[PATCH 10/10] rcu: Nocb (de)activate through sysfs

Frederic Weisbecker
2020-05-13T16:47:42Z

Not for merge.

Make nocb toggable for a given CPU using:
/sys/devices/system/cpu/cpu*/hotplug/nocb

This is only intended for those who want to test this patchset. The real
interfaces will be cpuset/isolation and rcutorture.

Not-Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
---
kernel/cpu.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 2371292f30b0..ac6283dcb897 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2208,10 +2208,33 @@ static ssize_t show_cpuhp_fail(struct device *dev,

static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail);

+static ssize_t write_nocb(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int val, ret;
+
+ ret = kstrtoint(buf, 10, &val);
+ if (ret)
+ return ret;
+
+ if (val == 0)
+ rcu_nocb_cpu_deoffload(dev->id);
+ else if (val == 1)
+ rcu_nocb_cpu_offload(dev->id);
+ else
+ return -EINVAL;
+
+ return count;
+}
+
+static DEVICE_ATTR(nocb, 0644, NULL, write_nocb);
+
static struct attribute *cpuhp_cpu_attrs[] = {
&dev_attr_state.attr,
&dev_attr_target.attr,
&dev_attr_fail.attr,
+ &dev_attr_nocb.attr,
NULL
};

--
2.25.0