merge task_work and rcu_head, get rid of separate allocation for keyring case

task_work and rcu_head are identical now; merge them (calling the result
struct callback_head, rcu_head #define'd to it), kill separate allocation
in security/keys since we can just use cred->rcu now.

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

3 files changed, 10 insertions, 15 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b9216ebc2789..af3555cc760f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1405,7 +1405,7 @@ struct task_struct {
         int (*notifier)(void *priv);
         void *notifier_data;
         sigset_t *notifier_mask;
-        void *task_works;
+        struct callback_head *task_works;
 
         struct audit_context *audit_context;
 #ifdef CONFIG_AUDITSYSCALL
diff --git a/include/linux/task_work.h b/include/linux/task_work.h
index 3b3e2c8d037b..fb46b03b1852 100644
--- a/include/linux/task_work.h
+++ b/include/linux/task_work.h
@@ -4,22 +4,16 @@
 #include <linux/list.h>
 #include <linux/sched.h>
 
-struct task_work;
-typedef void (*task_work_func_t)(struct task_work *);
-
-struct task_work {
-        struct task_work *next;
-        task_work_func_t func;
-};
+typedef void (*task_work_func_t)(struct callback_head *);
 
 static inline void
-init_task_work(struct task_work *twork, task_work_func_t func)
+init_task_work(struct callback_head *twork, task_work_func_t func)
 {
         twork->func = func;
 }
 
-int task_work_add(struct task_struct *task, struct task_work *twork, bool);
-struct task_work *task_work_cancel(struct task_struct *, task_work_func_t);
+int task_work_add(struct task_struct *task, struct callback_head *twork, bool);
+struct callback_head *task_work_cancel(struct task_struct *, task_work_func_t);
 void task_work_run(void);
 
 static inline void exit_task_work(struct task_struct *task)
diff --git a/include/linux/types.h b/include/linux/types.h
index 9c1bd539ea70..bf0dd7524b2a 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -246,14 +246,15 @@ struct ustat {
 };
 
 /**
- * struct rcu_head - callback structure for use with RCU
+ * struct callback_head - callback structure for use with RCU and task_work
  * @next: next update requests in a list
  * @func: actual update function to call after the grace period.
  */
-struct rcu_head {
-        struct rcu_head *next;
-        void (*func)(struct rcu_head *head);
+struct callback_head {
+        struct callback_head *next;
+        void (*func)(struct callback_head *head);
 };
+#define rcu_head callback_head
 
 #endif  /* __KERNEL__ */
 #endif /*  __ASSEMBLY__ */