From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>, Daniel Wagner <wagi@monom.org>,
Tom Zanussi <zanussi@kernel.org>,
"Srivatsa S. Bhat" <srivatsa@csail.mit.edu>,
stable@kernel.org,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: [PATCH RT 3/8] sched: Collate affine_move_task() stoppers
Date: Fri, 09 Jul 2021 17:59:56 -0400 [thread overview]
Message-ID: <20210709220017.632244614@goodmis.org> (raw)
In-Reply-To: 20210709215953.122804544@goodmis.org
5.10.47-rt46-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra <peterz@infradead.org>
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 d497b13efb53..6880c300c624 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2275,30 +2275,23 @@ 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)) {
--
2.30.2
next prev parent reply other threads:[~2021-07-09 22:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 21:59 [PATCH RT 0/8] Linux 5.10.47-rt46-rc1 Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 1/8] sched: Fix migration_cpu_stop() requeueing Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 2/8] sched: Simplify migration_cpu_stop() Steven Rostedt
2021-07-09 21:59 ` Steven Rostedt [this message]
2021-07-09 21:59 ` [PATCH RT 4/8] sched: Optimize migration_cpu_stop() Steven Rostedt
2021-07-09 21:59 ` [PATCH RT 5/8] sched: Fix affine_move_task() self-concurrency Steven Rostedt
2021-07-25 5:03 ` Pavel Machek
2021-07-26 13:39 ` Valentin Schneider
2021-07-26 16:07 ` Paul Gortmaker
2021-07-09 21:59 ` [PATCH RT 6/8] sched: Simplify set_affinity_pending refcounts Steven Rostedt
2021-07-09 22:00 ` [PATCH RT 7/8] sched: Dont defer CPU pick to migration_cpu_stop() Steven Rostedt
2021-07-09 22:00 ` [PATCH RT 8/8] Linux 5.10.47-rt46-rc1 Steven Rostedt
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