Bluetooth: convert conn hash to RCU
Gustavo F. Padovan [Thu, 15 Dec 2011 00:54:12 +0000 (22:54 -0200)]
Handling hci_conn_hash with RCU make us avoid some locking and disable
tasklets.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/hci_core.h
net/bluetooth/hci_conn.c
net/bluetooth/hci_core.c

index 14b200b..e832433 100644 (file)
@@ -392,7 +392,7 @@ static inline void hci_conn_hash_init(struct hci_dev *hdev)
 static inline void hci_conn_hash_add(struct hci_dev *hdev, struct hci_conn *c)
 {
        struct hci_conn_hash *h = &hdev->conn_hash;
-       list_add(&c->list, &h->list);
+       list_add_rcu(&c->list, &h->list);
        switch (c->type) {
        case ACL_LINK:
                h->acl_num++;
@@ -410,7 +410,10 @@ static inline void hci_conn_hash_add(struct hci_dev *hdev, struct hci_conn *c)
 static inline void hci_conn_hash_del(struct hci_dev *hdev, struct hci_conn *c)
 {
        struct hci_conn_hash *h = &hdev->conn_hash;
-       list_del(&c->list);
+
+       list_del_rcu(&c->list);
+       synchronize_rcu();
+
        switch (c->type) {
        case ACL_LINK:
                h->acl_num--;
@@ -445,14 +448,18 @@ static inline struct hci_conn *hci_conn_hash_lookup_handle(struct hci_dev *hdev,
                                                                __u16 handle)
 {
        struct hci_conn_hash *h = &hdev->conn_hash;
-       struct list_head *p;
        struct hci_conn  *c;
 
-       list_for_each(p, &h->list) {
-               c = list_entry(p, struct hci_conn, list);
-               if (c->handle == handle)
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(c, &h->list, list) {
+               if (c->handle == handle) {
+                       rcu_read_unlock();
                        return c;
+               }
        }
+       rcu_read_unlock();
+
        return NULL;
 }
 
@@ -460,14 +467,19 @@ static inline struct hci_conn *hci_conn_hash_lookup_ba(struct hci_dev *hdev,
                                                        __u8 type, bdaddr_t *ba)
 {
        struct hci_conn_hash *h = &hdev->conn_hash;
-       struct list_head *p;
        struct hci_conn  *c;
 
-       list_for_each(p, &h->list) {
-               c = list_entry(p, struct hci_conn, list);
-               if (c->type == type && !bacmp(&c->dst, ba))
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(c, &h->list, list) {
+               if (c->type == type && !bacmp(&c->dst, ba)) {
+                       rcu_read_unlock();
                        return c;
+               }
        }
+
+       rcu_read_unlock();
+
        return NULL;
 }
 
@@ -475,14 +487,19 @@ static inline struct hci_conn *hci_conn_hash_lookup_state(struct hci_dev *hdev,
                                                        __u8 type, __u16 state)
 {
        struct hci_conn_hash *h = &hdev->conn_hash;
-       struct list_head *p;
        struct hci_conn  *c;
 
-       list_for_each(p, &h->list) {
-               c = list_entry(p, struct hci_conn, list);
-               if (c->type == type && c->state == state)
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(c, &h->list, list) {
+               if (c->type == type && c->state == state) {
+                       rcu_read_unlock();
                        return c;
+               }
        }
+
+       rcu_read_unlock();
+
        return NULL;
 }
 
index b044676..5e9e193 100644 (file)
@@ -418,18 +418,17 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst)
 
        hci_dev_hold(hdev);
 
-       tasklet_disable(&hdev->tx_task);
-
        hci_conn_hash_add(hdev, conn);
-       if (hdev->notify)
+       if (hdev->notify) {
+               tasklet_disable(&hdev->tx_task);
                hdev->notify(hdev, HCI_NOTIFY_CONN_ADD);
+               tasklet_enable(&hdev->tx_task);
+       }
 
        atomic_set(&conn->devref, 0);
 
        hci_conn_init_sysfs(conn);
 
-       tasklet_enable(&hdev->tx_task);
-
        return conn;
 }
 
@@ -465,15 +464,15 @@ int hci_conn_del(struct hci_conn *conn)
                }
        }
 
-       tasklet_disable(&hdev->tx_task);
 
        hci_chan_list_flush(conn);
 
        hci_conn_hash_del(hdev, conn);
-       if (hdev->notify)
+       if (hdev->notify) {
+               tasklet_disable(&hdev->tx_task);
                hdev->notify(hdev, HCI_NOTIFY_CONN_DEL);
-
-       tasklet_enable(&hdev->tx_task);
+               tasklet_enable(&hdev->tx_task);
+       }
 
        skb_queue_purge(&conn->data_q);
 
@@ -808,7 +807,7 @@ void hci_conn_hash_flush(struct hci_dev *hdev)
 
        BT_DBG("hdev %s", hdev->name);
 
-       list_for_each_entry(c, &h->list, list) {
+       list_for_each_entry_rcu(c, &h->list, list) {
                c->state = BT_CLOSED;
 
                hci_proto_disconn_cfm(c, HCI_ERROR_LOCAL_HOST_TERM);
index 2c4f32f..de923ee 100644 (file)
@@ -2050,7 +2050,10 @@ static inline struct hci_conn *hci_low_sent(struct hci_dev *hdev, __u8 type, int
 
        /* We don't have to lock device here. Connections are always
         * added and removed with TX task disabled. */
-       list_for_each_entry(c, &h->list, list) {
+
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(c, &h->list, list) {
                if (c->type != type || skb_queue_empty(&c->data_q))
                        continue;
 
@@ -2068,6 +2071,8 @@ static inline struct hci_conn *hci_low_sent(struct hci_dev *hdev, __u8 type, int
                        break;
        }
 
+       rcu_read_unlock();
+
        if (conn) {
                int cnt, q;
 
@@ -2103,14 +2108,18 @@ static inline void hci_link_tx_to(struct hci_dev *hdev, __u8 type)
 
        BT_ERR("%s link tx timeout", hdev->name);
 
+       rcu_read_lock();
+
        /* Kill stalled connections */
-       list_for_each_entry(c, &h->list, list) {
+       list_for_each_entry_rcu(c, &h->list, list) {
                if (c->type == type && c->sent) {
                        BT_ERR("%s killing stalled connection %s",
                                hdev->name, batostr(&c->dst));
                        hci_acl_disconn(c, 0x13);
                }
        }
+
+       rcu_read_unlock();
 }
 
 static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
@@ -2124,7 +2133,9 @@ static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
 
        BT_DBG("%s", hdev->name);
 
-       list_for_each_entry(conn, &h->list, list) {
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(conn, &h->list, list) {
                struct hci_chan *tmp;
 
                if (conn->type != type)
@@ -2135,8 +2146,6 @@ static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
 
                conn_num++;
 
-               rcu_read_lock();
-
                list_for_each_entry_rcu(tmp, &conn->chan_list, list) {
                        struct sk_buff *skb;
 
@@ -2161,12 +2170,12 @@ static inline struct hci_chan *hci_chan_sent(struct hci_dev *hdev, __u8 type,
                        }
                }
 
-               rcu_read_unlock();
-
                if (hci_conn_num(hdev, type) == conn_num)
                        break;
        }
 
+       rcu_read_unlock();
+
        if (!chan)
                return NULL;
 
@@ -2200,7 +2209,9 @@ static void hci_prio_recalculate(struct hci_dev *hdev, __u8 type)
 
        BT_DBG("%s", hdev->name);
 
-       list_for_each_entry(conn, &h->list, list) {
+       rcu_read_lock();
+
+       list_for_each_entry_rcu(conn, &h->list, list) {
                struct hci_chan *chan;
 
                if (conn->type != type)
@@ -2211,8 +2222,6 @@ static void hci_prio_recalculate(struct hci_dev *hdev, __u8 type)
 
                num++;
 
-               rcu_read_lock();
-
                list_for_each_entry_rcu(chan, &conn->chan_list, list) {
                        struct sk_buff *skb;
 
@@ -2234,11 +2243,12 @@ static void hci_prio_recalculate(struct hci_dev *hdev, __u8 type)
                                                                skb->priority);
                }
 
-               rcu_read_unlock();
-
                if (hci_conn_num(hdev, type) == num)
                        break;
        }
+
+       rcu_read_unlock();
+
 }
 
 static inline void hci_sched_acl(struct hci_dev *hdev)