patches/x86-mce-timer-hrtimer.patch

From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 13 Dec 2010 16:33:39 +0100
Subject: x86: Convert mce timer to hrtimer

mce_timer is started in atomic contexts of cpu bringup. This results
in might_sleep() warnings on RT. Convert mce_timer to a hrtimer to
avoid this.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 arch/x86/kernel/cpu/mcheck/mce.c |   57 ++++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 24 deletions(-)

--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -41,6 +41,7 @@
 #include <linux/debugfs.h>
 #include <linux/irq_work.h>
 #include <linux/export.h>
+#include <linux/jiffies.h>
 
 #include <asm/processor.h>
 #include <asm/mce.h>
@@ -1259,7 +1260,7 @@ void mce_log_therm_throt_event(__u64 sta
 static unsigned long check_interval = 5 * 60; /* 5 minutes */
 
 static DEFINE_PER_CPU(unsigned long, mce_next_interval); /* in jiffies */
-static DEFINE_PER_CPU(struct timer_list, mce_timer);
+static DEFINE_PER_CPU(struct hrtimer, mce_timer);
 
 static unsigned long mce_adjust_timer_default(unsigned long interval)
 {
@@ -1269,13 +1270,10 @@ static unsigned long mce_adjust_timer_de
 static unsigned long (*mce_adjust_timer)(unsigned long interval) =
 	mce_adjust_timer_default;
 
-static void mce_timer_fn(unsigned long data)
+static enum hrtimer_restart mce_timer_fn(struct hrtimer *timer)
 {
-	struct timer_list *t = &__get_cpu_var(mce_timer);
 	unsigned long iv;
 
-	WARN_ON(smp_processor_id() != data);
-
 	if (mce_available(__this_cpu_ptr(&cpu_info))) {
 		machine_check_poll(MCP_TIMESTAMP,
 				&__get_cpu_var(mce_poll_banks));
@@ -1296,9 +1294,10 @@ static void mce_timer_fn(unsigned long d
 	__this_cpu_write(mce_next_interval, iv);
 	/* Might have become 0 after CMCI storm subsided */
 	if (iv) {
-		t->expires = jiffies + iv;
-		add_timer_on(t, smp_processor_id());
+		hrtimer_forward_now(timer, ns_to_ktime(jiffies_to_usecs(iv)));
+		return HRTIMER_RESTART;
 	}
+	return HRTIMER_NORESTART;
 }
 
 /*
@@ -1306,28 +1305,37 @@ static void mce_timer_fn(unsigned long d
  */
 void mce_timer_kick(unsigned long interval)
 {
-	struct timer_list *t = &__get_cpu_var(mce_timer);
-	unsigned long when = jiffies + interval;
+	struct hrtimer *t = &__get_cpu_var(mce_timer);
 	unsigned long iv = __this_cpu_read(mce_next_interval);
 
-	if (timer_pending(t)) {
-		if (time_before(when, t->expires))
-			mod_timer_pinned(t, when);
+	if (hrtimer_active(t)) {
+		s64 exp;
+		s64 intv_us;
+
+		intv_us = jiffies_to_usecs(interval);
+		exp = ktime_to_us(hrtimer_expires_remaining(t));
+		if (intv_us < exp) {
+			hrtimer_cancel(t);
+			hrtimer_start_range_ns(t,
+					ns_to_ktime(intv_us * 1000),
+					0, HRTIMER_MODE_REL_PINNED);
+		}
 	} else {
-		t->expires = round_jiffies(when);
-		add_timer_on(t, smp_processor_id());
+		hrtimer_start_range_ns(t,
+				ns_to_ktime(jiffies_to_usecs(interval) * 1000),
+				0, HRTIMER_MODE_REL_PINNED);
 	}
 	if (interval < iv)
 		__this_cpu_write(mce_next_interval, interval);
 }
 
-/* Must not be called in IRQ context where del_timer_sync() can deadlock */
+/* Must not be called in IRQ context where hrtimer_cancel() can deadlock */
 static void mce_timer_delete_all(void)
 {
 	int cpu;
 
 	for_each_online_cpu(cpu)
-		del_timer_sync(&per_cpu(mce_timer, cpu));
+		hrtimer_cancel(&per_cpu(mce_timer, cpu));
 }
 
 static void mce_do_trigger(struct work_struct *work)
@@ -1632,7 +1640,7 @@ static void __mcheck_cpu_init_vendor(str
 	}
 }
 
-static void mce_start_timer(unsigned int cpu, struct timer_list *t)
+static void mce_start_timer(unsigned int cpu, struct hrtimer *t)
 {
 	unsigned long iv = mce_adjust_timer(check_interval * HZ);
 
@@ -1641,16 +1649,17 @@ static void mce_start_timer(unsigned int
 	if (mca_cfg.ignore_ce || !iv)
 		return;
 
-	t->expires = round_jiffies(jiffies + iv);
-	add_timer_on(t, smp_processor_id());
+	hrtimer_start_range_ns(t, ns_to_ktime(jiffies_to_usecs(iv) * 1000),
+			0, HRTIMER_MODE_REL_PINNED);
 }
 
 static void __mcheck_cpu_init_timer(void)
 {
-	struct timer_list *t = &__get_cpu_var(mce_timer);
+	struct hrtimer *t = &__get_cpu_var(mce_timer);
 	unsigned int cpu = smp_processor_id();
 
-	setup_timer(t, mce_timer_fn, cpu);
+	hrtimer_init(t, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	t->function = mce_timer_fn;
 	mce_start_timer(cpu, t);
 }
 
@@ -2307,6 +2316,8 @@ static void __cpuinit mce_disable_cpu(vo
 	if (!mce_available(__this_cpu_ptr(&cpu_info)))
 		return;
 
+	hrtimer_cancel(&__get_cpu_var(mce_timer));
+
 	if (!(action & CPU_TASKS_FROZEN))
 		cmci_clear();
 	for (i = 0; i < mca_cfg.banks; i++) {
@@ -2333,6 +2344,7 @@ static void __cpuinit mce_reenable_cpu(v
 		if (b->init)
 			wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl);
 	}
+	__mcheck_cpu_init_timer();
 }
 
 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
@@ -2340,7 +2352,6 @@ static int __cpuinit
 mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
-	struct timer_list *t = &per_cpu(mce_timer, cpu);
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_ONLINE:
@@ -2356,11 +2367,9 @@ mce_cpu_callback(struct notifier_block *
 		break;
 	case CPU_DOWN_PREPARE:
 		smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
-		del_timer_sync(t);
 		break;
 	case CPU_DOWN_FAILED:
 		smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
-		mce_start_timer(cpu, t);
 		break;
 	}