[PATCH v2] watchdog: Reduce message verbosity

[PATCH v2] watchdog: Reduce message verbosity

[Sinan Kaya]

Code is emitting the following error message during boot on systems
without PMU hardware support while probing NMI capability.

NMI watchdog: Perf event create on CPU 0 failed with -2

This error is coming from this path:

lockup_detector_init
  watchdog_nmi_probe
    hardlockup_detector_perf_init
      hardlockup_detector_event_create
        perf_event_create_kernel_counter
          perf_event_alloc
            perf_init_event (9539)
              pmu = ERR_PTR(-ENOENT) due to lack of PMUs in the system

followed by the warning that NMI watchdog is disabled as follows.

NMI watchdog: Perf NMI watchdog permanently disabled

While NMI disabled information is usefel for ordinary users, seeing
a PERF event create failed with error code -2 is too verbose.

Reducing the message severity to debug so that if somebody is really
wants to debug this, they can find out the error source by increasing
the kernel loglevel during boot.

Signed-off-by: Sinan Kaya <okaya@kernel.org>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=599368
---
 kernel/watchdog_hld.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index e449a23e9d59..1f7020d65d0a 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -175,8 +175,8 @@ static int hardlockup_detector_event_create(void)
 	evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
 					       watchdog_overflow_callback, NULL);
 	if (IS_ERR(evt)) {
-		pr_info("Perf event create on CPU %d failed with %ld\n", cpu,
-			PTR_ERR(evt));
+		pr_debug("Perf event create on CPU %d failed with %ld\n", cpu,
+			 PTR_ERR(evt));
 		return PTR_ERR(evt);
 	}
 	this_cpu_write(watchdog_ev, evt);
-- 
2.17.1

[tip:sched/core] watchdog: Reduce message verbosity

[tip-bot for Sinan Kaya]

Commit-ID:  1b6266ebe3da8198e9a02fbad77bbb56e2f7ce2e
Gitweb:     https://git.kernel.org/tip/1b6266ebe3da8198e9a02fbad77bbb56e2f7ce2e
Author:     Sinan Kaya <okaya@kernel.org>
AuthorDate: Thu, 2 Aug 2018 23:09:41 -0700
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 3 Aug 2018 12:19:08 +0200

watchdog: Reduce message verbosity

Code is emitting the following error message during boot on systems
without PMU hardware support while probing NMI capability.

 NMI watchdog: Perf event create on CPU 0 failed with -2

This error is emitted as the perf subsystem returns -ENOENT due to lack of
PMUs in the system.

It is followed by the warning that NMI watchdog is disabled:

  NMI watchdog: Perf NMI watchdog permanently disabled

While NMI disabled information is useful for ordinary users, seeing a PERF
event create failed with error code -2 is not.

Reduce the message severity to debug so that if debugging is still possible
in case the error code returned by perf is required for analysis.

Signed-off-by: Sinan Kaya <okaya@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=599368
Link: https://lkml.kernel.org/r/20180803060943.2643-1-okaya@kernel.org

---
 kernel/watchdog_hld.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index e449a23e9d59..1f7020d65d0a 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -175,8 +175,8 @@ static int hardlockup_detector_event_create(void)
 	evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
 					       watchdog_overflow_callback, NULL);
 	if (IS_ERR(evt)) {
-		pr_info("Perf event create on CPU %d failed with %ld\n", cpu,
-			PTR_ERR(evt));
+		pr_debug("Perf event create on CPU %d failed with %ld\n", cpu,
+			 PTR_ERR(evt));
 		return PTR_ERR(evt);
 	}
 	this_cpu_write(watchdog_ev, evt);