drm/nouveau/engine: use refcount_t + private mutex

nvkm_subdev.mutex is going away.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/include/nvkm/core/engine.h b/drivers/gpu/drm/nouveau/include/nvkm/core/engine.h
index c6b401a..c9d84bd 100644 (file)
--- a/drivers/gpu/drm/nouveau/include/nvkm/core/engine.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/core/engine.h
@@ -11,7 +11,11 @@ struct nvkm_engine {
        struct nvkm_subdev subdev;
        spinlock_t lock;
 
-       int usecount;
+       struct {
+               refcount_t refcount;
+               struct mutex mutex;
+               bool enabled;
+       } use;
 };
 
 struct nvkm_engine_func {

diff --git a/drivers/gpu/drm/nouveau/nvkm/core/engine.c b/drivers/gpu/drm/nouveau/nvkm/core/engine.c
index 1a47c40..8220a0d 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/core/engine.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/engine.c
@@ -40,10 +40,11 @@ nvkm_engine_unref(struct nvkm_engine **pengine)
 {
        struct nvkm_engine *engine = *pengine;
        if (engine) {
-               mutex_lock(&engine->subdev.mutex);
-               if (--engine->usecount == 0)
+               if (refcount_dec_and_mutex_lock(&engine->use.refcount, &engine->use.mutex)) {
                        nvkm_subdev_fini(&engine->subdev, false);
-               mutex_unlock(&engine->subdev.mutex);
+                       engine->use.enabled = false;
+                       mutex_unlock(&engine->use.mutex);
+               }
                *pengine = NULL;
        }
 }
@@ -51,17 +52,21 @@ nvkm_engine_unref(struct nvkm_engine **pengine)
 struct nvkm_engine *
 nvkm_engine_ref(struct nvkm_engine *engine)
 {
+       int ret;
        if (engine) {
-               mutex_lock(&engine->subdev.mutex);
-               if (++engine->usecount == 1) {
-                       int ret = nvkm_subdev_init(&engine->subdev);
-                       if (ret) {
-                               engine->usecount--;
-                               mutex_unlock(&engine->subdev.mutex);
-                               return ERR_PTR(ret);
+               if (!refcount_inc_not_zero(&engine->use.refcount)) {
+                       mutex_lock(&engine->use.mutex);
+                       if (!refcount_inc_not_zero(&engine->use.refcount)) {
+                               engine->use.enabled = true;
+                               if ((ret = nvkm_subdev_init(&engine->subdev))) {
+                                       engine->use.enabled = false;
+                                       mutex_unlock(&engine->use.mutex);
+                                       return ERR_PTR(ret);
+                               }
+                               refcount_set(&engine->use.refcount, 1);
                        }
+                       mutex_unlock(&engine->use.mutex);
                }
-               mutex_unlock(&engine->subdev.mutex);
        }
        return engine;
 }
@@ -114,7 +119,7 @@ nvkm_engine_init(struct nvkm_subdev *subdev)
        int ret = 0, i;
        s64 time;
 
-       if (!engine->usecount) {
+       if (!engine->use.enabled) {
                nvkm_trace(subdev, "init skipped, engine has no users\n");
                return ret;
        }
@@ -156,6 +161,7 @@ nvkm_engine_dtor(struct nvkm_subdev *subdev)
        struct nvkm_engine *engine = nvkm_engine(subdev);
        if (engine->func->dtor)
                return engine->func->dtor(engine);
+       mutex_destroy(&engine->use.mutex);
        return engine;
 }
 
@@ -176,6 +182,8 @@ nvkm_engine_ctor(const struct nvkm_engine_func *func,
 {
        nvkm_subdev_ctor(&nvkm_engine_func, device, index, &engine->subdev);
        engine->func = func;
+       refcount_set(&engine->use.refcount, 0);
+       mutex_init(&engine->use.mutex);
 
        if (!nvkm_boolopt(device->cfgopt, nvkm_subdev_name[index], enable)) {
                nvkm_debug(&engine->subdev, "disabled\n");