1 files changed, 17 insertions, 10 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 14bc092fb12c..df30ee08bdd4 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -9,6 +9,8 @@
  * to those contributors as well.
  */
 
+#define pr_fmt(fmt) "NMI watchdog: " fmt
+
 #include <linux/mm.h>
 #include <linux/cpu.h>
 #include <linux/nmi.h>
@@ -319,11 +321,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
  */
 static int watchdog(void *unused)
 {
-        struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
+        struct sched_param param = { .sched_priority = 0 };
         struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
 
-        sched_setscheduler(current, SCHED_FIFO, &param);
-
         /* initialize timestamp */
         __touch_watchdog();
 
@@ -349,8 +349,11 @@ static int watchdog(void *unused)
 
                 set_current_state(TASK_INTERRUPTIBLE);
         }
+        /*
+         * Drop the policy/priority elevation during thread exit to avoid a
+         * scheduling latency spike.
+         */
         __set_current_state(TASK_RUNNING);
-        param.sched_priority = 0;
         sched_setscheduler(current, SCHED_NORMAL, &param);
         return 0;
 }
@@ -376,18 +379,20 @@ static int watchdog_nmi_enable(int cpu)
         /* Try to register using hardware perf events */
         event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
         if (!IS_ERR(event)) {
-                printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
+                pr_info("enabled, takes one hw-pmu counter.\n");
                 goto out_save;
         }
 
 
         /* vary the KERN level based on the returned errno */
         if (PTR_ERR(event) == -EOPNOTSUPP)
-                printk(KERN_INFO "NMI watchdog disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
+                pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu);
         else if (PTR_ERR(event) == -ENOENT)
-                printk(KERN_WARNING "NMI watchdog disabled (cpu%i): hardware events not enabled\n", cpu);
+                pr_warning("disabled (cpu%i): hardware events not enabled\n",
+                         cpu);
         else
-                printk(KERN_ERR "NMI watchdog disabled (cpu%i): unable to create perf event: %ld\n", cpu, PTR_ERR(event));
+                pr_err("disabled (cpu%i): unable to create perf event: %ld\n",
+                        cpu, PTR_ERR(event));
         return PTR_ERR(event);
 
         /* success path */
@@ -439,9 +444,10 @@ static int watchdog_enable(int cpu)
 
         /* create the watchdog thread */
         if (!p) {
+                struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
                 p = kthread_create_on_node(watchdog, NULL, cpu_to_node(cpu), "watchdog/%d", cpu);
                 if (IS_ERR(p)) {
-                        printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
+                        pr_err("softlockup watchdog for %i failed\n", cpu);
                         if (!err) {
                                 /* if hardlockup hasn't already set this */
                                 err = PTR_ERR(p);
@@ -450,6 +456,7 @@ static int watchdog_enable(int cpu)
                         }
                         goto out;
                 }
+                sched_setscheduler(p, SCHED_FIFO, &param);
                 kthread_bind(p, cpu);
                 per_cpu(watchdog_touch_ts, cpu) = 0;
                 per_cpu(softlockup_watchdog, cpu) = p;
@@ -496,7 +503,7 @@ static void watchdog_enable_all_cpus(void)
                         watchdog_enabled = 1;
 
         if (!watchdog_enabled)
-                printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
+                pr_err("failed to be enabled on some cpus\n");
 
 }