[PATCH net-next v3 2/5] netconsole: implement configfs for msgid_enabled

[Gustavo Luiz Duarte <gustavold@xxxxxxxxx>]

Implement the _show and _store functions for the msgid_enabled configfs
attribute under userdata.
Set the sysdata_fields bit accordingly.

Reviewed-by: Breno Leitao <leitao@xxxxxxxxxx>
Signed-off-by: Gustavo Luiz Duarte <gustavold@xxxxxxxxx>
---
 drivers/net/netconsole.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 5f8c8c6c5393..3bf8777fcd01 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -489,6 +489,19 @@ static void unregister_netcons_consoles(void)
 		unregister_console(&netconsole);
 }
 
+static ssize_t sysdata_msgid_enabled_show(struct config_item *item,
+					  char *buf)
+{
+	struct netconsole_target *nt = to_target(item->ci_parent);
+	bool msgid_enabled;
+
+	mutex_lock(&dynamic_netconsole_mutex);
+	msgid_enabled = !!(nt->sysdata_fields & SYSDATA_MSGID);
+	mutex_unlock(&dynamic_netconsole_mutex);
+
+	return sysfs_emit(buf, "%d\n", msgid_enabled);
+}
+
 /*
  * This one is special -- targets created through the configfs interface
  * are not enabled (and the corresponding netpoll activated) by default.
@@ -922,6 +935,40 @@ static void disable_sysdata_feature(struct netconsole_target *nt,
 	nt->extradata_complete[nt->userdata_length] = 0;
 }
 
+static ssize_t sysdata_msgid_enabled_store(struct config_item *item,
+					   const char *buf, size_t count)
+{
+	struct netconsole_target *nt = to_target(item->ci_parent);
+	bool msgid_enabled, curr;
+	ssize_t ret;
+
+	ret = kstrtobool(buf, &msgid_enabled);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dynamic_netconsole_mutex);
+	curr = !!(nt->sysdata_fields & SYSDATA_MSGID);
+	if (msgid_enabled == curr)
+		goto unlock_ok;
+
+	if (msgid_enabled &&
+	    count_extradata_entries(nt) >= MAX_EXTRADATA_ITEMS) {
+		ret = -ENOSPC;
+		goto unlock;
+	}
+
+	if (msgid_enabled)
+		nt->sysdata_fields |= SYSDATA_MSGID;
+	else
+		disable_sysdata_feature(nt, SYSDATA_MSGID);
+
+unlock_ok:
+	ret = strnlen(buf, count);
+unlock:
+	mutex_unlock(&dynamic_netconsole_mutex);
+	return ret;
+}
+
 static ssize_t sysdata_release_enabled_store(struct config_item *item,
 					     const char *buf, size_t count)
 {
@@ -1037,6 +1084,7 @@ CONFIGFS_ATTR(userdatum_, value);
 CONFIGFS_ATTR(sysdata_, cpu_nr_enabled);
 CONFIGFS_ATTR(sysdata_, taskname_enabled);
 CONFIGFS_ATTR(sysdata_, release_enabled);
+CONFIGFS_ATTR(sysdata_, msgid_enabled);
 
 static struct configfs_attribute *userdatum_attrs[] = {
 	&userdatum_attr_value,
@@ -1099,6 +1147,7 @@ static struct configfs_attribute *userdata_attrs[] = {
 	&sysdata_attr_cpu_nr_enabled,
 	&sysdata_attr_taskname_enabled,
 	&sysdata_attr_release_enabled,
+	&sysdata_attr_msgid_enabled,
 	NULL,
 };
 

-- 
2.47.1