Commit-ID: 6592ad2fcc8f15b4f99b36c1db7d9f65510c203b
Gitweb: http://git.kernel.org/tip/6592ad2fcc8f15b4f99b36c1db7d9f65510c203b
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 12 Sep 2017 21:37:16 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 14 Sep 2017 11:41:07 +0200
watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage
Both the perf reconfiguration and the powerpc watchdog_nmi_reconfigure()
need to be done in two steps.
1) Stop all NMIs
2) Read the new parameters and start NMIs
Right now watchdog_nmi_reconfigure() is a combination of both. To allow a
clean reconfiguration add a 'run' argument and split the functionality in
powerpc.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Sebastian Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170912194147.862865570@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/powerpc/kernel/watchdog.c | 17 +++++++++--------
include/linux/nmi.h | 2 ++
kernel/watchdog.c | 31 ++++++++++++++++++++++---------
3 files changed, 33 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index 5ded171..291af79 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -355,17 +355,18 @@ static void watchdog_calc_timeouts(void)
wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5;
}
-void watchdog_nmi_reconfigure(void)
+void watchdog_nmi_reconfigure(bool run)
{
int cpu;
- watchdog_calc_timeouts();
-
- for_each_cpu(cpu, &wd_cpus_enabled)
- stop_wd_on_cpu(cpu);
-
- for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
- start_wd_on_cpu(cpu);
+ if (!run) {
+ for_each_cpu(cpu, &wd_cpus_enabled)
+ stop_wd_on_cpu(cpu);
+ } else {
+ watchdog_calc_timeouts();
+ for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
+ start_wd_on_cpu(cpu);
+ }
}
/*
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 4a8d103..eee255b 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -103,6 +103,8 @@ static inline void arch_touch_nmi_watchdog(void) {}
#endif
#endif
+void watchdog_nmi_reconfigure(bool run);
+
/**
* touch_nmi_watchdog - restart NMI watchdog timeout.
*
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index baae9fc..5693afd 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -112,17 +112,25 @@ void __weak watchdog_nmi_disable(unsigned int cpu)
hardlockup_detector_perf_disable();
}
-/*
- * watchdog_nmi_reconfigure can be implemented to be notified after any
- * watchdog configuration change. The arch hardlockup watchdog should
- * respond to the following variables:
+/**
+ * watchdog_nmi_reconfigure - Optional function to reconfigure NMI watchdogs
+ * @run: If false stop the watchdogs on all enabled CPUs
+ * If true start the watchdogs on all enabled CPUs
+ *
+ * The core call order is:
+ * watchdog_nmi_reconfigure(false);
+ * update_variables();
+ * watchdog_nmi_reconfigure(true);
+ *
+ * The second call which starts the watchdogs again guarantees that the
+ * following variables are stable across the call.
* - watchdog_enabled
* - watchdog_thresh
* - watchdog_cpumask
- * - sysctl_hardlockup_all_cpu_backtrace
- * - hardlockup_panic
+ *
+ * After the call the variables can be changed again.
*/
-void __weak watchdog_nmi_reconfigure(void) { }
+void __weak watchdog_nmi_reconfigure(bool run) { }
#ifdef CONFIG_SOFTLOCKUP_DETECTOR
@@ -515,10 +523,12 @@ static void softlockup_unpark_threads(void)
static void softlockup_reconfigure_threads(bool enabled)
{
+ watchdog_nmi_reconfigure(false);
softlockup_park_all_threads();
set_sample_period();
if (enabled)
softlockup_unpark_threads();
+ watchdog_nmi_reconfigure(true);
}
/*
@@ -559,7 +569,11 @@ static inline void watchdog_unpark_threads(void) { }
static inline int watchdog_enable_all_cpus(void) { return 0; }
static inline void watchdog_disable_all_cpus(void) { }
static inline void softlockup_init_threads(void) { }
-static inline void softlockup_reconfigure_threads(bool enabled) { }
+static void softlockup_reconfigure_threads(bool enabled)
+{
+ watchdog_nmi_reconfigure(false);
+ watchdog_nmi_reconfigure(true);
+}
#endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
static void __lockup_detector_cleanup(void)
@@ -599,7 +613,6 @@ static void proc_watchdog_update(void)
/* Remove impossible cpus to keep sysctl output clean. */
cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
softlockup_reconfigure_threads(watchdog_enabled && watchdog_thresh);
- watchdog_nmi_reconfigure();
}
/*
--
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