1 files changed, 21 insertions, 14 deletions

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 085197bd8812..70e8e21c0a30 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -59,29 +59,36 @@ struct files_struct {
         struct file __rcu * fd_array[NR_OPEN_DEFAULT];
 };
 
-#define rcu_dereference_check_fdtable(files, fdtfd) \
-        (rcu_dereference_check((fdtfd), \
-                               lockdep_is_held(&(files)->file_lock) || \
-                               atomic_read(&(files)->count) == 1 || \
-                               rcu_my_thread_group_empty()))
-
-#define files_fdtable(files) \
-                (rcu_dereference_check_fdtable((files), (files)->fdt))
-
 struct file_operations;
 struct vfsmount;
 struct dentry;
 
 extern void __init files_defer_init(void);
 
-static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
+#define rcu_dereference_check_fdtable(files, fdtfd) \
+        rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
+
+#define files_fdtable(files) \
+        rcu_dereference_check_fdtable((files), (files)->fdt)
+
+/*
+ * The caller must ensure that fd table isn't shared or hold rcu or file lock
+ */
+static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
 {
-        struct file * file = NULL;
-        struct fdtable *fdt = files_fdtable(files);
+        struct fdtable *fdt = rcu_dereference_raw(files->fdt);
 
         if (fd < fdt->max_fds)
-                file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
-        return file;
+                return rcu_dereference_raw(fdt->fd[fd]);
+        return NULL;
+}
+
+static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
+{
+        rcu_lockdep_assert(rcu_read_lock_held() ||
+                           lockdep_is_held(&files->file_lock),
+                           "suspicious rcu_dereference_check() usage");
+        return __fcheck_files(files, fd);
 }
 
 /*