Changes in kernel/generic/src/mm/as.c [5df1963:826599a2] in mainline

File:

• kernel/generic/src/mm/as.c (modified) (13 diffs)

kernel/generic/src/mm/as.c

@@ -520 +520 @@
 }
 
+/** Remove reference to address space area share info.
+ *
+ * If the reference count drops to 0, the sh_info is deallocated.
+ *
+ * @param sh_info Pointer to address space area share info.
+ *
+ */
+NO_TRACE static void sh_info_remove_reference(share_info_t *sh_info)
+{
+        bool dealloc = false;
+        
+        mutex_lock(&sh_info->lock);
+        ASSERT(sh_info->refcount);
+        
+        if (--sh_info->refcount == 0) {
+                dealloc = true;
+                
+                /*
+                 * Now walk carefully the pagemap B+tree and free/remove
+                 * reference from all frames found there.
+                 */
+                list_foreach(sh_info->pagemap.leaf_list, leaf_link,
+                    btree_node_t, node) {
+                        btree_key_t i;
+                        
+                        for (i = 0; i < node->keys; i++)
+                                frame_free((uintptr_t) node->value[i], 1);
+                }
+                
+        }
+        mutex_unlock(&sh_info->lock);
+        
+        if (dealloc) {
+                if (sh_info->backend && sh_info->backend->destroy_shared_data) {
+                        sh_info->backend->destroy_shared_data(
+                            sh_info->backend_shared_data);
+                }
+                btree_destroy(&sh_info->pagemap);
+                free(sh_info);
+        }
+}
+
+
 /** Create address space area of common attributes.
  *
@@ -529 +572 @@
  * @param attrs        Attributes of the area.
  * @param backend      Address space area backend. NULL if no backend is used.
- * @param backend_data NULL or a pointer to an array holding two void *.
+ * @param backend_data NULL or a pointer to custom backend data.
  * @param base         Starting virtual address of the area.
  *                     If set to -1, a suitable mappable area is found.
@@ -566 +609 @@
         }
 
-        if (overflows_into_positive(*base, size))
+        if (overflows_into_positive(*base, size)) {
+                mutex_unlock(&as->lock);
                 return NULL;
+        }
 
         if (!check_area_conflicts(as, *base, pages, guarded, NULL)) {
@@ -584 +629 @@
         area->resident = 0;
         area->base = *base;
+        area->backend = backend;
         area->sh_info = NULL;
-        area->backend = backend;
         
         if (backend_data)
@@ -591 +636 @@
         else
                 memsetb(&area->backend_data, sizeof(area->backend_data), 0);
-        
+
+        share_info_t *si = NULL;
+
+        /*
+         * Create the sharing info structure.
+         * We do this in advance for every new area, even if it is not going
+         * to be shared.
+         */
+        if (!(attrs & AS_AREA_ATTR_PARTIAL)) {
+                si = (share_info_t *) malloc(sizeof(share_info_t), 0);
+                mutex_initialize(&si->lock, MUTEX_PASSIVE);
+                si->refcount = 1;
+                si->shared = false;
+                si->backend_shared_data = NULL;
+                si->backend = backend;
+                btree_create(&si->pagemap);
+
+                area->sh_info = si;
+        
+                if (area->backend && area->backend->create_shared_data) {
+                        if (!area->backend->create_shared_data(area)) {
+                                free(area);
+                                mutex_unlock(&as->lock);
+                                sh_info_remove_reference(si);
+                                return NULL;
+                        }
+                }
+        }
+
         if (area->backend && area->backend->create) {
                 if (!area->backend->create(area)) {
                         free(area);
                         mutex_unlock(&as->lock);
+                        if (!(attrs & AS_AREA_ATTR_PARTIAL))
+                                sh_info_remove_reference(si);
                         return NULL;
                 }
         }
-        
+
         btree_create(&area->used_space);
         btree_insert(&as->as_area_btree, *base, (void *) area,
@@ -709 +784 @@
         }
         
-        if (area->sh_info) {
+        mutex_lock(&area->sh_info->lock);
+        if (area->sh_info->shared) {
                 /*
                  * Remapping of shared address space areas
                  * is not supported.
                  */
+                mutex_unlock(&area->sh_info->lock);
                 mutex_unlock(&area->lock);
                 mutex_unlock(&as->lock);
                 return ENOTSUP;
         }
+        mutex_unlock(&area->sh_info->lock);
         
         size_t pages = SIZE2FRAMES((address - area->base) + size);
@@ -881 +959 @@
 }
 
-/** Remove reference to address space area share info.
- *
- * If the reference count drops to 0, the sh_info is deallocated.
- *
- * @param sh_info Pointer to address space area share info.
- *
- */
-NO_TRACE static void sh_info_remove_reference(share_info_t *sh_info)
-{
-        bool dealloc = false;
-        
-        mutex_lock(&sh_info->lock);
-        ASSERT(sh_info->refcount);
-        
-        if (--sh_info->refcount == 0) {
-                dealloc = true;
-                
-                /*
-                 * Now walk carefully the pagemap B+tree and free/remove
-                 * reference from all frames found there.
-                 */
-                list_foreach(sh_info->pagemap.leaf_list, leaf_link,
-                    btree_node_t, node) {
-                        btree_key_t i;
-                        
-                        for (i = 0; i < node->keys; i++)
-                                frame_free((uintptr_t) node->value[i], 1);
-                }
-                
-        }
-        mutex_unlock(&sh_info->lock);
-        
-        if (dealloc) {
-                btree_destroy(&sh_info->pagemap);
-                free(sh_info);
-        }
-}
-
 /** Destroy address space area.
  *
@@ -1000 +1040 @@
         area->attributes |= AS_AREA_ATTR_PARTIAL;
         
-        if (area->sh_info)
-                sh_info_remove_reference(area->sh_info);
+        sh_info_remove_reference(area->sh_info);
         
         mutex_unlock(&area->lock);
@@ -1088 +1127 @@
          */
         share_info_t *sh_info = src_area->sh_info;
-        if (!sh_info) {
-                sh_info = (share_info_t *) malloc(sizeof(share_info_t), 0);
-                mutex_initialize(&sh_info->lock, MUTEX_PASSIVE);
-                sh_info->refcount = 2;
-                btree_create(&sh_info->pagemap);
-                src_area->sh_info = sh_info;
-                
+        
+        mutex_lock(&sh_info->lock);
+        sh_info->refcount++;
+        bool shared = sh_info->shared;
+        sh_info->shared = true;
+        mutex_unlock(&sh_info->lock);
+
+        if (!shared) {
                 /*
                  * Call the backend to setup sharing.
+                 * This only happens once for each sh_info.
                  */
                 src_area->backend->share(src_area);
-        } else {
-                mutex_lock(&sh_info->lock);
-                sh_info->refcount++;
-                mutex_unlock(&sh_info->lock);
         }
         
@@ -1221 +1258 @@
         }
         
-        if ((area->sh_info) || (area->backend != &anon_backend)) {
-                /* Copying shared areas not supported yet */
+        if (area->backend != &anon_backend) {
                 /* Copying non-anonymous memory not supported yet */
                 mutex_unlock(&area->lock);
@@ -1228 +1264 @@
                 return ENOTSUP;
         }
+
+        mutex_lock(&area->sh_info->lock);
+        if (area->sh_info->shared) {
+                /* Copying shared areas not supported yet */
+                mutex_unlock(&area->sh_info->lock);
+                mutex_unlock(&area->lock);
+                mutex_unlock(&as->lock);
+                return ENOTSUP;
+        }
+        mutex_unlock(&area->sh_info->lock);
         
         /*
@@ -1679 +1725 @@
         ASSERT(count);
         
-        btree_node_t *leaf;
+        btree_node_t *leaf = NULL;
         size_t pages = (size_t) btree_search(&area->used_space, page, &leaf);
         if (pages) {
@@ -1687 +1733 @@
                 return false;
         }
+
+        ASSERT(leaf != NULL);
         
         if (!leaf->keys) {