Merge tag 'trace-fixes-3.11-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Oleg Nesterov has been working hard in closing all the holes that can
  lead to race conditions between deleting an event and accessing an
  event debugfs file.  This included a fix to the debugfs system (acked
  by Greg Kroah-Hartman).  We think that all the holes have been patched
  and hopefully we don't find more.  I haven't marked all of them for
  stable because I need to examine them more to figure out how far back
  some of the changes need to go.

  Along the way, some other fixes have been made.  Alexander Z Lam fixed
  some logic where the wrong buffer was being modifed.

  Andrew Vagin found a possible corruption for machines that actually
  allocate cpumask, as a reference to one was being zeroed out by
  mistake.

  Dhaval Giani found a bad prototype when tracing is not configured.

  And I not only had some changes to help Oleg, but also finally fixed a
  long standing bug that Dave Jones and others have been hitting, where
  a module unload and reload can cause the function tracing accounting
  to get screwed up"

* tag 'trace-fixes-3.11-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix reset of time stamps during trace_clock changes
  tracing: Make TRACE_ITER_STOP_ON_FREE stop the correct buffer
  tracing: Fix trace_dump_stack() proto when CONFIG_TRACING is not set
  tracing: Fix fields of struct trace_iterator that are zeroed by mistake
  tracing/uprobes: Fail to unregister if probe event files are in use
  tracing/kprobes: Fail to unregister if probe event files are in use
  tracing: Add comment to describe special break case in probe_remove_event_call()
  tracing: trace_remove_event_call() should fail if call/file is in use
  debugfs: debugfs_remove_recursive() must not rely on list_empty(d_subdirs)
  ftrace: Check module functions being traced on reload
  ftrace: Consolidate some duplicate code for updating ftrace ops
  tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
  tracing: Introduce remove_event_file_dir()
  tracing: Change f_start() to take event_mutex and verify i_private != NULL
  tracing: Change event_filter_read/write to verify i_private != NULL
  tracing: Change event_enable/disable_read() to verify i_private != NULL
  tracing: Turn event/id->i_private into call->event.type

1 files changed, 22 insertions, 47 deletions

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 4888cb3fdef7..c7c83ff0f752 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -533,8 +533,7 @@ EXPORT_SYMBOL_GPL(debugfs_remove);
  */
 void debugfs_remove_recursive(struct dentry *dentry)
 {
-        struct dentry *child;
-        struct dentry *parent;
+        struct dentry *child, *next, *parent;
 
         if (IS_ERR_OR_NULL(dentry))
                 return;
@@ -544,61 +543,37 @@ void debugfs_remove_recursive(struct dentry *dentry)
                 return;
 
         parent = dentry;
+ down:
         mutex_lock(&parent->d_inode->i_mutex);
+        list_for_each_entry_safe(child, next, &parent->d_subdirs, d_u.d_child) {
+                if (!debugfs_positive(child))
+                        continue;
 
-        while (1) {
-                /*
-                 * When all dentries under "parent" has been removed,
-                 * walk up the tree until we reach our starting point.
-                 */
-                if (list_empty(&parent->d_subdirs)) {
-                        mutex_unlock(&parent->d_inode->i_mutex);
-                        if (parent == dentry)
-                                break;
-                        parent = parent->d_parent;
-                        mutex_lock(&parent->d_inode->i_mutex);
-                }
-                child = list_entry(parent->d_subdirs.next, struct dentry,
-                                d_u.d_child);
- next_sibling:
-
-                /*
-                 * If "child" isn't empty, walk down the tree and
-                 * remove all its descendants first.
-                 */
+                /* perhaps simple_empty(child) makes more sense */
                 if (!list_empty(&child->d_subdirs)) {
                         mutex_unlock(&parent->d_inode->i_mutex);
                         parent = child;
-                        mutex_lock(&parent->d_inode->i_mutex);
-                        continue;
+                        goto down;
                 }
-                __debugfs_remove(child, parent);
-                if (parent->d_subdirs.next == &child->d_u.d_child) {
-                        /*
-                         * Try the next sibling.
-                         */
-                        if (child->d_u.d_child.next != &parent->d_subdirs) {
-                                child = list_entry(child->d_u.d_child.next,
-                                                   struct dentry,
-                                                   d_u.d_child);
-                                goto next_sibling;
-                        }
-
-                        /*
-                         * Avoid infinite loop if we fail to remove
-                         * one dentry.
-                         */
-                        mutex_unlock(&parent->d_inode->i_mutex);
-                        break;
-                }
-                simple_release_fs(&debugfs_mount, &debugfs_mount_count);
+ up:
+                if (!__debugfs_remove(child, parent))
+                        simple_release_fs(&debugfs_mount, &debugfs_mount_count);
         }
 
-        parent = dentry->d_parent;
+        mutex_unlock(&parent->d_inode->i_mutex);
+        child = parent;
+        parent = parent->d_parent;
         mutex_lock(&parent->d_inode->i_mutex);
-        __debugfs_remove(dentry, parent);
+
+        if (child != dentry) {
+                next = list_entry(child->d_u.d_child.next, struct dentry,
+                                        d_u.d_child);
+                goto up;
+        }
+
+        if (!__debugfs_remove(child, parent))
+                simple_release_fs(&debugfs_mount, &debugfs_mount_count);
         mutex_unlock(&parent->d_inode->i_mutex);
-        simple_release_fs(&debugfs_mount, &debugfs_mount_count);
 }
 EXPORT_SYMBOL_GPL(debugfs_remove_recursive);