drm/omap: gem: Fix mm_list locking

- None of the list walkings where protected.

- Switch to a mutex since the list walking at device resume time can
  sleep when pinning buffers through the tiler.

Only thing we need to be careful with here is that while we walk the
list we can't unreference any gem objects, since the final unref would
result in a recursive deadlock. But the only functions that walk the
list is the device resume and debugfs dumping, so all safe.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

diff --git a/drivers/gpu/drm/omapdrm/omap_debugfs.c b/drivers/gpu/drm/omapdrm/omap_debugfs.c
index 95ade441caa871d83c2ad1f7c18abd1725e4c0ce..91cf043f2b6ba8e17de4956c13701c503df885da 100644 (file)
--- a/drivers/gpu/drm/omapdrm/omap_debugfs.c
+++ b/drivers/gpu/drm/omapdrm/omap_debugfs.c
@@ -32,7 +32,9 @@ static int gem_show(struct seq_file *m, void *arg)
        struct omap_drm_private *priv = dev->dev_private;
 
        seq_printf(m, "All Objects:\n");
+       mutex_lock(&priv->list_lock);
        omap_gem_describe_objects(&priv->obj_list, m);
+       mutex_unlock(&priv->list_lock);
 
        return 0;
 }

diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index ef3b0e3571ec860ee64c3f75d15c08c00b83c011..5fcf9eaf3eafeb5fe01c5719e7f9ccf931511309 100644 (file)
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -540,7 +540,7 @@ static int omapdrm_init(struct omap_drm_private *priv, struct device *dev)
        priv->omaprev = soc ? (unsigned int)soc->data : 0;
        priv->wq = alloc_ordered_workqueue("omapdrm", 0);
 
-       spin_lock_init(&priv->list_lock);
+       mutex_init(&priv->list_lock);
        INIT_LIST_HEAD(&priv->obj_list);
 
        /* Allocate and initialize the DRM device. */

diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index 6eaee4df45594c8d23ba3df0af07244e07c92d6c..f27c8e216adf894f8180f40b0c885b2c683ccd86 100644 (file)
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -71,7 +71,7 @@ struct omap_drm_private {
        struct workqueue_struct *wq;
 
        /* lock for obj_list below */
-       spinlock_t list_lock;
+       struct mutex list_lock;
 
        /* list of GEM objects: */
        struct list_head obj_list;

diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index cebbdf081e5dd46209eabef0dd6aea939f675695..4ba5d035c5909eed0f05b978324186e7ba1b46c0 100644 (file)
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -1000,6 +1000,7 @@ int omap_gem_resume(struct drm_device *dev)
        struct omap_gem_object *omap_obj;
        int ret = 0;
 
+       mutex_lock(&priv->list_lock);
        list_for_each_entry(omap_obj, &priv->obj_list, mm_list) {
                if (omap_obj->block) {
                        struct drm_gem_object *obj = &omap_obj->base;
@@ -1011,12 +1012,14 @@ int omap_gem_resume(struct drm_device *dev)
                                        omap_obj->roll, true);
                        if (ret) {
                                dev_err(dev->dev, "could not repin: %d\n", ret);
-                               return ret;
+                               goto done;
                        }
                }
        }
 
-       return 0;
+done:
+       mutex_unlock(&priv->list_lock);
+       return ret;
 }
 #endif
 
@@ -1086,9 +1089,9 @@ void omap_gem_free_object(struct drm_gem_object *obj)
 
        omap_gem_evict(obj);
 
-       spin_lock(&priv->list_lock);
+       mutex_lock(&priv->list_lock);
        list_del(&omap_obj->mm_list);
-       spin_unlock(&priv->list_lock);
+       mutex_unlock(&priv->list_lock);
 
        /*
         * We own the sole reference to the object at this point, but to keep
@@ -1218,9 +1221,9 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
                        goto err_release;
        }
 
-       spin_lock(&priv->list_lock);
+       mutex_lock(&priv->list_lock);
        list_add(&omap_obj->mm_list, &priv->obj_list);
-       spin_unlock(&priv->list_lock);
+       mutex_unlock(&priv->list_lock);
 
        return obj;