linux-kernel - [PATCH 1/3] sched: Add new API wake_up_if

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 15 Aug 2014 15:01:23 +0800
From:	Chuansheng Liu <chuansheng.liu@...el.com>
To:	peterz@...radead.org, luto@...capital.net,
	daniel.lezcano@...aro.org, rjw@...ysocki.net, mingo@...hat.com
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	changcheng.liu@...el.com, xiaoming.wang@...el.com,
	souvik.k.chakravarty@...el.com,
	Chuansheng Liu <chuansheng.liu@...el.com>
Subject: [PATCH 1/3] sched: Add new API wake_up_if_idle() to wake up the idle cpu

Implementing one new API wake_up_if_idle(), which is used to
wake up the idle CPU.

Suggested-by: Andy Lutomirski <luto@...capital.net>
Signed-off-by: Chuansheng Liu <chuansheng.liu@...el.com>
---
 include/linux/sched.h |    1 +
 kernel/sched/core.c   |   16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 857ba40..3f89ac1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1024,6 +1024,7 @@ struct sched_domain_topology_level {
 extern struct sched_domain_topology_level *sched_domain_topology;
 
 extern void set_sched_topology(struct sched_domain_topology_level *tl);
+extern void wake_up_if_idle(int cpu);
 
 #ifdef CONFIG_SCHED_DEBUG
 # define SD_INIT_NAME(type)		.name = #type
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1211575..adf104f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1620,6 +1620,22 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu)
 	}
 }
 
+void wake_up_if_idle(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	unsigned long flags;
+
+	if (set_nr_if_polling(rq->idle)) {
+		trace_sched_wake_idle_without_ipi(cpu);
+	} else {
+		raw_spin_lock_irqsave(&rq->lock, flags);
+		if (rq->curr == rq->idle)
+			smp_send_reschedule(cpu);
+		/* Else cpu is not in idle, do nothing here */
+		raw_spin_unlock_irqrestore(&rq->lock, flags);
+	}
+}
+
 bool cpus_share_cache(int this_cpu, int that_cpu)
 {
 	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/