1 files changed, 180 insertions, 64 deletions

diff --git a/kernel/gcov/fs.c b/kernel/gcov/fs.c
index ef3c3f88a7a3..f83972b16564 100644
--- a/kernel/gcov/fs.c
+++ b/kernel/gcov/fs.c
@@ -33,10 +33,11 @@
  * @children: child nodes
  * @all: list head for list of all nodes
  * @parent: parent node
- * @info: associated profiling data structure if not a directory
- * @ghost: when an object file containing profiling data is unloaded we keep a
- *         copy of the profiling data here to allow collecting coverage data
- *         for cleanup code. Such a node is called a "ghost".
+ * @loaded_info: array of pointers to profiling data sets for loaded object
+ *   files.
+ * @num_loaded: number of profiling data sets for loaded object files.
+ * @unloaded_info: accumulated copy of profiling data sets for unloaded
+ *   object files. Used only when gcov_persist=1.
  * @dentry: main debugfs entry, either a directory or data file
  * @links: associated symbolic links
  * @name: data file basename
@@ -51,10 +52,11 @@ struct gcov_node {
         struct list_head children;
         struct list_head all;
         struct gcov_node *parent;
-        struct gcov_info *info;
-        struct gcov_info *ghost;
+        struct gcov_info **loaded_info;
+        struct gcov_info *unloaded_info;
         struct dentry *dentry;
         struct dentry **links;
+        int num_loaded;
         char name[0];
 };
 
@@ -136,16 +138,37 @@ static const struct seq_operations gcov_seq_ops = {
 };
 
 /*
- * Return the profiling data set for a given node. This can either be the
- * original profiling data structure or a duplicate (also called "ghost")
- * in case the associated object file has been unloaded.
+ * Return a profiling data set associated with the given node. This is
+ * either a data set for a loaded object file or a data set copy in case
+ * all associated object files have been unloaded.
  */
 static struct gcov_info *get_node_info(struct gcov_node *node)
 {
-        if (node->info)
-                return node->info;
+        if (node->num_loaded > 0)
+                return node->loaded_info[0];
 
-        return node->ghost;
+        return node->unloaded_info;
+}
+
+/*
+ * Return a newly allocated profiling data set which contains the sum of
+ * all profiling data associated with the given node.
+ */
+static struct gcov_info *get_accumulated_info(struct gcov_node *node)
+{
+        struct gcov_info *info;
+        int i = 0;
+
+        if (node->unloaded_info)
+                info = gcov_info_dup(node->unloaded_info);
+        else
+                info = gcov_info_dup(node->loaded_info[i++]);
+        if (!info)
+                return NULL;
+        for (; i < node->num_loaded; i++)
+                gcov_info_add(info, node->loaded_info[i]);
+
+        return info;
 }
 
 /*
@@ -163,9 +186,10 @@ static int gcov_seq_open(struct inode *inode, struct file *file)
         mutex_lock(&node_lock);
         /*
          * Read from a profiling data copy to minimize reference tracking
-         * complexity and concurrent access.
+         * complexity and concurrent access and to keep accumulating multiple
+         * profiling data sets associated with one node simple.
          */
-        info = gcov_info_dup(get_node_info(node));
+        info = get_accumulated_info(node);
         if (!info)
                 goto out_unlock;
         iter = gcov_iter_new(info);
@@ -225,12 +249,25 @@ static struct gcov_node *get_node_by_name(const char *name)
         return NULL;
 }
 
+/*
+ * Reset all profiling data associated with the specified node.
+ */
+static void reset_node(struct gcov_node *node)
+{
+        int i;
+
+        if (node->unloaded_info)
+                gcov_info_reset(node->unloaded_info);
+        for (i = 0; i < node->num_loaded; i++)
+                gcov_info_reset(node->loaded_info[i]);
+}
+
 static void remove_node(struct gcov_node *node);
 
 /*
  * write() implementation for gcov data files. Reset profiling data for the
- * associated file. If the object file has been unloaded (i.e. this is
- * a "ghost" node), remove the debug fs node as well.
+ * corresponding file. If all associated object files have been unloaded,
+ * remove the debug fs node as well.
  */
 static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
                               size_t len, loff_t *pos)
@@ -245,10 +282,10 @@ static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
         node = get_node_by_name(info->filename);
         if (node) {
                 /* Reset counts or remove node for unloaded modules. */
-                if (node->ghost)
+                if (node->num_loaded == 0)
                         remove_node(node);
                 else
-                        gcov_info_reset(node->info);
+                        reset_node(node);
         }
         /* Reset counts for open file. */
         gcov_info_reset(info);
@@ -378,7 +415,10 @@ static void init_node(struct gcov_node *node, struct gcov_info *info,
         INIT_LIST_HEAD(&node->list);
         INIT_LIST_HEAD(&node->children);
         INIT_LIST_HEAD(&node->all);
-        node->info = info;
+        if (node->loaded_info) {
+                node->loaded_info[0] = info;
+                node->num_loaded = 1;
+        }
         node->parent = parent;
         if (name)
                 strcpy(node->name, name);
@@ -394,9 +434,13 @@ static struct gcov_node *new_node(struct gcov_node *parent,
         struct gcov_node *node;
 
         node = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
-        if (!node) {
-                pr_warning("out of memory\n");
-                return NULL;
+        if (!node)
+                goto err_nomem;
+        if (info) {
+                node->loaded_info = kcalloc(1, sizeof(struct gcov_info *),
+                                           GFP_KERNEL);
+                if (!node->loaded_info)
+                        goto err_nomem;
         }
         init_node(node, info, name, parent);
         /* Differentiate between gcov data file nodes and directory nodes. */
@@ -416,6 +460,11 @@ static struct gcov_node *new_node(struct gcov_node *parent,
         list_add(&node->all, &all_head);
 
         return node;
+
+err_nomem:
+        kfree(node);
+        pr_warning("out of memory\n");
+        return NULL;
 }
 
 /* Remove symbolic links associated with node. */
@@ -441,8 +490,9 @@ static void release_node(struct gcov_node *node)
         list_del(&node->all);
         debugfs_remove(node->dentry);
         remove_links(node);
-        if (node->ghost)
-                gcov_info_free(node->ghost);
+        kfree(node->loaded_info);
+        if (node->unloaded_info)
+                gcov_info_free(node->unloaded_info);
         kfree(node);
 }
 
@@ -477,7 +527,7 @@ static struct gcov_node *get_child_by_name(struct gcov_node *parent,
 
 /*
  * write() implementation for reset file. Reset all profiling data to zero
- * and remove ghost nodes.
+ * and remove nodes for which all associated object files are unloaded.
  */
 static ssize_t reset_write(struct file *file, const char __user *addr,
                            size_t len, loff_t *pos)
@@ -487,8 +537,8 @@ static ssize_t reset_write(struct file *file, const char __user *addr,
         mutex_lock(&node_lock);
 restart:
         list_for_each_entry(node, &all_head, all) {
-                if (node->info)
-                        gcov_info_reset(node->info);
+                if (node->num_loaded > 0)
+                        reset_node(node);
                 else if (list_empty(&node->children)) {
                         remove_node(node);
                         /* Several nodes may have gone - restart loop. */
@@ -564,37 +614,115 @@ err_remove:
 }
 
 /*
- * The profiling data set associated with this node is being unloaded. Store a
- * copy of the profiling data and turn this node into a "ghost".
+ * Associate a profiling data set with an existing node. Needs to be called
+ * with node_lock held.
  */
-static int ghost_node(struct gcov_node *node)
+static void add_info(struct gcov_node *node, struct gcov_info *info)
 {
-        node->ghost = gcov_info_dup(node->info);
-        if (!node->ghost) {
-                pr_warning("could not save data for '%s' (out of memory)\n",
-                           node->info->filename);
-                return -ENOMEM;
+        struct gcov_info **loaded_info;
+        int num = node->num_loaded;
+
+        /*
+         * Prepare new array. This is done first to simplify cleanup in
+         * case the new data set is incompatible, the node only contains
+         * unloaded data sets and there's not enough memory for the array.
+         */
+        loaded_info = kcalloc(num + 1, sizeof(struct gcov_info *), GFP_KERNEL);
+        if (!loaded_info) {
+                pr_warning("could not add '%s' (out of memory)\n",
+                           info->filename);
+                return;
+        }
+        memcpy(loaded_info, node->loaded_info,
+               num * sizeof(struct gcov_info *));
+        loaded_info[num] = info;
+        /* Check if the new data set is compatible. */
+        if (num == 0) {
+                /*
+                 * A module was unloaded, modified and reloaded. The new
+                 * data set replaces the copy of the last one.
+                 */
+                if (!gcov_info_is_compatible(node->unloaded_info, info)) {
+                        pr_warning("discarding saved data for %s "
+                                   "(incompatible version)\n", info->filename);
+                        gcov_info_free(node->unloaded_info);
+                        node->unloaded_info = NULL;
+                }
+        } else {
+                /*
+                 * Two different versions of the same object file are loaded.
+                 * The initial one takes precedence.
+                 */
+                if (!gcov_info_is_compatible(node->loaded_info[0], info)) {
+                        pr_warning("could not add '%s' (incompatible "
+                                   "version)\n", info->filename);
+                        kfree(loaded_info);
+                        return;
+                }
         }
-        node->info = NULL;
+        /* Overwrite previous array. */
+        kfree(node->loaded_info);
+        node->loaded_info = loaded_info;
+        node->num_loaded = num + 1;
+}
 
-        return 0;
+/*
+ * Return the index of a profiling data set associated with a node.
+ */
+static int get_info_index(struct gcov_node *node, struct gcov_info *info)
+{
+        int i;
+
+        for (i = 0; i < node->num_loaded; i++) {
+                if (node->loaded_info[i] == info)
+                        return i;
+        }
+        return -ENOENT;
 }
 
 /*
- * Profiling data for this node has been loaded again. Add profiling data
- * from previous instantiation and turn this node into a regular node.
+ * Save the data of a profiling data set which is being unloaded.
  */
-static void revive_node(struct gcov_node *node, struct gcov_info *info)
+static void save_info(struct gcov_node *node, struct gcov_info *info)
 {
-        if (gcov_info_is_compatible(node->ghost, info))
-                gcov_info_add(info, node->ghost);
+        if (node->unloaded_info)
+                gcov_info_add(node->unloaded_info, info);
         else {
-                pr_warning("discarding saved data for '%s' (version changed)\n",
+                node->unloaded_info = gcov_info_dup(info);
+                if (!node->unloaded_info) {
+                        pr_warning("could not save data for '%s' "
+                                   "(out of memory)\n", info->filename);
+                }
+        }
+}
+
+/*
+ * Disassociate a profiling data set from a node. Needs to be called with
+ * node_lock held.
+ */
+static void remove_info(struct gcov_node *node, struct gcov_info *info)
+{
+        int i;
+
+        i = get_info_index(node, info);
+        if (i < 0) {
+                pr_warning("could not remove '%s' (not found)\n",
                            info->filename);
+                return;
         }
-        gcov_info_free(node->ghost);
-        node->ghost = NULL;
-        node->info = info;
+        if (gcov_persist)
+                save_info(node, info);
+        /* Shrink array. */
+        node->loaded_info[i] = node->loaded_info[node->num_loaded - 1];
+        node->num_loaded--;
+        if (node->num_loaded > 0)
+                return;
+        /* Last loaded data set was removed. */
+        kfree(node->loaded_info);
+        node->loaded_info = NULL;
+        node->num_loaded = 0;
+        if (!node->unloaded_info)
+                remove_node(node);
 }
 
 /*
@@ -609,30 +737,18 @@ void gcov_event(enum gcov_action action, struct gcov_info *info)
         node = get_node_by_name(info->filename);
         switch (action) {
         case GCOV_ADD:
-                /* Add new node or revive ghost. */
-                if (!node) {
+                if (node)
+                        add_info(node, info);
+                else
                         add_node(info);
-                        break;
-                }
-                if (gcov_persist)
-                        revive_node(node, info);
-                else {
-                        pr_warning("could not add '%s' (already exists)\n",
-                                   info->filename);
-                }
                 break;
         case GCOV_REMOVE:
-                /* Remove node or turn into ghost. */
-                if (!node) {
+                if (node)
+                        remove_info(node, info);
+                else {
                         pr_warning("could not remove '%s' (not found)\n",
                                    info->filename);
-                        break;
                 }
-                if (gcov_persist) {
-                        if (!ghost_node(node))
-                                break;
-                }
-                remove_node(node);
                 break;
         }
         mutex_unlock(&node_lock);