contended->base.resv, &ww->ctx);
+	else
+		dma_resv_lock_slow(ww->contended->base.resv, &ww->ctx);
+
+	if (!ret)
+		list_add_tail(&ww->contended->obj_link, &ww->obj_list);
+
+	ww->contended = NULL;
+
+	return ret;
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_gem_device.c"
 #include "selftests/i915_gem.c"
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index 1753c84d6c0d..988755dbf4be 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -116,4 +116,15 @@ static inline bool __tasklet_is_scheduled(struct tasklet_struct *t)
 	return test_bit(TASKLET_STATE_SCHED, &t->state);
 }
 
+struct i915_gem_ww_ctx {
+	struct ww_acquire_ctx ctx;
+	struct list_head obj_list;
+	bool intr;
+	struct drm_i915_gem_object *contended;
+};
+
+void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ctx, bool intr);
+void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ctx);
+int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ctx);
+
 #endif /* __I915_GEM_H__ */
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem.c b/drivers/gpu/drm/i915/selftests/i915_gem.c
index 88d400b9df88..23a6132c5f4e 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem.c
@@ -199,11 +199,52 @@ static int igt_gem_hibernate(void *arg)
 	return err;
 }
 
+static int igt_gem_ww_ctx(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct drm_i915_gem_object *obj, *obj2;
+	struct i915_gem_ww_ctx ww;
+	int err = 0;
+
+	obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
+	if (IS_ERR(obj))
+		return PTR_ERR(obj);
+
+	obj2 = i915_gem_object_create_internal(i915, PAGE_SIZE);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto put1;
+	}
+
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	/* Lock the objects, twice for good measure (-EALREADY handling) */
+	err = i915_gem_object_lock(obj, &ww);
+	if (!err)
+		err = i915_gem_object_lock_interruptible(obj, &ww);
+	if (!err)
+		err = i915_gem_object_lock_interruptible(obj2, &ww);
+	if (!err)
+		err = i915_gem_object_lock(obj2, &ww);
+
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
+	i915_gem_object_put(obj2);
+put1:
+	i915_gem_object_put(obj);
+	return err;
+}
+
 int i915_gem_live_selftests(struct drm_i915_private *i915)
 {
 	static const struct i915_subtest tests[] = {
 		SUBTEST(igt_gem_suspend),
 		SUBTEST(igt_gem_hibernate),
+		SUBTEST(igt_gem_ww_ctx),
 	};
 
 	if (intel_gt_is_wedged(&i915->gt))
diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c b/drivers/gpu/drm/i915/selftests/i915_vma.c
index 58b5f40a07dd..9bc00c724b0e 100644
--- a/drivers/gpu/drm/i915/selftests/i915_vma.c
+++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
@@ -892,7 +892,7 @@ static int igt_vma_remapped_gtt(void *arg)
 			unsigned int x, y;
 			int err;
 
-			i915_gem_object_lock(obj);
+			i915_gem_object_lock(obj, NULL);
 			err = i915_gem_object_set_to_gtt_domain(obj, true);
 			i915_gem_object_unlock(obj);
 			if (err)
diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
index 6e80d99048e4..957a7a52def7 100644
--- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
@@ -509,7 +509,7 @@ static int igt_lmem_write_cpu(void *arg)
 	if (err)
 		goto out_unpin;
 
-	i915_gem_object_lock(obj);
+	i915_gem_object_lock(obj, NULL);
 	err = i915_gem_object_set_to_wc_domain(obj, true);
 	i915_gem_object_unlock(obj);
 	if (err)
-- 
2.26.1



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