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.hellst...@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.a...@intel.com>
---
 drivers/gpu/drm/i915/Makefile                |   1 +
 drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 171 +------------
 drivers/gpu/drm/i915/gem/i915_gem_ttm_move.h |  17 --
 drivers/gpu/drm/i915/i915_deps.c             | 237 +++++++++++++++++++
 drivers/gpu/drm/i915/i915_deps.h             |  45 ++++
 drivers/gpu/drm/i915/i915_request.c          |   2 +-
 6 files changed, 285 insertions(+), 188 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/i915_deps.c
 create mode 100644 drivers/gpu/drm/i915/i915_deps.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 6ddd2d2bbaaf..1b62b9f65196 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/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 \
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c 
b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
index 5dbaccf3f201..ee9612a3ee5e 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
+++ b/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)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.h 
b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.h
index 138b7647a558..d2e7f149e05c 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.h
+++ b/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,
diff --git a/drivers/gpu/drm/i915/i915_deps.c b/drivers/gpu/drm/i915/i915_deps.c
new file mode 100644
index 000000000000..999210b37325
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_deps.c
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/slab.h>
+
+#include <drm/ttm/ttm_bo_api.h>
+
+#include "i915_deps.h"
+
+/**
+ * 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.
+ */
+
+/* Min number of fence pointers in the array when an allocation occurs. */
+#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;
+}
+
+/**
+ * i915_deps_init - Initialize an i915_deps structure
+ * @deps: Pointer to the i915_deps structure to initialize.
+ * @gfp: The allocation mode for subsequenst allocations.
+ */
+void i915_deps_init(struct i915_deps *deps, gfp_t gfp)
+{
+       deps->fences = NULL;
+       deps->gfp = gfp;
+       i915_deps_reset_fences(deps);
+}
+
+/**
+ * i915_deps_fini - Finalize an i915_deps structure
+ * @deps: Pointer to the i915_deps structure to finalize.
+ *
+ * This function drops all fence references taken, conditionally frees and
+ * then resets the fences array.
+ */
+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;
+}
+
+/**
+ * i915_deps_sync - Wait for all the fences in the dependency collection
+ * @deps: Pointer to the i915_deps structure the fences of which to wait for.
+ * @ctx: Pointer to a struct ttm_operation_ctx indicating how the waits
+ * should be performed.
+ *
+ * This function waits for fences in the dependency collection. If it
+ * encounters an error during the wait or a fence error, the wait for
+ * further fences is aborted and the error returned.
+ *
+ * Return: Zero if successful, Negative error code on error.
+ */
+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;
+}
+
+/**
+ * i915_deps_add_dependency - Add a fence to the dependency collection
+ * @deps: Pointer to the i915_deps structure a fence is to be added to.
+ * @fence: The fence to add.
+ * @ctx: Pointer to a struct ttm_operation_ctx indicating how waits are to
+ * be performed if waiting.
+ *
+ * Adds a fence to the dependency collection, and takes a reference on it.
+ * If the fence context is not zero and there was a later fence from the
+ * same fence context already added, then the fence is not added to the
+ * dependency collection. If the fence context is not zero and there was
+ * an earlier fence already added, then the fence will replace the older
+ * fence from the same context and the reference on the earlier fence will
+ * be dropped.
+ * If there is a failure to allocate memory to accommodate the new fence to
+ * be added, the new fence will instead be waited for and an error may
+ * be returned; depending on the value of @ctx, or if there was a fence
+ * error. If an error was returned, the dependency collection will be
+ * finalized and all fence reference dropped.
+ *
+ * Return: 0 if success. Negative error code on error.
+ */
+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);
+}
+
+/**
+ * i915_deps_add_resv - Add the fences of a reservation object to a dependency
+ * collection.
+ * @deps: Pointer to the i915_deps structure a fence is to be added to.
+ * @resv: The reservation object, then fences of which to add.
+ * @ctx: Pointer to a struct ttm_operation_ctx indicating how waits are to
+ * be performed if waiting.
+ *
+ * Calls i915_deps_add_depencency() on the indicated fences of @resv.
+ *
+ * Return: Zero on success. Negative error code on error.
+ */
+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;
+
+       dma_resv_assert_held(resv);
+       dma_resv_for_each_fence(&iter, resv, true, fence) {
+               int ret = i915_deps_add_dependency(deps, fence, ctx);
+
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
diff --git a/drivers/gpu/drm/i915/i915_deps.h b/drivers/gpu/drm/i915/i915_deps.h
new file mode 100644
index 000000000000..d76c0106c910
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_deps.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#ifndef _I915_DEPS_H_
+#define _I915_DEPS_H_
+
+#include <linux/types.h>
+
+struct ttm_operation_ctx;
+struct dma_fence;
+struct dma_resv;
+
+/**
+ * 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;
+};
+
+void i915_deps_init(struct i915_deps *deps, gfp_t gfp);
+
+void i915_deps_fini(struct i915_deps *deps);
+
+int i915_deps_add_dependency(struct i915_deps *deps,
+                            struct dma_fence *fence,
+                            const struct ttm_operation_ctx *ctx);
+
+int i915_deps_add_resv(struct i915_deps *deps, struct dma_resv *resv,
+                      const struct ttm_operation_ctx *ctx);
+
+int i915_deps_sync(const struct i915_deps *deps,
+                  const struct ttm_operation_ctx *ctx);
+#endif
diff --git a/drivers/gpu/drm/i915/i915_request.c 
b/drivers/gpu/drm/i915/i915_request.c
index 7d804df27546..76cf5ac91e94 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -32,7 +32,6 @@
 #include <linux/sched/mm.h>
 
 #include "gem/i915_gem_context.h"
-#include "gem/i915_gem_ttm_move.h"
 #include "gt/intel_breadcrumbs.h"
 #include "gt/intel_context.h"
 #include "gt/intel_engine.h"
@@ -43,6 +42,7 @@
 #include "gt/intel_rps.h"
 
 #include "i915_active.h"
+#include "i915_deps.h"
 #include "i915_drv.h"
 #include "i915_trace.h"
 #include "intel_pm.h"
-- 
2.31.1

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