[PATCH 10/12] drm/exec: add drm_exec_lock_resv function
From: Christian König
Date: Fri Jul 10 2026 - 15:14:02 EST
Restructure the drm_exec object to work with dma_resv references instead
of GEM object references.
Add the new function dma_exec_lock_resv() to lock individual dma_resv
objects and so allow higher level implementations to handle contention
purely on dma_resv objects.
WIP! Don't commit like that!
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/drm_exec.c | 75 ++++++++++++++++++++++----------------
drivers/gpu/drm/drm_gem.c | 2 +
include/drm/drm_exec.h | 9 +++--
3 files changed, 50 insertions(+), 36 deletions(-)
diff --git a/drivers/gpu/drm/drm_exec.c b/drivers/gpu/drm/drm_exec.c
index fa923852fae45..382bf7bcd5ff3 100644
--- a/drivers/gpu/drm/drm_exec.c
+++ b/drivers/gpu/drm/drm_exec.c
@@ -58,8 +58,11 @@ static void drm_exec_unlock_all(struct drm_exec *exec)
drm_gem_object_put(obj);
}
- drm_gem_object_put(exec->prelocked);
- exec->prelocked = NULL;
+ if (exec->prelocked) {
+ dma_resv_unlock(exec->prelocked);
+ dma_resv_put(exec->prelocked);
+ exec->prelocked = NULL;
+ }
}
/**
@@ -101,7 +104,7 @@ void drm_exec_fini(struct drm_exec *exec)
drm_exec_unlock_all(exec);
kvfree(exec->objects);
if (exec->contended != DRM_EXEC_DUMMY) {
- drm_gem_object_put(exec->contended);
+ dma_resv_put(exec->contended);
ww_acquire_fini(&exec->ticket);
}
}
@@ -158,50 +161,41 @@ static int drm_exec_obj_locked(struct drm_exec *exec,
/* Make sure the contended object is locked first */
static int drm_exec_lock_contended(struct drm_exec *exec)
{
- struct drm_gem_object *obj = exec->contended;
+ struct dma_resv *resv = exec->contended;
int ret;
- if (likely(!obj))
+ if (likely(!resv))
return 0;
/* Always cleanup the contention so that error handling can kick in */
exec->contended = NULL;
if (exec->flags & DRM_EXEC_INTERRUPTIBLE_WAIT) {
- ret = dma_resv_lock_slow_interruptible(obj->resv,
- &exec->ticket);
+ ret = dma_resv_lock_slow_interruptible(resv, &exec->ticket);
if (unlikely(ret))
goto error_dropref;
} else {
- dma_resv_lock_slow(obj->resv, &exec->ticket);
+ dma_resv_lock_slow(resv, &exec->ticket);
}
- ret = drm_exec_obj_locked(exec, obj);
- if (unlikely(ret))
- goto error_unlock;
-
- exec->prelocked = obj;
+ exec->prelocked = resv;
return 0;
-error_unlock:
- dma_resv_unlock(obj->resv);
-
error_dropref:
- drm_gem_object_put(obj);
+ dma_resv_put(resv);
return ret;
}
/**
- * drm_exec_lock_obj - lock a GEM object for use
+ * drm_exec_lock_resv - lock a dma_resv object
* @exec: the drm_exec object with the state
- * @obj: the GEM object to lock
+ * @resv: the dma_resv object to lock
*
- * Lock a GEM object for use and grab a reference to it.
+ * Lock a dma_resv object for use or grab a reference to it on contention.
*
* Returns: -EDEADLK if a contention is detected, -EALREADY when object is
- * already locked (can be suppressed by setting the DRM_EXEC_IGNORE_DUPLICATES
- * flag), -ENOMEM when memory allocation failed and zero for success.
+ * already locked, -ENOMEM when memory allocation failed and zero for success.
*/
-int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj)
+int drm_exec_lock_resv(struct drm_exec *exec, struct dma_resv *resv)
{
int ret;
@@ -209,22 +203,39 @@ int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj)
if (unlikely(ret))
return ret;
- if (exec->prelocked == obj) {
- drm_gem_object_put(exec->prelocked);
+ if (exec->prelocked == resv) {
+ dma_resv_put(exec->prelocked);
exec->prelocked = NULL;
return 0;
}
if (exec->flags & DRM_EXEC_INTERRUPTIBLE_WAIT)
- ret = dma_resv_lock_interruptible(obj->resv, &exec->ticket);
+ ret = dma_resv_lock_interruptible(resv, &exec->ticket);
else
- ret = dma_resv_lock(obj->resv, &exec->ticket);
+ ret = dma_resv_lock(resv, &exec->ticket);
- if (unlikely(ret == -EDEADLK)) {
- drm_gem_object_get(obj);
- exec->contended = obj;
- return -EDEADLK;
- }
+ if (unlikely(ret == -EDEADLK))
+ exec->contended = dma_resv_get(resv);
+ return ret;
+}
+EXPORT_SYMBOL(drm_exec_lock_resv);
+
+/**
+ * drm_exec_lock_obj - lock a GEM object for use
+ * @exec: the drm_exec object with the state
+ * @obj: the GEM object to lock
+ *
+ * Lock a GEM object for use and grab a reference to it.
+ *
+ * Returns: -EDEADLK if a contention is detected, -EALREADY when object is
+ * already locked (can be suppressed by setting the DRM_EXEC_IGNORE_DUPLICATES
+ * flag), -ENOMEM when memory allocation failed and zero for success.
+ */
+int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj)
+{
+ int ret;
+
+ ret = drm_exec_lock_resv(exec, obj->resv);
if (unlikely(ret == -EALREADY) &&
exec->flags & DRM_EXEC_IGNORE_DUPLICATES)
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index bbcbd25f014f0..f5cf9ad596a67 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -229,6 +229,8 @@ void drm_gem_private_object_init(struct drm_device *dev,
obj->size = size;
mutex_init(&obj->gpuva.lock);
dma_resv_init(&obj->_resv);
+
+ /* TODO: This needs to go away for drm_exec to work correctly!!! */
if (!obj->resv)
obj->resv = dma_resv_get(&obj->_resv);
diff --git a/include/drm/drm_exec.h b/include/drm/drm_exec.h
index 8725ba92ff916..9daedb676d7b1 100644
--- a/include/drm/drm_exec.h
+++ b/include/drm/drm_exec.h
@@ -47,14 +47,14 @@ struct drm_exec {
struct drm_gem_object **objects;
/**
- * @contended: contended GEM object we backed off for
+ * @contended: contended dma_resv object we backed off for
*/
- struct drm_gem_object *contended;
+ struct dma_resv *contended;
/**
- * @prelocked: already locked GEM object due to contention
+ * @prelocked: already locked dma_resv object due to contention
*/
- struct drm_gem_object *prelocked;
+ struct dma_resv *prelocked;
};
/**
@@ -175,6 +175,7 @@ static inline struct ww_acquire_ctx *drm_exec_ticket(struct drm_exec *exec)
void drm_exec_init(struct drm_exec *exec, u32 flags, unsigned nr);
void drm_exec_fini(struct drm_exec *exec);
bool drm_exec_cleanup(struct drm_exec *exec);
+int drm_exec_lock_resv(struct drm_exec *exec, struct dma_resv *resv);
int drm_exec_lock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
void drm_exec_unlock_obj(struct drm_exec *exec, struct drm_gem_object *obj);
int drm_exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
--
2.43.0