drm/ttm, drm_xe, Implement ttm_lru_walk_for_evict() using the guarded LRU iteration

To avoid duplicating the tricky bo locking implementation,
Implement ttm_lru_walk_for_evict() using the guarded bo LRU iteration.

To facilitate this, support ticketlocking from the guarded bo LRU
iteration.

v2:
- Clean up some static function interfaces (Christian König)
- Fix Handling -EALREADY from ticketlocking in the loop by
  skipping to the next item. (Intel CI)

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250623155313.4901-4-thomas.hellstrom@linux.intel.com

1 files changed, 7 insertions, 2 deletions

diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
index ab9a6b343a53..894ff7ccd68e 100644
--- a/include/drm/ttm/ttm_bo.h
+++ b/include/drm/ttm/ttm_bo.h
@@ -529,10 +529,15 @@ class_ttm_bo_lru_cursor_lock_ptr(class_ttm_bo_lru_cursor_t *_T)
  * up at looping termination, even if terminated prematurely by, for
  * example a return or break statement. Exiting the loop will also unlock
  * (if needed) and unreference @_bo.
+ *
+ * Return: If locking of a bo returns an error, then iteration is terminated
+ * and @_bo is set to a corresponding error pointer. It's illegal to
+ * dereference @_bo after loop exit.
  */
 #define ttm_bo_lru_for_each_reserved_guarded(_cursor, _man, _arg, _bo)	\
 	scoped_guard(ttm_bo_lru_cursor, _cursor, _man, _arg)		\
-		for ((_bo) = ttm_bo_lru_cursor_first(_cursor); (_bo);	\
-		     (_bo) = ttm_bo_lru_cursor_next(_cursor))
+		for ((_bo) = ttm_bo_lru_cursor_first(_cursor);		\
+		       !IS_ERR_OR_NULL(_bo);				\
+		       (_bo) = ttm_bo_lru_cursor_next(_cursor))
 
 #endif