drm/i915: Break out the i915_deps utility

Since it's starting to be used outside the i915 TTM move code, move it
to a separate set of files.

v2:
- Update the documentation.
v4:
- Rebase.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211221200050.436316-4-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/i915/Makefile

@@ -163,6 +163,7 @@ i915-y += \
 	  i915_active.o \
 	  i915_buddy.o \
 	  i915_cmd_parser.o \
+	  i915_deps.o \
 	  i915_gem_evict.o \
 	  i915_gem_gtt.o \
 	  i915_gem_ww.o \

drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c

@@ -5,6 +5,7 @@
 
 #include <drm/ttm/ttm_bo_driver.h>
 
+#include "i915_deps.h"
 #include "i915_drv.h"
 #include "intel_memory_region.h"
 #include "intel_region_ttm.h"
@@ -41,176 +42,6 @@ void i915_ttm_migrate_set_failure_modes(bool gpu_migration,
 }
 #endif
 
-/**
- * DOC: Set of utilities to dynamically collect dependencies into a
- * structure which is fed into the GT migration code.
- *
- * Once we can do async unbinding, this is also needed to coalesce
- * the migration fence with the unbind fences if these are coalesced
- * post-migration.
- *
- * While collecting the individual dependencies, we store the refcounted
- * struct dma_fence pointers in a realloc-managed pointer array, since
- * that can be easily fed into a dma_fence_array. Other options are
- * available, like for example an xarray for similarity with drm/sched.
- * Can be changed easily if needed.
- *
- * A struct i915_deps need to be initialized using i915_deps_init().
- * If i915_deps_add_dependency() or i915_deps_add_resv() return an
- * error code they will internally call i915_deps_fini(), which frees
- * all internal references and allocations.
- *
- * We might want to break this out into a separate file as a utility.
- */
-
-#define I915_DEPS_MIN_ALLOC_CHUNK 8U
-
-static void i915_deps_reset_fences(struct i915_deps *deps)
-{
-	if (deps->fences != &deps->single)
-		kfree(deps->fences);
-	deps->num_deps = 0;
-	deps->fences_size = 1;
-	deps->fences = &deps->single;
-}
-
-static void i915_deps_init(struct i915_deps *deps, gfp_t gfp)
-{
-	deps->fences = NULL;
-	deps->gfp = gfp;
-	i915_deps_reset_fences(deps);
-}
-
-static void i915_deps_fini(struct i915_deps *deps)
-{
-	unsigned int i;
-
-	for (i = 0; i < deps->num_deps; ++i)
-		dma_fence_put(deps->fences[i]);
-
-	if (deps->fences != &deps->single)
-		kfree(deps->fences);
-}
-
-static int i915_deps_grow(struct i915_deps *deps, struct dma_fence *fence,
-			  const struct ttm_operation_ctx *ctx)
-{
-	int ret;
-
-	if (deps->num_deps >= deps->fences_size) {
-		unsigned int new_size = 2 * deps->fences_size;
-		struct dma_fence **new_fences;
-
-		new_size = max(new_size, I915_DEPS_MIN_ALLOC_CHUNK);
-		new_fences = kmalloc_array(new_size, sizeof(*new_fences), deps->gfp);
-		if (!new_fences)
-			goto sync;
-
-		memcpy(new_fences, deps->fences,
-		       deps->fences_size * sizeof(*new_fences));
-		swap(new_fences, deps->fences);
-		if (new_fences != &deps->single)
-			kfree(new_fences);
-		deps->fences_size = new_size;
-	}
-	deps->fences[deps->num_deps++] = dma_fence_get(fence);
-	return 0;
-
-sync:
-	if (ctx->no_wait_gpu && !dma_fence_is_signaled(fence)) {
-		ret = -EBUSY;
-		goto unref;
-	}
-
-	ret = dma_fence_wait(fence, ctx->interruptible);
-	if (ret)
-		goto unref;
-
-	ret = fence->error;
-	if (ret)
-		goto unref;
-
-	return 0;
-
-unref:
-	i915_deps_fini(deps);
-	return ret;
-}
-
-static int i915_deps_sync(const struct i915_deps *deps,
-			  const struct ttm_operation_ctx *ctx)
-{
-	struct dma_fence **fences = deps->fences;
-	unsigned int i;
-	int ret = 0;
-
-	for (i = 0; i < deps->num_deps; ++i, ++fences) {
-		if (ctx->no_wait_gpu && !dma_fence_is_signaled(*fences)) {
-			ret = -EBUSY;
-			break;
-		}
-
-		ret = dma_fence_wait(*fences, ctx->interruptible);
-		if (!ret)
-			ret = (*fences)->error;
-		if (ret)
-			break;
-	}
-
-	return ret;
-}
-
-static int i915_deps_add_dependency(struct i915_deps *deps,
-				    struct dma_fence *fence,
-				    const struct ttm_operation_ctx *ctx)
-{
-	unsigned int i;
-	int ret;
-
-	if (!fence)
-		return 0;
-
-	if (dma_fence_is_signaled(fence)) {
-		ret = fence->error;
-		if (ret)
-			i915_deps_fini(deps);
-		return ret;
-	}
-
-	for (i = 0; i < deps->num_deps; ++i) {
-		struct dma_fence *entry = deps->fences[i];
-
-		if (!entry->context || entry->context != fence->context)
-			continue;
-
-		if (dma_fence_is_later(fence, entry)) {
-			dma_fence_put(entry);
-			deps->fences[i] = dma_fence_get(fence);
-		}
-
-		return 0;
-	}
-
-	return i915_deps_grow(deps, fence, ctx);
-}
-
-static int i915_deps_add_resv(struct i915_deps *deps, struct dma_resv *resv,
-			      const struct ttm_operation_ctx *ctx)
-{
-	struct dma_resv_iter iter;
-	struct dma_fence *fence;
-	int ret;
-
-	dma_resv_assert_held(resv);
-	dma_resv_for_each_fence(&iter, resv, true, fence) {
-		ret = i915_deps_add_dependency(deps, fence, ctx);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-
 static enum i915_cache_level
 i915_ttm_cache_level(struct drm_i915_private *i915, struct ttm_resource *res,
 		     struct ttm_tt *ttm)

drivers/gpu/drm/i915/gem/i915_gem_ttm_move.h

@@ -18,23 +18,6 @@ struct ttm_tt;
 struct drm_i915_gem_object;
 struct i915_refct_sgt;
 
-/**
- * struct i915_deps - Collect dependencies into a single dma-fence
- * @single: Storage for pointer if the collection is a single fence.
- * @fences: Allocated array of fence pointers if more than a single fence;
- * otherwise points to the address of @single.
- * @num_deps: Current number of dependency fences.
- * @fences_size: Size of the @fences array in number of pointers.
- * @gfp: Allocation mode.
- */
-struct i915_deps {
-	struct dma_fence *single;
-	struct dma_fence **fences;
-	unsigned int num_deps;
-	unsigned int fences_size;
-	gfp_t gfp;
-};
-
 int i915_ttm_move_notify(struct ttm_buffer_object *bo);
 
 I915_SELFTEST_DECLARE(void i915_ttm_migrate_set_failure_modes(bool gpu_migration,