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From e62b758a0149648256ed0fa194d9e107e294d8aa Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 8 Jun 2021 00:37:32 -0400
Subject: [PATCH 291/323] sched: Collate affine_move_task() stoppers
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
commit 58b1a45086b5f80f2b2842aa7ed0da51a64a302b upstream.
The SCA_MIGRATE_ENABLE and task_running() cases are almost identical,
collapse them to avoid further duplication.
Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()")
Cc: stable@kernel.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210224131355.500108964@infradead.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/sched/core.c | 23 ++++++++---------------
1 file changed, 8 insertions(+), 15 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 31fa925852e5..3130289baf79 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2291,30 +2291,23 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag
return -EINVAL;
}
- if (flags & SCA_MIGRATE_ENABLE) {
-
- refcount_inc(&pending->refs); /* pending->{arg,stop_work} */
- p->migration_flags &= ~MDF_PUSH;
- task_rq_unlock(rq, p, rf);
-
- stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
- &pending->arg, &pending->stop_work);
-
- return 0;
- }
-
if (task_running(rq, p) || p->state == TASK_WAKING) {
/*
- * Lessen races (and headaches) by delegating
- * is_migration_disabled(p) checks to the stopper, which will
- * run on the same CPU as said p.
+ * MIGRATE_ENABLE gets here because 'p == current', but for
+ * anything else we cannot do is_migration_disabled(), punt
+ * and have the stopper function handle it all race-free.
*/
+
refcount_inc(&pending->refs); /* pending->{arg,stop_work} */
+ if (flags & SCA_MIGRATE_ENABLE)
+ p->migration_flags &= ~MDF_PUSH;
task_rq_unlock(rq, p, rf);
stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
&pending->arg, &pending->stop_work);
+ if (flags & SCA_MIGRATE_ENABLE)
+ return 0;
} else {
if (!is_migration_disabled(p)) {
--
2.43.0
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