[PATCH 1/3] ipmi: msghandler: Get the number of user through sysfs

[Chen Guanqiao <chen.chenchacha@foxmail.com>]

The administrator reads the user_count file corresponding the ipmi device, ipmi
traverse all intf, and count the number of user.

Signed-off-by: Chen Guanqiao <chen.chenchacha@foxmail.com>
---
 drivers/char/ipmi/ipmi_msghandler.c | 33 +++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index c59265146e9c..e14beb51cae4 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -2706,6 +2706,29 @@ static int bmc_get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc,
 	return __bmc_get_device_id(intf, bmc, id, guid_set, guid, -1);
 }
 
+static unsigned int get_user_count(void)
+{
+	struct ipmi_smi *intf;
+	int index;
+	unsigned int total_count = 0;
+
+	index = srcu_read_lock(&ipmi_interfaces_srcu);
+	list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+		struct ipmi_user *user;
+		int intf_index, count = 0;
+
+		intf_index = srcu_read_lock(&intf->users_srcu);
+		list_for_each_entry_rcu(user, &intf->users, link)
+			count++;
+		srcu_read_unlock(&intf->users_srcu, intf_index);
+
+		total_count += count;
+	}
+	srcu_read_unlock(&ipmi_interfaces_srcu, index);
+
+	return total_count;
+}
+
 static ssize_t device_id_show(struct device *dev,
 			      struct device_attribute *attr,
 			      char *buf)
@@ -2875,6 +2898,15 @@ static ssize_t guid_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(guid);
 
+static ssize_t user_count_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	unsigned int user_count = get_user_count();
+
+	return snprintf(buf, 20, "%u\n", user_count);
+}
+static DEVICE_ATTR_ADMIN_RO(user_count);
+
 static struct attribute *bmc_dev_attrs[] = {
 	&dev_attr_device_id.attr,
 	&dev_attr_provides_device_sdrs.attr,
@@ -2886,6 +2918,7 @@ static struct attribute *bmc_dev_attrs[] = {
 	&dev_attr_product_id.attr,
 	&dev_attr_aux_firmware_revision.attr,
 	&dev_attr_guid.attr,
+	&dev_attr_user_count.attr,
 	NULL
 };
 
-- 
2.25.1