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Subject[tip:core/watchdog] watchdog/core, powerpc: Replace watchdog_nmi_reconfigure()
Commit-ID:  6b9dc4806b28214a4a260517e59439e0ac12a15e
Gitweb: https://git.kernel.org/tip/6b9dc4806b28214a4a260517e59439e0ac12a15e
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 2 Oct 2017 12:34:50 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 4 Oct 2017 10:53:53 +0200

watchdog/core, powerpc: Replace watchdog_nmi_reconfigure()

The recent cleanup of the watchdog code split watchdog_nmi_reconfigure()
into two stages. One to stop the NMI and one to restart it after
reconfiguration. That was done by adding a boolean 'run' argument to the
code, which is functionally correct but not necessarily a piece of art.

Replace it by two explicit functions: watchdog_nmi_stop() and
watchdog_nmi_start().

Fixes: 6592ad2fcc8f ("watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage")
Requested-by: Linus 'Nursing his pet-peeve' Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Thomas 'Mopping up garbage' Gleixner <tglx@linutronix.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710021957480.2114@nanos

---
arch/powerpc/kernel/watchdog.c | 23 ++++++++++++++---------
include/linux/nmi.h | 3 ++-
kernel/watchdog.c | 33 ++++++++++++++++++---------------
3 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index dfb0677..2673ec8 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -355,19 +355,24 @@ static void watchdog_calc_timeouts(void)
wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5;
}

-void watchdog_nmi_reconfigure(bool run)
+void watchdog_nmi_stop(void)
{
int cpu;

cpus_read_lock();
- 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);
- }
+ for_each_cpu(cpu, &wd_cpus_enabled)
+ stop_wd_on_cpu(cpu);
+ cpus_read_unlock();
+}
+
+void watchdog_nmi_start(void)
+{
+ int cpu;
+
+ cpus_read_lock();
+ watchdog_calc_timeouts();
+ for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
+ start_wd_on_cpu(cpu);
cpus_read_unlock();
}

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 89ba8b2..0c9ed49 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -109,7 +109,8 @@ static inline int hardlockup_detector_perf_init(void) { return 0; }
# endif
#endif

-void watchdog_nmi_reconfigure(bool run);
+void watchdog_nmi_stop(void);
+void watchdog_nmi_start(void);

/**
* touch_nmi_watchdog - restart NMI watchdog timeout.
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index f6ef163..6ad6226 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -123,24 +123,27 @@ int __weak __init watchdog_nmi_probe(void)
}

/**
- * 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
+ * watchdog_nmi_stop - Stop the watchdog for reconfiguration
*
- * The core call order is:
- * watchdog_nmi_reconfigure(false);
+ * The reconfiguration steps are:
+ * watchdog_nmi_stop();
* update_variables();
- * watchdog_nmi_reconfigure(true);
+ * watchdog_nmi_start();
+ */
+void __weak watchdog_nmi_stop(void) { }
+
+/**
+ * watchdog_nmi_start - Start the watchdog after reconfiguration
*
- * The second call which starts the watchdogs again guarantees that the
- * following variables are stable across the call.
+ * Counterpart to watchdog_nmi_stop().
+ *
+ * The following variables have been updated in update_variables() and
+ * contain the currently valid configuration:
* - watchdog_enabled
* - watchdog_thresh
* - watchdog_cpumask
- *
- * After the call the variables can be changed again.
*/
-void __weak watchdog_nmi_reconfigure(bool run) { }
+void __weak watchdog_nmi_start(void) { }

/**
* lockup_detector_update_enable - Update the sysctl enable bit
@@ -551,13 +554,13 @@ static void softlockup_unpark_threads(void)

static void softlockup_reconfigure_threads(void)
{
- watchdog_nmi_reconfigure(false);
+ watchdog_nmi_stop();
softlockup_park_all_threads();
set_sample_period();
lockup_detector_update_enable();
if (watchdog_enabled && watchdog_thresh)
softlockup_unpark_threads();
- watchdog_nmi_reconfigure(true);
+ watchdog_nmi_start();
}

/*
@@ -602,9 +605,9 @@ static inline void watchdog_disable_all_cpus(void) { }
static inline void softlockup_init_threads(void) { }
static void softlockup_reconfigure_threads(void)
{
- watchdog_nmi_reconfigure(false);
+ watchdog_nmi_stop();
lockup_detector_update_enable();
- watchdog_nmi_reconfigure(true);
+ watchdog_nmi_start();
}
#endif /* !CONFIG_SOFTLOCKUP_DETECTOR */

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