fix rcu annotations noise in cred.h
Al Viro [Sun, 7 Aug 2011 17:55:11 +0000 (18:55 +0100)]
task->cred is declared as __rcu, and access to other tasks' ->cred is,
indeed, protected.  Access to current->cred does not need rcu_dereference()
at all, since only the task itself can change its ->cred.  sparse, of
course, has no way of knowing that...

Add force-cast in current_cred(), make current_fsuid() et.al. use it.

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

include/linux/cred.h

index 48e82af..98f46ef 100644 (file)
@@ -265,10 +265,11 @@ static inline void put_cred(const struct cred *_cred)
 /**
  * current_cred - Access the current task's subjective credentials
  *
- * Access the subjective credentials of the current task.
+ * Access the subjective credentials of the current task.  RCU-safe,
+ * since nobody else can modify it.
  */
 #define current_cred() \
-       (current->cred)
+       (*(__force struct cred **)&current->cred)
 
 /**
  * __task_cred - Access a task's objective credentials
@@ -307,7 +308,7 @@ static inline void put_cred(const struct cred *_cred)
 ({                                                     \
        struct user_struct *__u;                        \
        struct cred *__cred;                            \
-       __cred = (struct cred *) current_cred();        \
+       __cred = current_cred();                        \
        __u = get_uid(__cred->user);                    \
        __u;                                            \
 })
@@ -322,7 +323,7 @@ static inline void put_cred(const struct cred *_cred)
 ({                                                     \
        struct group_info *__groups;                    \
        struct cred *__cred;                            \
-       __cred = (struct cred *) current_cred();        \
+       __cred = current_cred();                        \
        __groups = get_group_info(__cred->group_info);  \
        __groups;                                       \
 })
@@ -341,7 +342,7 @@ static inline void put_cred(const struct cred *_cred)
 
 #define current_cred_xxx(xxx)                  \
 ({                                             \
-       current->cred->xxx;                     \
+       current_cred()->xxx;                    \
 })
 
 #define current_uid()          (current_cred_xxx(uid))