[PATCH v8 -tip 21/26] sched: Handle task addition to CGroup

[Joel Fernandes (Google)]

Due to earlier patches, the old way of computing a task's cookie when it
is added to a CGroup,is outdated. Update it by fetching the group's
cookie using the new helpers.

Tested-by: Julien Desfossez <jdesfos...@digitalocean.com>
Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org>
---
 kernel/sched/core.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 61e1dcf11000..1321c26a8385 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8505,6 +8505,9 @@ void sched_offline_group(struct task_group *tg)
        spin_unlock_irqrestore(&task_group_lock, flags);
 }
 
+#define SCHED_CORE_GROUP_COOKIE_MASK ((1UL << (sizeof(unsigned long) * 4)) - 1)
+static unsigned long cpu_core_get_group_cookie(struct task_group *tg);
+
 static void sched_change_group(struct task_struct *tsk, int type)
 {
        struct task_group *tg;
@@ -8519,11 +8522,13 @@ static void sched_change_group(struct task_struct *tsk, 
int type)
        tg = autogroup_task_group(tsk, tg);
 
 #ifdef CONFIG_SCHED_CORE
-       if ((unsigned long)tsk->sched_task_group == tsk->core_cookie)
-               tsk->core_cookie = 0UL;
+       if (tsk->core_group_cookie) {
+               tsk->core_group_cookie = 0UL;
+               tsk->core_cookie &= ~SCHED_CORE_GROUP_COOKIE_MASK;
+       }
 
-       if (tg->core_tagged /* && !tsk->core_cookie ? */)
-               tsk->core_cookie = (unsigned long)tg;
+       tsk->core_group_cookie = cpu_core_get_group_cookie(tg);
+       tsk->core_cookie |= tsk->core_group_cookie;
 #endif
 
        tsk->sched_task_group = tg;
@@ -9471,7 +9476,7 @@ static unsigned long cpu_core_get_group_cookie(struct 
task_group *tg)
 
                if (tg->core_tagged) {
                        unsigned long cookie = ((unsigned long)tg << 8) | color;
-                       cookie &= (1UL << (sizeof(unsigned long) * 4)) - 1;
+                       cookie &= SCHED_CORE_GROUP_COOKIE_MASK;
                        return cookie;
                }
        }
-- 
2.29.0.rc1.297.gfa9743e501-goog