drm/i915: Add a spinlock to protect the active_list

This is a baby-step in the direction of having finer-grained
locking than the struct_mutex. Specifically, this will enable
new debugging code to read the active list for printing out
GPU state when the GPU is wedged, (while the struct_mutex is
held, of course).

Signed-off-by: Carl Worth <cworth@cworth.org>
[anholt: indentation fix]
Signed-off-by: Eric Anholt <eric@anholt.net>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c0f48bb..317b122 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -300,6 +300,7 @@ typedef struct drm_i915_private {
                 *
                 * A reference is held on the buffer while on this list.
                 */
+               spinlock_t active_list_lock;
                struct list_head active_list;
 
                /**

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 9f4eceb..1449b45 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1325,8 +1325,10 @@ i915_gem_object_move_to_active(struct drm_gem_object *obj, uint32_t seqno)
                obj_priv->active = 1;
        }
        /* Move from whatever list we were on to the tail of execution. */
+       spin_lock(&dev_priv->mm.active_list_lock);
        list_move_tail(&obj_priv->list,
                       &dev_priv->mm.active_list);
+       spin_unlock(&dev_priv->mm.active_list_lock);
        obj_priv->last_rendering_seqno = seqno;
 }
 
@@ -1468,6 +1470,7 @@ i915_gem_retire_request(struct drm_device *dev,
        /* Move any buffers on the active list that are no longer referenced
         * by the ringbuffer to the flushing/inactive lists as appropriate.
         */
+       spin_lock(&dev_priv->mm.active_list_lock);
        while (!list_empty(&dev_priv->mm.active_list)) {
                struct drm_gem_object *obj;
                struct drm_i915_gem_object *obj_priv;
@@ -1482,7 +1485,7 @@ i915_gem_retire_request(struct drm_device *dev,
                 * this seqno.
                 */
                if (obj_priv->last_rendering_seqno != request->seqno)
-                       return;
+                       goto out;
 
 #if WATCH_LRU
                DRM_INFO("%s: retire %d moves to inactive list %p\n",
@@ -1494,6 +1497,8 @@ i915_gem_retire_request(struct drm_device *dev,
                else
                        i915_gem_object_move_to_inactive(obj);
        }
+out:
+       spin_unlock(&dev_priv->mm.active_list_lock);
 }
 
 /**
@@ -2215,15 +2220,20 @@ i915_gem_object_bind_to_gtt(struct drm_gem_object *obj, unsigned alignment)
                }
        }
        if (obj_priv->gtt_space == NULL) {
+               bool lists_empty;
+
                /* If the gtt is empty and we're still having trouble
                 * fitting our object in, we're out of memory.
                 */
 #if WATCH_LRU
                DRM_INFO("%s: GTT full, evicting something\n", __func__);
 #endif
-               if (list_empty(&dev_priv->mm.inactive_list) &&
-                   list_empty(&dev_priv->mm.flushing_list) &&
-                   list_empty(&dev_priv->mm.active_list)) {
+               spin_lock(&dev_priv->mm.active_list_lock);
+               lists_empty = (list_empty(&dev_priv->mm.inactive_list) &&
+                              list_empty(&dev_priv->mm.flushing_list) &&
+                              list_empty(&dev_priv->mm.active_list));
+               spin_unlock(&dev_priv->mm.active_list_lock);
+               if (lists_empty) {
                        DRM_ERROR("GTT full, but LRU list empty\n");
                        return -ENOMEM;
                }
@@ -3679,6 +3689,7 @@ i915_gem_idle(struct drm_device *dev)
 
        i915_gem_retire_requests(dev);
 
+       spin_lock(&dev_priv->mm.active_list_lock);
        if (!dev_priv->mm.wedged) {
                /* Active and flushing should now be empty as we've
                 * waited for a sequence higher than any pending execbuffer
@@ -3705,6 +3716,7 @@ i915_gem_idle(struct drm_device *dev)
                obj_priv->obj->write_domain &= ~I915_GEM_GPU_DOMAINS;
                i915_gem_object_move_to_inactive(obj_priv->obj);
        }
+       spin_unlock(&dev_priv->mm.active_list_lock);
 
        while (!list_empty(&dev_priv->mm.flushing_list)) {
                struct drm_i915_gem_object *obj_priv;
@@ -3953,7 +3965,10 @@ i915_gem_entervt_ioctl(struct drm_device *dev, void *data,
        if (ret != 0)
                return ret;
 
+       spin_lock(&dev_priv->mm.active_list_lock);
        BUG_ON(!list_empty(&dev_priv->mm.active_list));
+       spin_unlock(&dev_priv->mm.active_list_lock);
+
        BUG_ON(!list_empty(&dev_priv->mm.flushing_list));
        BUG_ON(!list_empty(&dev_priv->mm.inactive_list));
        BUG_ON(!list_empty(&dev_priv->mm.request_list));
@@ -3997,6 +4012,7 @@ i915_gem_load(struct drm_device *dev)
 {
        drm_i915_private_t *dev_priv = dev->dev_private;
 
+       spin_lock_init(&dev_priv->mm.active_list_lock);
        INIT_LIST_HEAD(&dev_priv->mm.active_list);
        INIT_LIST_HEAD(&dev_priv->mm.flushing_list);
        INIT_LIST_HEAD(&dev_priv->mm.inactive_list);

diff --git a/drivers/gpu/drm/i915/i915_gem_debug.c b/drivers/gpu/drm/i915/i915_gem_debug.c
index 131c088..8d0b943 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_debug.c
+++ b/drivers/gpu/drm/i915/i915_gem_debug.c
@@ -105,12 +105,14 @@ i915_dump_lru(struct drm_device *dev, const char *where)
        struct drm_i915_gem_object      *obj_priv;
 
        DRM_INFO("active list %s {\n", where);
+       spin_lock(&dev_priv->mm.active_list_lock);
        list_for_each_entry(obj_priv, &dev_priv->mm.active_list,
                            list)
        {
                DRM_INFO("    %p: %08x\n", obj_priv,
                         obj_priv->last_rendering_seqno);
        }
+       spin_unlock(&dev_priv->mm.active_list_lock);
        DRM_INFO("}\n");
        DRM_INFO("flushing list %s {\n", where);
        list_for_each_entry(obj_priv, &dev_priv->mm.flushing_list,

diff --git a/drivers/gpu/drm/i915/i915_gem_debugfs.c b/drivers/gpu/drm/i915/i915_gem_debugfs.c
index 455ec97..a1ac0c5 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_gem_debugfs.c
@@ -69,10 +69,13 @@ static int i915_gem_object_list_info(struct seq_file *m, void *data)
        struct drm_device *dev = node->minor->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj_priv;
+       spinlock_t *lock = NULL;
 
        switch (list) {
        case ACTIVE_LIST:
                seq_printf(m, "Active:\n");
+               lock = &dev_priv->mm.active_list_lock;
+               spin_lock(lock);
                head = &dev_priv->mm.active_list;
                break;
        case INACTIVE_LIST:
@@ -104,6 +107,9 @@ static int i915_gem_object_list_info(struct seq_file *m, void *data)
                        seq_printf(m, " (fence: %d\n", obj_priv->fence_reg);
                seq_printf(m, "\n");
        }
+
+       if (lock)
+           spin_unlock(lock);
        return 0;
 }