drm/armada: use a private mutex to protect priv->linear

Reusing the Big DRM Lock just leaks, and the few things left that
dev->struct_mutex protected are very well contained - it's just the
linear drm_mm manager.

With this armada is completely struct_mutex free!

v2: Convert things properly and also take the lock in
armada_gem_free_object, and remove the stale comment (Russell).

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

4 files changed, 14 insertions, 8 deletions

diff --git a/drivers/gpu/drm/armada/armada_debugfs.c b/drivers/gpu/drm/armada/armada_debugfs.c
index 471e45627f1e..d4f7ab0a30d4 100644
--- a/drivers/gpu/drm/armada/armada_debugfs.c
+++ b/drivers/gpu/drm/armada/armada_debugfs.c
@@ -21,9 +21,9 @@ static int armada_debugfs_gem_linear_show(struct seq_file *m, void *data)
         struct armada_private *priv = dev->dev_private;
         int ret;
 
-        mutex_lock(&dev->struct_mutex);
+        mutex_lock(&priv->linear_lock);
         ret = drm_mm_dump_table(m, &priv->linear);
-        mutex_unlock(&dev->struct_mutex);
+        mutex_unlock(&priv->linear_lock);
 
         return ret;
 }
diff --git a/drivers/gpu/drm/armada/armada_drm.h b/drivers/gpu/drm/armada/armada_drm.h
index 4df6f2af2b21..3b2bb6128d40 100644
--- a/drivers/gpu/drm/armada/armada_drm.h
+++ b/drivers/gpu/drm/armada/armada_drm.h
@@ -57,7 +57,8 @@ struct armada_private {
         DECLARE_KFIFO(fb_unref, struct drm_framebuffer *, 8);
         struct drm_fb_helper    *fbdev;
         struct armada_crtc      *dcrtc[2];
-        struct drm_mm           linear;
+        struct drm_mm           linear; /* protected by linear_lock */
+        struct mutex            linear_lock;
         struct drm_property     *csc_yuv_prop;
         struct drm_property     *csc_rgb_prop;
         struct drm_property     *colorkey_prop;
diff --git a/drivers/gpu/drm/armada/armada_drv.c b/drivers/gpu/drm/armada/armada_drv.c
index 3f1396e673dd..f7f47cb71db4 100644
--- a/drivers/gpu/drm/armada/armada_drv.c
+++ b/drivers/gpu/drm/armada/armada_drv.c
@@ -101,6 +101,7 @@ static int armada_drm_load(struct drm_device *dev, unsigned long flags)
         dev->mode_config.preferred_depth = 24;
         dev->mode_config.funcs = &armada_drm_mode_config_funcs;
         drm_mm_init(&priv->linear, mem->start, resource_size(mem));
+        mutex_init(&priv->linear_lock);
 
         ret = component_bind_all(dev->dev, dev);
         if (ret)
diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
index e3a86b96af2a..6e731db31aa4 100644
--- a/drivers/gpu/drm/armada/armada_gem.c
+++ b/drivers/gpu/drm/armada/armada_gem.c
@@ -46,22 +46,26 @@ static size_t roundup_gem_size(size_t size)
         return roundup(size, PAGE_SIZE);
 }
 
-/* dev->struct_mutex is held here */
 void armada_gem_free_object(struct drm_gem_object *obj)
 {
         struct armada_gem_object *dobj = drm_to_armada_gem(obj);
+        struct armada_private *priv = obj->dev->dev_private;
 
         DRM_DEBUG_DRIVER("release obj %p\n", dobj);
 
         drm_gem_free_mmap_offset(&dobj->obj);
 
+        might_lock(&priv->linear_lock);
+
         if (dobj->page) {
                 /* page backed memory */
                 unsigned int order = get_order(dobj->obj.size);
                 __free_pages(dobj->page, order);
         } else if (dobj->linear) {
                 /* linear backed memory */
+                mutex_lock(&priv->linear_lock);
                 drm_mm_remove_node(dobj->linear);
+                mutex_unlock(&priv->linear_lock);
                 kfree(dobj->linear);
                 if (dobj->addr)
                         iounmap(dobj->addr);
@@ -144,10 +148,10 @@ armada_gem_linear_back(struct drm_device *dev, struct armada_gem_object *obj)
                 if (!node)
                         return -ENOSPC;
 
-                mutex_lock(&dev->struct_mutex);
+                mutex_lock(&priv->linear_lock);
                 ret = drm_mm_insert_node(&priv->linear, node, size, align,
                                          DRM_MM_SEARCH_DEFAULT);
-                mutex_unlock(&dev->struct_mutex);
+                mutex_unlock(&priv->linear_lock);
                 if (ret) {
                         kfree(node);
                         return ret;
@@ -158,9 +162,9 @@ armada_gem_linear_back(struct drm_device *dev, struct armada_gem_object *obj)
                 /* Ensure that the memory we're returning is cleared. */
                 ptr = ioremap_wc(obj->linear->start, size);
                 if (!ptr) {
-                        mutex_lock(&dev->struct_mutex);
+                        mutex_lock(&priv->linear_lock);
                         drm_mm_remove_node(obj->linear);
-                        mutex_unlock(&dev->struct_mutex);
+                        mutex_unlock(&priv->linear_lock);
                         kfree(obj->linear);
                         obj->linear = NULL;
                         return -ENOMEM;