drm/nouveau: Add a separate class for the kernel channel mutex.

nouveau_bo_move_m2mf() needs to lock the kernel channel, and it may be
called from the pushbuf IOCTL with an user channel already locked. Use
a separate subclass for the kernel channel mutex because this is
legitimate mutex nesting.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 6 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index cdc8f544d47f..099f806f39ed 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -678,7 +678,7 @@ nouveau_bo_move_m2mf(struct ttm_buffer_object *bo, int evict, bool intr,
         chan = nvbo->channel;
         if (!chan || nvbo->no_vm) {
                 chan = dev_priv->channel;
-                mutex_lock(&chan->mutex);
+                mutex_lock_nested(&chan->mutex, NOUVEAU_KCHANNEL_MUTEX);
         }
 
         if (dev_priv->card_type < NV_50)
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 5814db82f778..ce0475ead381 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -173,6 +173,11 @@ struct nouveau_page_flip_state {
         uint64_t offset;
 };
 
+enum nouveau_channel_mutex_class {
+        NOUVEAU_UCHANNEL_MUTEX,
+        NOUVEAU_KCHANNEL_MUTEX
+};
+
 struct nouveau_channel {
         struct drm_device *dev;
         int id;