[PATCH 3.2 73/74] sched: add macros to define bitops for task atomic flags

[Ben Hutchings]

3.2.94-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Zefan Li <lizefan@xxxxxxxxxx>

commit e0e5070b20e01f0321f97db4e4e174f3f6b49e50 upstream.

This will simplify code when we add new flags.

v3:
- Kees pointed out that no_new_privs should never be cleared, so we
shouldn't define task_clear_no_new_privs(). we define 3 macros instead
of a single one.

v2:
- updated scripts/tags.sh, suggested by Peter

Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Miao Xie <miaox@xxxxxxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
[lizf: Backported to 3.4:
 - adjust context
 - remove no_new_priv code
 - add atomic_flags to struct task_struct]
[bwh: Backported to 3.2:
 - Drop changes in scripts/tags.sh
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1313,6 +1313,8 @@ struct task_struct {
 	unsigned sched_reset_on_fork:1;
 	unsigned sched_contributes_to_load:1;
 
+	unsigned long atomic_flags; /* Flags needing atomic access. */
+
 	pid_t pid;
 	pid_t tgid;
 
@@ -1844,6 +1846,18 @@ extern void thread_group_times(struct ta
 #define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
 #define used_math() tsk_used_math(current)
 
+/* Per-process atomic flags. */
+
+#define TASK_PFA_TEST(name, func)					\
+	static inline bool task_##func(struct task_struct *p)		\
+	{ return test_bit(PFA_##name, &p->atomic_flags); }
+#define TASK_PFA_SET(name, func)					\
+	static inline void task_set_##func(struct task_struct *p)	\
+	{ set_bit(PFA_##name, &p->atomic_flags); }
+#define TASK_PFA_CLEAR(name, func)					\
+	static inline void task_clear_##func(struct task_struct *p)	\
+	{ clear_bit(PFA_##name, &p->atomic_flags); }
+
 /*
  * task->jobctl flags
  */