linux-kernel - [RFC][PATCH 2/7] sched: Fix try_invoke_on_locked_down

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Message-ID: <20200827161754.300260291@infradead.org>
Date:   Thu, 27 Aug 2020 18:12:39 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org, mhiramat@...nel.org
Cc:     Eddy_Wu@...ndmicro.com, x86@...nel.org, davem@...emloft.net,
        rostedt@...dmis.org, naveen.n.rao@...ux.ibm.com,
        anil.s.keshavamurthy@...el.com, linux-arch@...r.kernel.org,
        cameron@...dycamel.com, oleg@...hat.com, will@...nel.org,
        paulmck@...nel.org, peterz@...radead.org
Subject: [RFC][PATCH 2/7] sched: Fix try_invoke_on_locked_down_task() semantics


Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/core.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3006,15 +3006,14 @@ try_to_wake_up(struct task_struct *p, un
  */
 bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
 {
-	bool ret = false;
 	struct rq_flags rf;
+	bool ret = false;
 	struct rq *rq;
 
-	lockdep_assert_irqs_enabled();
-	raw_spin_lock_irq(&p->pi_lock);
+	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
 	if (p->on_rq) {
 		rq = __task_rq_lock(p, &rf);
-		if (task_rq(p) == rq)
+		if (task_rq(p) == rq && rq->curr != p)
 			ret = func(p, arg);
 		rq_unlock(rq, &rf);
 	} else {
@@ -3028,7 +3027,7 @@ bool try_invoke_on_locked_down_task(stru
 				ret = func(p, arg);
 		}
 	}
-	raw_spin_unlock_irq(&p->pi_lock);
+	raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
 	return ret;
 }