[PATCH 8/8] console: Use refcounts_t to track node references.

[Flavio Cruz]

* console/console.c (netfs_node_norefs): Use a soft reference to store
a node in dir_node, cons_node, disp_node, inp_node.
* console/console.c (netfs_try_dropping_softrefs): When dropping all
soft references remove node pointer from the fields above.
---
 console/console.c | 64 ++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 37 insertions(+), 27 deletions(-)

diff --git a/console/console.c b/console/console.c
index 57ae813..9c5869d 100644
--- a/console/console.c
+++ b/console/console.c
@@ -415,47 +415,51 @@ new_node (struct node **np, vcons_t vcons, 
vcons_node_type type)
 
 /* Node management.  */
 
-/* Node NP has no more references; free all its associated
-   storage.  */
+/* We need to drop the soft references on NP.  */
 void
-netfs_node_norefs (struct node *np)
+netfs_try_dropping_softrefs (struct node *np)
 {
   vcons_t vcons = np->nn->vcons;
+  int release = FALSE;
 
-  /* The root node does never go away.  */
-  assert (!np->nn->cons && np->nn->vcons);
-
-  /* Avoid deadlock.  */
-  pthread_spin_unlock (&netfs_node_refcnt_lock);
-
-  /* Find the back reference to ourself in the virtual console
-     structure, and delete it.  */
   pthread_mutex_lock (&vcons->lock);
-  pthread_spin_lock (&netfs_node_refcnt_lock);
-  if (np->references)
+  if (np == vcons->dir_node)
     {
-      /* Someone else got a reference while we were attempting to go
-        away.  This can happen in netfs_attempt_lookup.  In this
-        case, just unlock the node and do nothing else.  */
-      pthread_mutex_unlock (&vcons->lock);
-      pthread_mutex_unlock (&np->lock);
-      return;
+      release = TRUE;
+      vcons->dir_node = 0;
     }
-  if (np == vcons->dir_node)
-    vcons->dir_node = 0;
   else if (np == vcons->cons_node)
-    vcons->cons_node = 0;
+    {
+      release = TRUE;
+      vcons->cons_node = 0;
+    }
   else if (np == vcons->disp_node)
-    vcons->disp_node = 0;
-  else
     {
-      assert (np == vcons->inpt_node);
+      release = TRUE;
+      vcons->disp_node = 0;
+    }
+  else if (np == vcons->inpt_node)
+    {
+      release = TRUE;
       vcons->inpt_node = 0;
     }
+  if (release)
+    netfs_nrele_light (np);
   pthread_mutex_unlock (&vcons->lock);
 
   /* Release our reference.  */
-  vcons_release (vcons);
+  if (release)
+    vcons_release (vcons);
+
+}
+
+/* Node NP has no more references; free all its associated
+   storage.  */
+void
+netfs_node_norefs (struct node *np)
+{
+  /* The root node does never go away.  */
+  assert (!np->nn->cons && np->nn->vcons);
 
   free (np->nn);
   free (np);
@@ -634,7 +638,10 @@ netfs_attempt_lookup (struct iouser *user, struct node 
*dir,
             the virtual console.  */
          err = new_node (node, vcons, VCONS_NODE_DIR);
          if (!err)
-           vcons->dir_node = *node;
+            {
+              vcons->dir_node = *node;
+              netfs_nref_light (*node);
+            }
          else
            release_vcons = 1;
        }
@@ -663,6 +670,7 @@ netfs_attempt_lookup (struct iouser *user, struct node *dir,
              if (!err)
                {
                  vcons->cons_node = *node;
+                  netfs_nref_light (*node);
                  ref_vcons = 1;
                }
            }
@@ -682,6 +690,7 @@ netfs_attempt_lookup (struct iouser *user, struct node *dir,
              if (!err)
                {
                  vcons->disp_node = *node;
+                  netfs_nref_light (*node);
                  ref_vcons = 1;
                }
            }
@@ -701,6 +710,7 @@ netfs_attempt_lookup (struct iouser *user, struct node *dir,
              if (!err)
                {
                  vcons->inpt_node = *node;
+                  netfs_nref_light (*node);
                  ref_vcons = 1;
                }
            }
-- 
2.6.4