Re: [PATCH v3 02/21] drm/ttm: Slightly clean up LRU list iteration

[Christian König]

Am 21.05.24 um 09:16 schrieb Thomas Hellström:

To make the transition to using lru hitches easier,
simplify the ttm_resource_manager_next() interface to only take
the cursor and reuse ttm_resource_manager_next() functionality
from ttm_resource_manager_first().

Cc: Christian König <christian.koe...@amd.com>
Cc: Somalapuram Amaranath <amaranath.somalapu...@amd.com>
Cc: Matthew Brost <matthew.br...@intel.com>
Cc: <dri-devel@lists.freedesktop.org>
Signed-off-by: Thomas Hellström <thomas.hellst...@linux.intel.com>

Reviewed-by: Christian König <christian.koe...@amd.com>

---
  drivers/gpu/drm/ttm/ttm_resource.c | 48 +++++++++++++-----------------
  include/drm/ttm/ttm_resource.h     | 10 ++++---
  2 files changed, 27 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_resource.c 
b/drivers/gpu/drm/ttm/ttm_resource.c
index db9a7a3717c4..8bfbddddc0e8 100644
--- a/drivers/gpu/drm/ttm/ttm_resource.c
+++ b/drivers/gpu/drm/ttm/ttm_resource.c
@@ -496,50 +496,44 @@ struct ttm_resource *
  ttm_resource_manager_first(struct ttm_resource_manager *man,
                           struct ttm_resource_cursor *cursor)
  {
-       struct ttm_lru_item *lru;
-
        lockdep_assert_held(&man->bdev->lru_lock);

- for (cursor->priority = 0; cursor->priority < TTM_MAX_BO_PRIORITY;

-            ++cursor->priority)
-               list_for_each_entry(lru, &man->lru[cursor->priority], link) {
-                       if (ttm_lru_item_is_res(lru))
-                               return ttm_lru_item_to_res(lru);
-               }
-
-       return NULL;
+       cursor->priority = 0;
+       cursor->man = man;
+       cursor->cur = &man->lru[cursor->priority];
+       return ttm_resource_manager_next(cursor);
  }

/**

   * ttm_resource_manager_next
   *
- * @man: resource manager to iterate over
   * @cursor: cursor to record the position
- * @res: the current resource pointer
   *
- * Returns the next resource from the resource manager.
+ * Return: the next resource from the resource manager.
   */
  struct ttm_resource *
-ttm_resource_manager_next(struct ttm_resource_manager *man,
-                         struct ttm_resource_cursor *cursor,
-                         struct ttm_resource *res)
+ttm_resource_manager_next(struct ttm_resource_cursor *cursor)
  {
-       struct ttm_lru_item *lru = &res->lru;
+       struct ttm_resource_manager *man = cursor->man;
+       struct ttm_lru_item *lru;

lockdep_assert_held(&man->bdev->lru_lock); - list_for_each_entry_continue(lru, &man->lru[cursor->priority], link) {

-               if (ttm_lru_item_is_res(lru))
-                       return ttm_lru_item_to_res(lru);
-       }
-
-       for (++cursor->priority; cursor->priority < TTM_MAX_BO_PRIORITY;
-            ++cursor->priority)
-               list_for_each_entry(lru, &man->lru[cursor->priority], link) {
-                       if (ttm_lru_item_is_res(lru))
-                               ttm_lru_item_to_res(lru);
+       for (;;) {
+               lru = list_entry(cursor->cur, typeof(*lru), link);
+               list_for_each_entry_continue(lru, &man->lru[cursor->priority], 
link) {
+                       if (ttm_lru_item_is_res(lru)) {
+                               cursor->cur = &lru->link;
+                               return ttm_lru_item_to_res(lru);
+                       }
                }

+ if (++cursor->priority >= TTM_MAX_BO_PRIORITY)

+                       break;
+
+               cursor->cur = &man->lru[cursor->priority];
+       }
+
        return NULL;
  }

diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h

index 1511d91e290d..7d81fd5b5b83 100644
--- a/include/drm/ttm/ttm_resource.h
+++ b/include/drm/ttm/ttm_resource.h
@@ -272,11 +272,15 @@ ttm_lru_item_to_res(struct ttm_lru_item *item)
  /**
   * struct ttm_resource_cursor
   *
+ * @man: The resource manager currently being iterated over.
+ * @cur: The list head the cursor currently points to.
   * @priority: the current priority
   *
   * Cursor to iterate over the resources in a manager.
   */
  struct ttm_resource_cursor {
+       struct ttm_resource_manager *man;
+       struct list_head *cur;
        unsigned int priority;
  };

@@ -438,9 +442,7 @@ struct ttm_resource *

  ttm_resource_manager_first(struct ttm_resource_manager *man,
                           struct ttm_resource_cursor *cursor);
  struct ttm_resource *
-ttm_resource_manager_next(struct ttm_resource_manager *man,
-                         struct ttm_resource_cursor *cursor,
-                         struct ttm_resource *res);
+ttm_resource_manager_next(struct ttm_resource_cursor *cursor);

struct ttm_resource *

  ttm_lru_first_res_or_null(struct list_head *head);
@@ -455,7 +457,7 @@ ttm_lru_first_res_or_null(struct list_head *head);
   */
  #define ttm_resource_manager_for_each_res(man, cursor, res)           \
        for (res = ttm_resource_manager_first(man, cursor); res;        \
-            res = ttm_resource_manager_next(man, cursor, res))
+            res = ttm_resource_manager_next(cursor))

struct ttm_kmap_iter *

  ttm_kmap_iter_iomap_init(struct ttm_kmap_iter_iomap *iter_io,