list: Split list_del() debug checking into separate function

[deliverable/linux.git] / include / linux / list.h

diff --git a/include/linux/list.h b/include/linux/list.h
index 5183138aa932da88c83177b9f8372bd9c3437e13..d1039ecaf94fdbea21a25c0fa4a5ea351683dd91 100644 (file)
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -28,27 +28,42 @@ static inline void INIT_LIST_HEAD(struct list_head *list)
        list->prev = list;
 }
 
+#ifdef CONFIG_DEBUG_LIST
+extern bool __list_add_valid(struct list_head *new,
+                             struct list_head *prev,
+                             struct list_head *next);
+extern bool __list_del_entry_valid(struct list_head *entry);
+#else
+static inline bool __list_add_valid(struct list_head *new,
+                               struct list_head *prev,
+                               struct list_head *next)
+{
+       return true;
+}
+static inline bool __list_del_entry_valid(struct list_head *entry)
+{
+       return true;
+}
+#endif
+
 /*
  * Insert a new entry between two known consecutive entries.
  *
  * This is only for internal list manipulation where we know
  * the prev/next entries already!
  */
-#ifndef CONFIG_DEBUG_LIST
 static inline void __list_add(struct list_head *new,
                              struct list_head *prev,
                              struct list_head *next)
 {
+       if (!__list_add_valid(new, prev, next))
+               return;
+
        next->prev = new;
        new->next = next;
        new->prev = prev;
        WRITE_ONCE(prev->next, new);
 }
-#else
-extern void __list_add(struct list_head *new,
-                             struct list_head *prev,
-                             struct list_head *next);
-#endif
 
 /**
  * list_add - add a new entry
@@ -96,22 +111,20 @@ static inline void __list_del(struct list_head * prev, struct list_head * next)
  * Note: list_empty() on entry does not return true after this, the entry is
  * in an undefined state.
  */
-#ifndef CONFIG_DEBUG_LIST
 static inline void __list_del_entry(struct list_head *entry)
 {
+       if (!__list_del_entry_valid(entry))
+               return;
+
        __list_del(entry->prev, entry->next);
 }
 
 static inline void list_del(struct list_head *entry)
 {
-       __list_del(entry->prev, entry->next);
+       __list_del_entry(entry);
        entry->next = LIST_POISON1;
        entry->prev = LIST_POISON2;
 }
-#else
-extern void __list_del_entry(struct list_head *entry);
-extern void list_del(struct list_head *entry);
-#endif
 
 /**
  * list_replace - replace old entry by new one
@@ -381,8 +394,11 @@ static inline void list_splice_tail_init(struct list_head *list,
  *
  * Note that if the list is empty, it returns NULL.
  */
-#define list_first_entry_or_null(ptr, type, member) \
-       (!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+#define list_first_entry_or_null(ptr, type, member) ({ \
+       struct list_head *head__ = (ptr); \
+       struct list_head *pos__ = READ_ONCE(head__->next); \
+       pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
+})
 
 /**
  * list_next_entry - get the next element in list