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watchdog/hardlockup: Clean up hotplug locking mess 

All watchdog thread related functions are delegated to the smpboot thread
infrastructure, which handles serialization against CPU hotplug correctly.

The sysctl interface is completely decoupled from anything which requires
CPU hotplug protection.

No need to protect the sysctl writes against cpu hotplug anymore. Remove it
and add the now required protection to the powerpc arch_nmi_watchdog
implementation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Don Zickus <dzickus@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20170912194148.418497420@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Thomas Gleixner 2017-09-12 21:37:23 +02:00 committed by Ingo Molnar
parent a33d44843d
commit ab5fe3ff38
2 changed files with 2 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/kernel/watchdog.c
View File

@ -359,6 +359,7 @@ void watchdog_nmi_reconfigure(bool run)
{
int cpu;
cpus_read_lock();
if (!run) {
for_each_cpu(cpu, &wd_cpus_enabled)
stop_wd_on_cpu(cpu);
@ -367,6 +368,7 @@ void watchdog_nmi_reconfigure(bool run)
for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
start_wd_on_cpu(cpu);
}
cpus_read_unlock();
}
/*

6
kernel/watchdog.c
View File

@ -664,7 +664,6 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
{
int err, old, *param = table->data;
cpu_hotplug_disable();
mutex_lock(&watchdog_mutex);
if (!write) {
@ -681,7 +680,6 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
proc_watchdog_update();
}
mutex_unlock(&watchdog_mutex);
cpu_hotplug_enable();
return err;
}
@ -725,7 +723,6 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
{
int err, old;
cpu_hotplug_disable();
mutex_lock(&watchdog_mutex);
old = READ_ONCE(watchdog_thresh);
@ -735,7 +732,6 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
proc_watchdog_update();
mutex_unlock(&watchdog_mutex);
cpu_hotplug_enable();
return err;
}
@ -750,7 +746,6 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
{
int err;
cpu_hotplug_disable();
mutex_lock(&watchdog_mutex);
err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
@ -758,7 +753,6 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
proc_watchdog_update();
mutex_unlock(&watchdog_mutex);
cpu_hotplug_enable();
return err;
}
#endif /* CONFIG_SYSCTL */