Allow specifying a drm_exec object in TTMs operation context which is
used to lock objects during eviction.

This allows to handle deadlocks much more gracefully and with that
avoid returning -ENOMEM on heavily contended domains.

v2: rebased on top of Thomas work
v3: rebased again
v4: adjust to dma_resv changes

Signed-off-by: Christian König <[email protected]>
---
 drivers/gpu/drm/ttm/ttm_bo_util.c | 12 ++++++++----
 include/drm/ttm/ttm_bo.h          |  5 +++++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c 
b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 1bdd69643c313..570640ae79d84 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -38,6 +38,7 @@
 #include <drm/ttm/ttm_tt.h>
 
 #include <drm/drm_cache.h>
+#include <drm/drm_exec.h>
 
 struct ttm_transfer_obj {
        struct ttm_buffer_object base;
@@ -839,7 +840,9 @@ static int ttm_lru_walk_ticketlock(struct ttm_bo_lru_cursor 
*curs,
        struct ttm_lru_walk_arg *arg = curs->arg;
        int ret;
 
-       if (arg->ctx->interruptible)
+       if (arg->ctx->exec)
+               ret = drm_exec_lock_resv(arg->ctx->exec, resv);
+       else if (arg->ctx->interruptible)
                ret = dma_resv_lock_interruptible(resv, arg->ticket);
        else
                ret = dma_resv_lock(resv, arg->ticket);
@@ -853,7 +856,8 @@ static int ttm_lru_walk_ticketlock(struct ttm_bo_lru_cursor 
*curs,
                 * trylocking for this walk.
                 */
                arg->ticket = NULL;
-       } else if (ret == -EDEADLK) {
+
+       } else if (!arg->ctx->exec && ret == -EDEADLK) {
                /* Caller needs to exit the ww transaction. */
                ret = -ENOSPC;
        }
@@ -993,8 +997,8 @@ __ttm_bo_lru_cursor_iter(struct ttm_bo_lru_cursor *curs, 
bool first)
                if (!ttm_lru_walk_trylock(curs, res->bo->base.resv)) {
                        struct dma_resv *resv;
 
-                       if (!arg->ticket || arg->ctx->no_wait_gpu ||
-                           arg->trylock_only) {
+                       if ((!arg->ticket || arg->ctx->no_wait_gpu ||
+                            arg->trylock_only) && !arg->ctx->exec) {
                                spin_unlock(lru_lock);
                                continue;
                        }
diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
index e1221e3be7bda..0ffa84a5caa65 100644
--- a/include/drm/ttm/ttm_bo.h
+++ b/include/drm/ttm/ttm_bo.h
@@ -186,6 +186,11 @@ struct ttm_operation_ctx {
         * @bytes_moved: Statistics on how many bytes have been moved.
         */
        uint64_t bytes_moved;
+       /*
+        * @exec: optional drm_exec object to use for locking and contention
+        * handling
+        */
+       struct drm_exec *exec;
 };
 
 struct ttm_lru_walk;
-- 
2.43.0

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