Merge branch 'perf/urgent' into perf/core

Merge in all fixes before applying more changes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/events/core.c

@@ -253,9 +253,9 @@ perf_cgroup_match(struct perf_event *event)
 	return !event->cgrp || event->cgrp == cpuctx->cgrp;
 }
 
-static inline void perf_get_cgroup(struct perf_event *event)
+static inline bool perf_tryget_cgroup(struct perf_event *event)
 {
-	css_get(&event->cgrp->css);
+	return css_tryget(&event->cgrp->css);
 }
 
 static inline void perf_put_cgroup(struct perf_event *event)
@@ -484,7 +484,11 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event,
 	event->cgrp = cgrp;
 
 	/* must be done before we fput() the file */
-	perf_get_cgroup(event);
+	if (!perf_tryget_cgroup(event)) {
+		event->cgrp = NULL;
+		ret = -ENOENT;
+		goto out;
+	}
 
 	/*
 	 * all events in a group must monitor

kernel/trace/trace.c

@@ -371,7 +371,7 @@ EXPORT_SYMBOL_GPL(tracing_on);
 void tracing_off(void)
 {
 	if (global_trace.buffer)
-		ring_buffer_record_on(global_trace.buffer);
+		ring_buffer_record_off(global_trace.buffer);
 	/*
 	 * This flag is only looked at when buffers haven't been
 	 * allocated yet. We don't really care about the race

kernel/watchdog.c

@@ -372,6 +372,13 @@ static int watchdog(void *unused)
 
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
+/*
+ * People like the simple clean cpu node info on boot.
+ * Reduce the watchdog noise by only printing messages
+ * that are different from what cpu0 displayed.
+ */
+static unsigned long cpu0_err;
+
 static int watchdog_nmi_enable(int cpu)
 {
 	struct perf_event_attr *wd_attr;
@@ -390,11 +397,21 @@ 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);
+
+	/* save cpu0 error for future comparision */
+	if (cpu == 0 && IS_ERR(event))
+		cpu0_err = PTR_ERR(event);
+
 	if (!IS_ERR(event)) {
-		pr_info("enabled, takes one hw-pmu counter.\n");
+		/* only print for cpu0 or different than cpu0 */
+		if (cpu == 0 || cpu0_err)
+			pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
 		goto out_save;
 	}
 
+	/* skip displaying the same error again */
+	if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
+		return PTR_ERR(event);
 
 	/* vary the KERN level based on the returned errno */
 	if (PTR_ERR(event) == -EOPNOTSUPP)