procfs: add proc_remove_subtree()

just what it sounds like; do that only to procfs subtrees you've
created - doing that to something shared with another driver is
not only antisocial, but might cause interesting races with
proc_create() and its ilk.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 4b3b3ffb52f14e234aa3ec99abde281ca41e1817..21e1a8f1659d097f455e196d0b775771d3904b2b 100644 (file)
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -755,37 +755,8 @@ void pde_put(struct proc_dir_entry *pde)
                free_proc_entry(pde);
 }
 
-/*
- * Remove a /proc entry and free it if it's not currently in use.
- */
-void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
+static void entry_rundown(struct proc_dir_entry *de)
 {
-       struct proc_dir_entry **p;
-       struct proc_dir_entry *de = NULL;
-       const char *fn = name;
-       unsigned int len;
-
-       spin_lock(&proc_subdir_lock);
-       if (__xlate_proc_name(name, &parent, &fn) != 0) {
-               spin_unlock(&proc_subdir_lock);
-               return;
-       }
-       len = strlen(fn);
-
-       for (p = &parent->subdir; *p; p=&(*p)->next ) {
-               if (proc_match(len, fn, *p)) {
-                       de = *p;
-                       *p = de->next;
-                       de->next = NULL;
-                       break;
-               }
-       }
-       spin_unlock(&proc_subdir_lock);
-       if (!de) {
-               WARN(1, "name '%s'\n", name);
-               return;
-       }
-
        spin_lock(&de->pde_unload_lock);
        /*
         * Stop accepting new callers into module. If you're
@@ -817,6 +788,40 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
                spin_lock(&de->pde_unload_lock);
        }
        spin_unlock(&de->pde_unload_lock);
+}
+
+/*
+ * Remove a /proc entry and free it if it's not currently in use.
+ */
+void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
+{
+       struct proc_dir_entry **p;
+       struct proc_dir_entry *de = NULL;
+       const char *fn = name;
+       unsigned int len;
+
+       spin_lock(&proc_subdir_lock);
+       if (__xlate_proc_name(name, &parent, &fn) != 0) {
+               spin_unlock(&proc_subdir_lock);
+               return;
+       }
+       len = strlen(fn);
+
+       for (p = &parent->subdir; *p; p=&(*p)->next ) {
+               if (proc_match(len, fn, *p)) {
+                       de = *p;
+                       *p = de->next;
+                       de->next = NULL;
+                       break;
+               }
+       }
+       spin_unlock(&proc_subdir_lock);
+       if (!de) {
+               WARN(1, "name '%s'\n", name);
+               return;
+       }
+
+       entry_rundown(de);
 
        if (S_ISDIR(de->mode))
                parent->nlink--;
@@ -827,3 +832,57 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
        pde_put(de);
 }
 EXPORT_SYMBOL(remove_proc_entry);
+
+int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
+{
+       struct proc_dir_entry **p;
+       struct proc_dir_entry *root = NULL, *de, *next;
+       const char *fn = name;
+       unsigned int len;
+
+       spin_lock(&proc_subdir_lock);
+       if (__xlate_proc_name(name, &parent, &fn) != 0) {
+               spin_unlock(&proc_subdir_lock);
+               return -ENOENT;
+       }
+       len = strlen(fn);
+
+       for (p = &parent->subdir; *p; p=&(*p)->next ) {
+               if (proc_match(len, fn, *p)) {
+                       root = *p;
+                       *p = root->next;
+                       root->next = NULL;
+                       break;
+               }
+       }
+       if (!root) {
+               spin_unlock(&proc_subdir_lock);
+               return -ENOENT;
+       }
+       de = root;
+       while (1) {
+               next = de->subdir;
+               if (next) {
+                       de->subdir = next->next;
+                       next->next = NULL;
+                       de = next;
+                       continue;
+               }
+               spin_unlock(&proc_subdir_lock);
+
+               entry_rundown(de);
+               next = de->parent;
+               if (S_ISDIR(de->mode))
+                       next->nlink--;
+               de->nlink = 0;
+               if (de == root)
+                       break;
+               pde_put(de);
+
+               spin_lock(&proc_subdir_lock);
+               de = next;
+       }
+       pde_put(root);
+       return 0;
+}
+EXPORT_SYMBOL(remove_proc_subtree);

diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 8307f2f94d860f46139b6a20d6795a9186704c19..94dfb2aa5533c3c6a2a661358a6da4c6555310d3 100644 (file)
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -117,6 +117,7 @@ struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
                                const struct file_operations *proc_fops,
                                void *data);
 extern void remove_proc_entry(const char *name, struct proc_dir_entry *parent);
+extern int remove_proc_subtree(const char *name, struct proc_dir_entry *parent);
 
 struct pid_namespace;
 
@@ -202,6 +203,7 @@ static inline struct proc_dir_entry *proc_create_data(const char *name,
        return NULL;
 }
 #define remove_proc_entry(name, parent) do {} while (0)
+#define remove_proc_subtree(name, parent) do {} while (0)
 
 static inline struct proc_dir_entry *proc_symlink(const char *name,
                struct proc_dir_entry *parent,const char *dest) {return NULL;}