Architecture code can ask file system code to enable events. But there
is no way to clean up and disable events.

Add resctrl_disable_mon_event(). Adding/removing events is only
possible when the file system is not mounted. Add a WARN_ON() to
catch misuse.

Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 include/linux/resctrl.h |  1 +
 fs/resctrl/monitor.c    | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 006e57fd7ca5..b312aaf76974 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -416,6 +416,7 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
 bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
 			      unsigned int binary_bits, void *arch_priv);
+void resctrl_disable_mon_event(enum resctrl_event_id eventid);
 
 bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
 
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 49f3f6b846b2..50eb5534767c 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -990,6 +990,8 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] = {
 bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
 			      unsigned int binary_bits, void *arch_priv)
 {
+	if (WARN_ON(resctrl_mounted))
+		return false;
 	if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >= QOS_NUM_EVENTS ||
 			 binary_bits > MAX_BINARY_BITS))
 		return false;
@@ -1010,6 +1012,20 @@ bool resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,
 	return true;
 }
 
+void resctrl_disable_mon_event(enum resctrl_event_id eventid)
+{
+	if (WARN_ON(resctrl_mounted))
+		return;
+	if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >= QOS_NUM_EVENTS))
+		return;
+	if (!mon_event_all[eventid].enabled) {
+		pr_warn("Repeat disable for event %d\n", eventid);
+		return;
+	}
+
+	mon_event_all[eventid].enabled = false;
+}
+
 bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid)
 {
 	return eventid >= QOS_FIRST_EVENT && eventid < QOS_NUM_EVENTS &&
-- 
2.53.0