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-rw-r--r--kernel/trace/trace.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 551a7cd0d705..0f47e653ffd8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -41,6 +41,7 @@
#include <linux/nmi.h>
#include <linux/fs.h>
#include <linux/trace.h>
+#include <linux/sched/clock.h>
#include <linux/sched/rt.h>
#include "trace.h"
@@ -8596,3 +8597,21 @@ __init static int clear_boot_tracer(void)
fs_initcall(tracer_init_tracefs);
late_initcall_sync(clear_boot_tracer);
+
+#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+__init static int tracing_set_default_clock(void)
+{
+ /* sched_clock_stable() is determined in late_initcall */
+ if (trace_boot_clock || sched_clock_stable()) {
+ printk(KERN_WARNING
+ "Unstable clock detected, switching default tracing clock to \"global\"\n"
+ "If you want to keep using the local clock, then add:\n"
+ " \"trace_clock=local\"\n"
+ "on the kernel command line\n");
+ tracing_set_clock(&global_trace, "global");
+ }
+
+ return 0;
+}
+late_initcall_sync(tracing_set_default_clock);
+#endif