[tip:core/urgent] watchdog/hardlockup/perf: Implement CPU enable replacement

[tip-bot for Thomas Gleixner]

Commit-ID:  2a1b8ee4f5665b4291e43e4a25d964c3eb2f4c32
Gitweb:     http://git.kernel.org/tip/2a1b8ee4f5665b4291e43e4a25d964c3eb2f4c32
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 12 Sep 2017 21:37:20 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 14 Sep 2017 11:41:08 +0200

watchdog/hardlockup/perf: Implement CPU enable replacement

watchdog_nmi_enable() is an unparseable mess, Provide a clean perf specific
implementation, which will be used when the existing setup/teardown mess is
replaced.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170912194148.180215498@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/linux/nmi.h   |  2 ++
 kernel/watchdog_hld.c | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 72c62a8..89ba8b2 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -92,12 +92,14 @@ extern void arch_touch_nmi_watchdog(void);
 extern void hardlockup_detector_perf_stop(void);
 extern void hardlockup_detector_perf_restart(void);
 extern void hardlockup_detector_perf_disable(void);
+extern void hardlockup_detector_perf_enable(void);
 extern void hardlockup_detector_perf_cleanup(void);
 extern int hardlockup_detector_perf_init(void);
 #else
 static inline void hardlockup_detector_perf_stop(void) { }
 static inline void hardlockup_detector_perf_restart(void) { }
 static inline void hardlockup_detector_perf_disable(void) { }
+static inline void hardlockup_detector_perf_enable(void) { }
 static inline void hardlockup_detector_perf_cleanup(void) { }
 # if !defined(CONFIG_HAVE_NMI_WATCHDOG)
 static inline int hardlockup_detector_perf_init(void) { return -ENODEV; }
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index f7e752e..99a3f22 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -260,6 +260,17 @@ static int hardlockup_detector_event_create(void)
 }
 
 /**
+ * hardlockup_detector_perf_enable - Enable the local event
+ */
+void hardlockup_detector_perf_enable(void)
+{
+	if (hardlockup_detector_event_create())
+		return;
+
+	perf_event_enable(this_cpu_read(watchdog_ev));
+}
+
+/**
  * hardlockup_detector_perf_disable - Disable the local event
  */
 void hardlockup_detector_perf_disable(void)