[PATCH 2/2] drm/nouveau: require cli->mutex in RING_SPACE

[Maarten Lankhorst]

There are some cases where it's fine to not hold the cli->mutex, but in those 
cases we
are the only caller and we should really be able to acquire cli->mutex without 
blocking.

This patch will prevent future occurrences where commands are sent to a channel 
without
proper locking.

Signed-off-by: Maarten Lankhorst<maarten.lankhorst at canonical.com>
---
diff --git a/drivers/gpu/drm/nouveau/nouveau_abi16.c 
b/drivers/gpu/drm/nouveau/nouveau_abi16.c
index 900fae01793e..20959e445d05 100644
--- a/drivers/gpu/drm/nouveau/nouveau_abi16.c
+++ b/drivers/gpu/drm/nouveau/nouveau_abi16.c
@@ -153,10 +153,12 @@ nouveau_abi16_fini(struct nouveau_abi16 *abi16)
        struct nouveau_cli *cli = (void *)abi16->client;
        struct nouveau_abi16_chan *chan, *temp;

+       mutex_lock(&cli->mutex);
        /* cleanup channels */
        list_for_each_entry_safe(chan, temp, &abi16->channels, head) {
                nouveau_abi16_chan_fini(abi16, chan);
        }
+       mutex_unlock(&cli->mutex);

        /* destroy the device object */
        nouveau_object_del(abi16->client, NVDRM_CLIENT, NVDRM_DEVICE);
diff --git a/drivers/gpu/drm/nouveau/nouveau_dma.h 
b/drivers/gpu/drm/nouveau/nouveau_dma.h
index 984004d66a6d..82465bd0b59b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dma.h
+++ b/drivers/gpu/drm/nouveau/nouveau_dma.h
@@ -107,6 +107,7 @@ RING_SPACE(struct nouveau_channel *chan, int size)
  {
        int ret;

+       lockdep_assert_held(&chan->cli->mutex);
        ret = nouveau_dma_wait(chan, 1, size);
        if (ret)
                return ret;
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c 
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index f7a6568cfa6a..a60c404d59e4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -476,7 +476,9 @@ nouveau_drm_load(struct drm_device *dev, unsigned long 
flags)

        nouveau_sysfs_init(dev);
        nouveau_hwmon_init(dev);
+       mutex_lock(&drm->client.mutex);
        nouveau_accel_init(drm);
+       mutex_unlock(&drm->client.mutex);
        nouveau_fbcon_init(dev);

        if (nouveau_runtime_pm != 0) {
@@ -562,17 +564,17 @@ nouveau_do_suspend(struct drm_device *dev)
        ttm_bo_evict_mm(&drm->ttm.bdev, TTM_PL_VRAM);

        NV_INFO(drm, "waiting for kernel channels to go idle...\n");
-       if (drm->cechan) {
+       ret = 0;
+       mutex_lock(&drm->client.mutex);
+       if (drm->cechan)
                ret = nouveau_channel_idle(drm->cechan);
-               if (ret)
-                       return ret;
-       }

-       if (drm->channel) {
+       if (drm->channel && !ret)
                ret = nouveau_channel_idle(drm->channel);
-               if (ret)
-                       return ret;
-       }
+       mutex_unlock(&drm->client.mutex);
+       if (ret)
+               return ret;
+

        NV_INFO(drm, "suspending client object trees...\n");
        if (drm->fence && nouveau_fence(drm)->suspend) {
diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c 
b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index 7903e0ed3c75..aec87e1d3855 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -357,7 +357,7 @@ nouveau_fbcon_create(struct drm_fb_helper *helper,

        mutex_unlock(&dev->struct_mutex);

-       if (chan) {
+       if (chan && !WARN_ON(!mutex_trylock(&drm->client.mutex))) {
                ret = -ENODEV;
                if (device->card_type < NV_50)
                        ret = nv04_fbcon_accel_init(info);
@@ -366,6 +366,7 @@ nouveau_fbcon_create(struct drm_fb_helper *helper,
                        ret = nv50_fbcon_accel_init(info);
                else
                        ret = nvc0_fbcon_accel_init(info);
+               mutex_unlock(&drm->client.mutex);

                if (ret == 0)
                        info->fbops = &nouveau_fbcon_ops;