[RFC,034/162] drm/i915: Take reservation lock around i915_vma_pin.

Commit Message

Matthew Auld Nov. 27, 2020, 12:05 p.m. UTC

From: Maarten Lankhorst <[e-mail]>

We previously complained when ww == NULL.

This function is now only used in selftests to pin an object,
and ww locking is now fixed.

Signed-off-by: Maarten Lankhorst <[e-mail]>
Cc: Thomas Hellström <[e-mail]>
---
 .../i915/gem/selftests/i915_gem_coherency.c   | 14 +++++--------
 drivers/gpu/drm/i915/i915_gem.c               |  6 +++++-
 drivers/gpu/drm/i915/i915_vma.c               |  3 +--
 drivers/gpu/drm/i915/i915_vma.h               | 20 +++++++++++++++----
 4 files changed, 27 insertions(+), 16 deletions(-)

Patch

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 7049a6bbc03d..2e439bb269d6 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
@@ -199,16 +199,14 @@  static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
 	u32 *cs;
 	int err;
 
+	vma = i915_gem_object_ggtt_pin(ctx->obj, NULL, 0, 0, 0);
+	if (IS_ERR(vma))
+		return PTR_ERR(vma);
+
 	i915_gem_object_lock(ctx->obj, NULL);
 	err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
 	if (err)
-		goto out_unlock;
-
-	vma = i915_gem_object_ggtt_pin(ctx->obj, NULL, 0, 0, 0);
-	if (IS_ERR(vma)) {
-		err = PTR_ERR(vma);
-		goto out_unlock;
-	}
+		goto out_unpin;
 
 	rq = intel_engine_create_kernel_request(ctx->engine);
 	if (IS_ERR(rq)) {
@@ -248,9 +246,7 @@  static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
 	i915_request_add(rq);
 out_unpin:
 	i915_vma_unpin(vma);
-out_unlock:
 	i915_gem_object_unlock(ctx->obj);
-
 	return err;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0b9eab66511c..b5311f7ad870 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1011,7 +1011,11 @@  i915_gem_object_ggtt_pin_ww(struct drm_i915_gem_object *obj,
 			return ERR_PTR(ret);
 	}
 
-	ret = i915_vma_pin_ww(vma, ww, size, alignment, flags | PIN_GLOBAL);
+	if (ww)
+		ret = i915_vma_pin_ww(vma, ww, size, alignment, flags | PIN_GLOBAL);
+	else
+		ret = i915_vma_pin(vma, size, alignment, flags | PIN_GLOBAL);
+
 	if (ret)
 		return ERR_PTR(ret);
 
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 5b1d78fa748e..63bdb0cc981e 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -868,8 +868,7 @@  int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
 			vma->obj && i915_gem_object_has_pinned_pages(vma->obj) &&
 			!vma->vm->allocate_va_range;
 
-		if (lockdep_is_held(&vma->vm->i915->drm.struct_mutex) &&
-		    !pinned_bind_wo_alloc)
+		if (!pinned_bind_wo_alloc)
 			WARN_ON(!ww);
 		if (ww && vma->resv)
 			assert_vma_held(vma);
diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index a2e7b58b70ca..2db4f25b8d5f 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -246,10 +246,22 @@  i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
 static inline int __must_check
 i915_vma_pin(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 {
-#ifdef CONFIG_LOCKDEP
-	WARN_ON_ONCE(vma->resv && dma_resv_held(vma->resv));
-#endif
-	return i915_vma_pin_ww(vma, NULL, size, alignment, flags);
+	struct i915_gem_ww_ctx ww;
+	int err;
+
+	i915_gem_ww_ctx_init(&ww, true);
+retry:
+	err = i915_gem_object_lock(vma->obj, &ww);
+	if (!err)
+		err = i915_vma_pin_ww(vma, &ww, size, alignment, flags);
+	if (err == -EDEADLK) {
+		err = i915_gem_ww_ctx_backoff(&ww);
+		if (!err)
+			goto retry;
+	}
+	i915_gem_ww_ctx_fini(&ww);
+
+	return err;
 }
 
 int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,