From: Ben Skeggs <bskeggs@redhat.com>
Date: Wed, 1 Nov 2017 03:56:19 +1000
Subject: drm/nouveau: hang drm client of a master
Git-commit: cb7e88e70f52878f4be0fbcc04350cff72f67278
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

TTM memory allocations will be hanging off the DRM's client, but the
locking needed to do so gets really tricky with all the other use of
the DRM's object tree.

To solve this, we make the normal DRM client a child of a new master,
where the memory allocations will be done from instead.

This also solves a potential race with client creation.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/nouveau/nouveau_drm.c |   20 ++++++++++++++++----
 drivers/gpu/drm/nouveau/nouveau_drv.h |    3 +++
 2 files changed, 19 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -117,7 +117,9 @@ nouveau_cli_fini(struct nouveau_cli *cli
 	nvkm_vm_ref(NULL, &nvxx_client(&cli->base)->vm, NULL);
 	usif_client_fini(cli);
 	nvif_device_fini(&cli->device);
+	mutex_lock(&cli->drm->master.lock);
 	nvif_client_fini(&cli->base);
+	mutex_unlock(&cli->drm->master.lock);
 }
 
 static int
@@ -132,12 +134,16 @@ nouveau_cli_init(struct nouveau_drm *drm
 	mutex_init(&cli->mutex);
 	usif_client_init(cli);
 
-	if (cli == &drm->client) {
+	mutex_init(&cli->lock);
+
+	if (cli == &drm->master) {
 		ret = nvif_driver_init(NULL, nouveau_config, nouveau_debug,
 				       cli->name, device, &cli->base);
 	} else {
-		ret = nvif_client_init(&drm->client.base, cli->name, device,
+		mutex_lock(&drm->master.lock);
+		ret = nvif_client_init(&drm->master.base, cli->name, device,
 				       &cli->base);
+		mutex_unlock(&drm->master.lock);
 	}
 	if (ret) {
 		NV_ERROR(drm, "Client allocation failed: %d\n", ret);
@@ -433,6 +439,10 @@ nouveau_drm_load(struct drm_device *dev,
 	dev->dev_private = drm;
 	drm->dev = dev;
 
+	ret = nouveau_cli_init(drm, "DRM-master", &drm->master);
+	if (ret)
+		return ret;
+
 	ret = nouveau_cli_init(drm, "DRM", &drm->client);
 	if (ret)
 		return ret;
@@ -518,6 +528,7 @@ fail_ttm:
 	nouveau_vga_fini(drm);
 fail_device:
 	nouveau_cli_fini(&drm->client);
+	nouveau_cli_fini(&drm->master);
 	kfree(drm);
 	return ret;
 }
@@ -550,6 +561,7 @@ nouveau_drm_unload(struct drm_device *de
 	if (drm->hdmi_device)
 		pci_dev_put(drm->hdmi_device);
 	nouveau_cli_fini(&drm->client);
+	nouveau_cli_fini(&drm->master);
 	kfree(drm);
 }
 
@@ -618,7 +630,7 @@ nouveau_do_suspend(struct drm_device *de
 	}
 
 	NV_DEBUG(drm, "suspending object tree...\n");
-	ret = nvif_client_suspend(&drm->client.base);
+	ret = nvif_client_suspend(&drm->master.base);
 	if (ret)
 		goto fail_client;
 
@@ -642,7 +654,7 @@ nouveau_do_resume(struct drm_device *dev
 	struct nouveau_drm *drm = nouveau_drm(dev);
 
 	NV_DEBUG(drm, "resuming object tree...\n");
-	nvif_client_resume(&drm->client.base);
+	nvif_client_resume(&drm->master.base);
 
 	NV_DEBUG(drm, "resuming fence...\n");
 	if (drm->fence && nouveau_fence(drm)->resume)
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -97,6 +97,8 @@ struct nouveau_cli {
 	struct list_head objects;
 	struct list_head notifys;
 	char name[32];
+
+	struct mutex lock;
 };
 
 static inline struct nouveau_cli *
@@ -109,6 +111,7 @@ nouveau_cli(struct drm_file *fpriv)
 #include <nvif/device.h>
 
 struct nouveau_drm {
+	struct nouveau_cli master;
 	struct nouveau_cli client;
 	struct drm_device *dev;