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authorThomas Gleixner <tglx@linutronix.de>2017-09-12 21:37:00 +0200
committerIngo Molnar <mingo@kernel.org>2017-09-14 11:41:04 +0200
commitb7a349819d4b9b5db64e523351e66a79a758eaa5 (patch)
tree92f64ad56f0be008103710de0f8911fc8548820b /kernel/watchdog.c
parent5490125d77a43016b26f629d4b485e2c62172551 (diff)
downloadlinux-b7a349819d4b9b5db64e523351e66a79a758eaa5.tar.bz2
watchdog/core: Rework CPU hotplug locking
The watchdog proc interface causes extensive recursive locking of the CPU hotplug percpu rwsem, which is deadlock prone. Replace the get/put_online_cpus() pairs with cpu_hotplug_disable()/enable() calls for now. Later patches will remove that requirement completely. Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194146.568079057@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/watchdog.c')
-rw-r--r--kernel/watchdog.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index b2d46757917e..cd79f644ea34 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -703,7 +703,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
int err, old, new;
int *watchdog_param = (int *)table->data;
- get_online_cpus();
+ cpu_hotplug_disable();
mutex_lock(&watchdog_proc_mutex);
/*
@@ -752,7 +752,7 @@ static int proc_watchdog_common(int which, struct ctl_table *table, int write,
}
out:
mutex_unlock(&watchdog_proc_mutex);
- put_online_cpus();
+ cpu_hotplug_enable();
return err;
}
@@ -794,7 +794,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
{
int err, old, new;
- get_online_cpus();
+ cpu_hotplug_disable();
mutex_lock(&watchdog_proc_mutex);
old = ACCESS_ONCE(watchdog_thresh);
@@ -818,7 +818,7 @@ int proc_watchdog_thresh(struct ctl_table *table, int write,
}
out:
mutex_unlock(&watchdog_proc_mutex);
- put_online_cpus();
+ cpu_hotplug_enable();
return err;
}
@@ -833,7 +833,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
{
int err;
- get_online_cpus();
+ cpu_hotplug_disable();
mutex_lock(&watchdog_proc_mutex);
err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
@@ -856,7 +856,7 @@ int proc_watchdog_cpumask(struct ctl_table *table, int write,
}
mutex_unlock(&watchdog_proc_mutex);
- put_online_cpus();
+ cpu_hotplug_enable();
return err;
}