Re: [ANNOUNCE] 3.18.7-rt1

[Daniel Wagner <wagi@monom.org>]

Hi Sebastian,

On 02/16/2015 12:18 PM, Sebastian Andrzej Siewior wrote:
> Dear RT folks!
> 
> I'm pleased to announce the v3.18.7-rt1 patch set. It was running over
> the weekend on my x86 box and was still alive this morning. However it
> is still the first release for the v3.18 -RT series.
> I haven't follow the mailing list or commented / applied any patches
> from the list for -RT while being busy getting this release done (except
> one patch I needed to have anyway). This is about to change. I will try to
> go through my RT-inbox before doing the next release.

I needed the patch below to get it running stable under load on my shiny box.

cheers,
daniel


>From c517743659575932d7b7c94a08276d0cee8a2fdd Mon Sep 17 00:00:00 2001
From: Daniel Wagner <daniel.wagner@bmw-carit.de>
Date: Fri, 11 Jul 2014 15:26:13 +0200
Subject: [PATCH] thermal: Defer thermal wakups to threads

On RT the spin lock in pkg_temp_thermal_platfrom_thermal_notify will
call schedule while we run in irq context.

[<ffffffff816850ac>] dump_stack+0x4e/0x8f
[<ffffffff81680f7d>] __schedule_bug+0xa6/0xb4
[<ffffffff816896b4>] __schedule+0x5b4/0x700
[<ffffffff8168982a>] schedule+0x2a/0x90
[<ffffffff8168a8b5>] rt_spin_lock_slowlock+0xe5/0x2d0
[<ffffffff8168afd5>] rt_spin_lock+0x25/0x30
[<ffffffffa03a7b75>] pkg_temp_thermal_platform_thermal_notify+0x45/0x134 [x86_pkg_temp_thermal]
[<ffffffff8103d4db>] ? therm_throt_process+0x1b/0x160
[<ffffffff8103d831>] intel_thermal_interrupt+0x211/0x250
[<ffffffff8103d8c1>] smp_thermal_interrupt+0x21/0x40
[<ffffffff8169415d>] thermal_interrupt+0x6d/0x80

Let's defer the work to a kthread.

Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/thermal/x86_pkg_temp_thermal.c | 49 ++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/x86_pkg_temp_thermal.c b/drivers/thermal/x86_pkg_temp_thermal.c
index 9ea3d9d..001ba02 100644
--- a/drivers/thermal/x86_pkg_temp_thermal.c
+++ b/drivers/thermal/x86_pkg_temp_thermal.c
@@ -29,6 +29,7 @@
 #include <linux/pm.h>
 #include <linux/thermal.h>
 #include <linux/debugfs.h>
+#include <linux/work-simple.h>
 #include <asm/cpu_device_id.h>
 #include <asm/mce.h>
 
@@ -352,7 +353,7 @@ static void pkg_temp_thermal_threshold_work_fn(struct work_struct *work)
 	}
 }
 
-static int pkg_temp_thermal_platform_thermal_notify(__u64 msr_val)
+static void platform_thermal_notify_work(struct swork_event *event)
 {
 	unsigned long flags;
 	int cpu = smp_processor_id();
@@ -369,7 +370,7 @@ static int pkg_temp_thermal_platform_thermal_notify(__u64 msr_val)
 			pkg_work_scheduled[phy_id]) {
 		disable_pkg_thres_interrupt();
 		spin_unlock_irqrestore(&pkg_work_lock, flags);
-		return -EINVAL;
+		return;
 	}
 	pkg_work_scheduled[phy_id] = 1;
 	spin_unlock_irqrestore(&pkg_work_lock, flags);
@@ -378,9 +379,48 @@ static int pkg_temp_thermal_platform_thermal_notify(__u64 msr_val)
 	schedule_delayed_work_on(cpu,
 				&per_cpu(pkg_temp_thermal_threshold_work, cpu),
 				msecs_to_jiffies(notify_delay_ms));
+}
+
+#ifdef CONFIG_PREEMPT_RT_FULL
+static struct swork_event notify_work;
+
+static int thermal_notify_work_init(void)
+{
+	int err;
+
+	err = swork_get();
+	if (!err)
+		return err;
+
+	INIT_SWORK(&notify_work, platform_thermal_notify_work);
+	return 0;
+}
+
+static void thermal_notify_work_cleanup(void)
+{
+	swork_put();
+}
+
+static int pkg_temp_thermal_platform_thermal_notify(__u64 msr_val)
+{
+	swork_queue(&notify_work);
 	return 0;
 }
 
+#else  /* !CONFIG_PREEMPT_RT_FULL */
+
+static int thermal_notify_work_init(void) { return 0; }
+
+static int thermal_notify_work_cleanup(void) {  }
+
+static int pkg_temp_thermal_platform_thermal_notify(__u64 msr_val)
+{
+	platform_thermal_notify_work(NULL);
+
+	return 0;
+}
+#endif /* CONFIG_PREEMPT_RT_FULL */
+
 static int find_siblings_cpu(int cpu)
 {
 	int i;
@@ -594,6 +634,10 @@ static int __init pkg_temp_thermal_init(void)
 	for_each_online_cpu(i)
 		if (get_core_online(i))
 			goto err_ret;
+
+	if (!thermal_notify_work_init())
+		goto err_ret;
+
 	__register_hotcpu_notifier(&pkg_temp_thermal_notifier);
 	cpu_notifier_register_done();
 
@@ -619,6 +663,7 @@ static void __exit pkg_temp_thermal_exit(void)
 
 	cpu_notifier_register_begin();
 	__unregister_hotcpu_notifier(&pkg_temp_thermal_notifier);
+	thermal_notify_work_cleanup();
 	mutex_lock(&phy_dev_list_mutex);
 	list_for_each_entry_safe(phdev, n, &phy_dev_list, list) {
 		/* Retore old MSR value for package thermal interrupt */
-- 
2.1.0