bonding: add sysfs /slave dir for bond slave devices.

Add sub-directory under /sys/class/net/<interface>/slave with
read-only attributes for slave.  Directory only appears when
<interface> is a slave.

$ tree /sys/class/net/eth2/slave/
/sys/class/net/eth2/slave/
├── ad_aggregator_id
├── link_failure_count
├── mii_status
├── perm_hwaddr
├── queue_id
└── state

$ cat /sys/class/net/eth2/slave/*
2
0
up
40:02:10:ef:06:01
0
active

Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 144 insertions, 0 deletions

diff --git a/drivers/net/bonding/bond_sysfs_slave.c b/drivers/net/bonding/bond_sysfs_slave.c
new file mode 100644
index 000000000000..7cb97de3cf63
--- /dev/null
+++ b/drivers/net/bonding/bond_sysfs_slave.c
@@ -0,0 +1,144 @@
+/*      Sysfs attributes of bond slaves
+ *
+ *      Copyright (c) 2014 Scott Feldman <sfeldma@cumulusnetworks.com>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/capability.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+
+#include "bonding.h"
+
+struct slave_attribute {
+        struct attribute attr;
+        ssize_t (*show)(struct slave *, char *);
+};
+
+#define SLAVE_ATTR(_name, _mode, _show)                         \
+const struct slave_attribute slave_attr_##_name = {             \
+        .attr = {.name = __stringify(_name),                    \
+                 .mode = _mode },                               \
+        .show   = _show,                                        \
+};
+#define SLAVE_ATTR_RO(_name) \
+        SLAVE_ATTR(_name, S_IRUGO, _name##_show)
+
+static ssize_t state_show(struct slave *slave, char *buf)
+{
+        switch (bond_slave_state(slave)) {
+        case BOND_STATE_ACTIVE:
+                return sprintf(buf, "active\n");
+        case BOND_STATE_BACKUP:
+                return sprintf(buf, "backup\n");
+        default:
+                return sprintf(buf, "UNKONWN\n");
+        }
+}
+static SLAVE_ATTR_RO(state);
+
+static ssize_t mii_status_show(struct slave *slave, char *buf)
+{
+        return sprintf(buf, "%s\n", bond_slave_link_status(slave->link));
+}
+static SLAVE_ATTR_RO(mii_status);
+
+static ssize_t link_failure_count_show(struct slave *slave, char *buf)
+{
+        return sprintf(buf, "%d\n", slave->link_failure_count);
+}
+static SLAVE_ATTR_RO(link_failure_count);
+
+static ssize_t perm_hwaddr_show(struct slave *slave, char *buf)
+{
+        return sprintf(buf, "%pM\n", slave->perm_hwaddr);
+}
+static SLAVE_ATTR_RO(perm_hwaddr);
+
+static ssize_t queue_id_show(struct slave *slave, char *buf)
+{
+        return sprintf(buf, "%d\n", slave->queue_id);
+}
+static SLAVE_ATTR_RO(queue_id);
+
+static ssize_t ad_aggregator_id_show(struct slave *slave, char *buf)
+{
+        const struct aggregator *agg;
+
+        if (slave->bond->params.mode == BOND_MODE_8023AD) {
+                agg = SLAVE_AD_INFO(slave).port.aggregator;
+                if (agg)
+                        return sprintf(buf, "%d\n",
+                                       agg->aggregator_identifier);
+        }
+
+        return sprintf(buf, "N/A\n");
+}
+static SLAVE_ATTR_RO(ad_aggregator_id);
+
+static const struct slave_attribute *slave_attrs[] = {
+        &slave_attr_state,
+        &slave_attr_mii_status,
+        &slave_attr_link_failure_count,
+        &slave_attr_perm_hwaddr,
+        &slave_attr_queue_id,
+        &slave_attr_ad_aggregator_id,
+        NULL
+};
+
+#define to_slave_attr(_at) container_of(_at, struct slave_attribute, attr)
+#define to_slave(obj)   container_of(obj, struct slave, kobj)
+
+static ssize_t slave_show(struct kobject *kobj,
+                          struct attribute *attr, char *buf)
+{
+        struct slave_attribute *slave_attr = to_slave_attr(attr);
+        struct slave *slave = to_slave(kobj);
+
+        return slave_attr->show(slave, buf);
+}
+
+const struct sysfs_ops slave_sysfs_ops = {
+        .show = slave_show,
+};
+
+static struct kobj_type slave_ktype = {
+#ifdef CONFIG_SYSFS
+        .sysfs_ops = &slave_sysfs_ops,
+#endif
+};
+
+int bond_sysfs_slave_add(struct slave *slave)
+{
+        const struct slave_attribute **a;
+        int err;
+
+        err = kobject_init_and_add(&slave->kobj, &slave_ktype,
+                                   &(slave->dev->dev.kobj), "slave");
+        if (err)
+                return err;
+
+        for (a = slave_attrs; *a; ++a) {
+                err = sysfs_create_file(&slave->kobj, &((*a)->attr));
+                if (err) {
+                        kobject_del(&slave->kobj);
+                        return err;
+                }
+        }
+
+        return 0;
+}
+
+void bond_sysfs_slave_del(struct slave *slave)
+{
+        const struct slave_attribute **a;
+
+        for (a = slave_attrs; *a; ++a)
+                sysfs_remove_file(&slave->kobj, &((*a)->attr));
+
+        kobject_del(&slave->kobj);
+}