[PATCH -stable 4.1 3/4] perf/core: Make sysctl_perf_cpu_time_max_percent conform to documentation

[Tan Xiaojun <tanxiaojun@huawei.com>]

From: Peter Zijlstra <peterz@infradead.org>

Markus reported that 0 should also disable the throttling we per
Documentation/sysctl/kernel.txt.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 91a612eea9a3 ("perf/core: Fix dynamic interrupt throttle")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Tan Xiaojun <tanxiaojun@huawei.com>
---
 kernel/events/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f96ad76..350c45a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -241,7 +241,8 @@ int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 	if (ret || !write)
 		return ret;
 
-	if (sysctl_perf_cpu_time_max_percent == 100) {
+	if (sysctl_perf_cpu_time_max_percent == 100 ||
+	    sysctl_perf_cpu_time_max_percent == 0) {
 		printk(KERN_WARNING
 		       "perf: Dynamic interrupt throttling disabled, can hang your system!\n");
 		WRITE_ONCE(perf_sample_allowed_ns, 0);
-- 
1.9.1