aboutsummaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorPeter Zijlstra <peterz@infradead.org>2017-09-20 19:00:21 +0200
committerThomas Gleixner <tglx@linutronix.de>2017-09-25 22:11:44 +0200
commit1db49484f21ed0fcdadd0635a3669f5f386546fa (patch)
tree533d9d2c340550a1b60bafcf77eff90fce1fe409 /kernel
parent5ebe7742fff8be5f1359bc50f5d43fb6ff7bd060 (diff)
download96b-common-1db49484f21ed0fcdadd0635a3669f5f386546fa.tar.gz
smp/hotplug: Hotplug state fail injection
Add a sysfs file to one-time fail a specific state. This can be used to test the state rollback code paths. Something like this (hotplug-up.sh): #!/bin/bash echo 0 > /debug/sched_debug echo 1 > /debug/tracing/events/cpuhp/enable ALL_STATES=`cat /sys/devices/system/cpu/hotplug/states | cut -d':' -f1` STATES=${1:-$ALL_STATES} for state in $STATES do echo 0 > /sys/devices/system/cpu/cpu1/online echo 0 > /debug/tracing/trace echo Fail state: $state echo $state > /sys/devices/system/cpu/cpu1/hotplug/fail cat /sys/devices/system/cpu/cpu1/hotplug/fail echo 1 > /sys/devices/system/cpu/cpu1/online cat /debug/tracing/trace > hotfail-${state}.trace sleep 1 done Can be used to test for all possible rollback (barring multi-instance) scenarios on CPU-up, CPU-down is a trivial modification of the above. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: bigeasy@linutronix.de Cc: efault@gmx.de Cc: rostedt@goodmis.org Cc: max.byungchul.park@gmail.com Link: https://lkml.kernel.org/r/20170920170546.972581715@infradead.org
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpu.c60
1 files changed, 59 insertions, 1 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6bbe261b851f..8de11a29e495 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -52,6 +52,7 @@
struct cpuhp_cpu_state {
enum cpuhp_state state;
enum cpuhp_state target;
+ enum cpuhp_state fail;
#ifdef CONFIG_SMP
struct task_struct *thread;
bool should_run;
@@ -67,7 +68,9 @@ struct cpuhp_cpu_state {
#endif
};
-static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
+static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
+ .fail = CPUHP_INVALID,
+};
#if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP)
static struct lockdep_map cpuhp_state_up_map =
@@ -160,6 +163,15 @@ static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
int (*cb)(unsigned int cpu);
int ret, cnt;
+ if (st->fail == state) {
+ st->fail = CPUHP_INVALID;
+
+ if (!(bringup ? step->startup.single : step->teardown.single))
+ return 0;
+
+ return -EAGAIN;
+ }
+
if (!step->multi_instance) {
WARN_ON_ONCE(lastp && *lastp);
cb = bringup ? step->startup.single : step->teardown.single;
@@ -1805,9 +1817,55 @@ static ssize_t show_cpuhp_target(struct device *dev,
}
static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);
+
+static ssize_t write_cpuhp_fail(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+ struct cpuhp_step *sp;
+ int fail, ret;
+
+ ret = kstrtoint(buf, 10, &fail);
+ if (ret)
+ return ret;
+
+ /*
+ * Cannot fail STARTING/DYING callbacks.
+ */
+ if (cpuhp_is_atomic_state(fail))
+ return -EINVAL;
+
+ /*
+ * Cannot fail anything that doesn't have callbacks.
+ */
+ mutex_lock(&cpuhp_state_mutex);
+ sp = cpuhp_get_step(fail);
+ if (!sp->startup.single && !sp->teardown.single)
+ ret = -EINVAL;
+ mutex_unlock(&cpuhp_state_mutex);
+ if (ret)
+ return ret;
+
+ st->fail = fail;
+
+ return count;
+}
+
+static ssize_t show_cpuhp_fail(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
+
+ return sprintf(buf, "%d\n", st->fail);
+}
+
+static DEVICE_ATTR(fail, 0644, show_cpuhp_fail, write_cpuhp_fail);
+
static struct attribute *cpuhp_cpu_attrs[] = {
&dev_attr_state.attr,
&dev_attr_target.attr,
+ &dev_attr_fail.attr,
NULL
};