sched: Add interface for copying core scheduling cookie between two tasks

Orabug: 34152329

Signed-off-by: Boris Ostrovsky <[email protected]>
Reviewed-by: Libo Chen <[email protected]>
Reviewed-by: Chris Hyser <[email protected]>

Author: Boris Ostrovsky

include/linux/sched.h

@@ -2186,10 +2186,13 @@ extern void sched_core_fork(struct task_struct *p);
 extern int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type,
 				unsigned long uaddr);
 extern int sched_core_idle_cpu(int cpu);
+extern void sched_cs_copy(struct task_struct *src, struct task_struct *dst);
 #else
 static inline void sched_core_free(struct task_struct *tsk) { }
 static inline void sched_core_fork(struct task_struct *p) { }
 static inline int sched_core_idle_cpu(int cpu) { return idle_cpu(cpu); }
+static inline void sched_cs_copy(struct task_struct *src,
+				 struct task_struct *dst) { }
 #endif
 
 extern void sched_set_stop_task(int cpu, struct task_struct *stop);

kernel/sched/core_sched.c

@@ -125,6 +125,22 @@ static void __sched_core_set(struct task_struct *p, unsigned long cookie)
 	sched_core_put_cookie(cookie);
 }
 
+void sched_cs_copy(struct task_struct *src, struct task_struct *dst)
+{
+	unsigned long cookie;
+
+	get_task_struct(src);
+	get_task_struct(dst);
+
+	cookie = sched_core_clone_cookie(src);
+	__sched_core_set(dst, cookie);
+	sched_core_put_cookie(cookie);
+
+	put_task_struct(dst);
+	put_task_struct(src);
+}
+EXPORT_SYMBOL(sched_cs_copy);
+
 /* Called from prctl interface: PR_SCHED_CORE */
 int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type,
 			 unsigned long uaddr)