sched: programmable: Add a tag for the task

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5KUFB
CVE: NA

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

Add a tag for the task, useful to identify the special task.
User can use the file system interface to mark different tags for
specific workloads.
The kernel subsystems can use the set_* helpers to mark it too.
The bpf prog obtains the tags to detect different workloads.
Signed-off-by: NChen Hui <judy.chenhui@huawei.com>
Signed-off-by: NRen Zhijie <renzhijie2@huawei.com>
Signed-off-by: NHui Tang <tanghui20@huawei.com>

include/linux/sched.h

@@ -1416,7 +1416,12 @@ struct task_struct {
 	KABI_RESERVE(4)
 	KABI_RESERVE(5)
 #endif
+#ifdef CONFIG_BPF_SCHED
+	/* Used to pad the tag of a task */
+	KABI_USE(6, long tag)
+#else
 	KABI_RESERVE(6)
+#endif
 	KABI_RESERVE(7)
 	KABI_RESERVE(8)
 	KABI_RESERVE(9)

init/init_task.c

@@ -216,6 +216,9 @@ struct task_struct init_task
 #endif
 #ifdef CONFIG_SECCOMP_FILTER
 	.seccomp	= { .filter_count = ATOMIC_INIT(0) },
+#endif
+#ifdef CONFIG_BPF_SCHED
+	.tag		= 0,
 #endif
 	._resvd = &init_task_struct_resvd,
 };

kernel/sched/core.c

@@ -3477,6 +3477,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
 #ifdef CONFIG_SMP
 	p->wake_entry.u_flags = CSD_TYPE_TTWU;
 #endif
+#ifdef CONFIG_BPF_SCHED
+	p->tag		= 0;
+#endif
 }
 
 DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);