Bluetooth: Convert LTK list to RCU

This patch set converts the hdev->long_term_keys list to use RCU to
eliminate the need to use hci_dev_lock/unlock.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

3 files changed, 30 insertions, 26 deletions

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 6c162c8809cf..c9495fb9f595 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -778,17 +778,15 @@ static const struct file_operations identity_resolving_keys_fops = {
 static int long_term_keys_show(struct seq_file *f, void *ptr)
 {
         struct hci_dev *hdev = f->private;
-        struct list_head *p, *n;
+        struct smp_ltk *ltk;
 
-        hci_dev_lock(hdev);
-        list_for_each_safe(p, n, &hdev->long_term_keys) {
-                struct smp_ltk *ltk = list_entry(p, struct smp_ltk, list);
+        rcu_read_lock();
+        list_for_each_entry_rcu(ltk, &hdev->long_term_keys, list)
                 seq_printf(f, "%pMR (type %u) %u 0x%02x %u %.4x %.16llx %*phN\n",
                            &ltk->bdaddr, ltk->bdaddr_type, ltk->authenticated,
                            ltk->type, ltk->enc_size, __le16_to_cpu(ltk->ediv),
                            __le64_to_cpu(ltk->rand), 16, ltk->val);
-        }
-        hci_dev_unlock(hdev);
+        rcu_read_unlock();
 
         return 0;
 }
@@ -3106,11 +3104,11 @@ void hci_link_keys_clear(struct hci_dev *hdev)
 
 void hci_smp_ltks_clear(struct hci_dev *hdev)
 {
-        struct smp_ltk *k, *tmp;
+        struct smp_ltk *k;
 
-        list_for_each_entry_safe(k, tmp, &hdev->long_term_keys, list) {
-                list_del(&k->list);
-                kfree(k);
+        list_for_each_entry_rcu(k, &hdev->long_term_keys, list) {
+                list_del_rcu(&k->list);
+                kfree_rcu(k, rcu);
         }
 }
 
@@ -3184,15 +3182,18 @@ struct smp_ltk *hci_find_ltk(struct hci_dev *hdev, __le16 ediv, __le64 rand,
 {
         struct smp_ltk *k;
 
-        list_for_each_entry(k, &hdev->long_term_keys, list) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(k, &hdev->long_term_keys, list) {
                 if (k->ediv != ediv || k->rand != rand)
                         continue;
 
                 if (ltk_role(k->type) != role)
                         continue;
 
+                rcu_read_unlock();
                 return k;
         }
+        rcu_read_unlock();
 
         return NULL;
 }
@@ -3202,11 +3203,16 @@ struct smp_ltk *hci_find_ltk_by_addr(struct hci_dev *hdev, bdaddr_t *bdaddr,
 {
         struct smp_ltk *k;
 
-        list_for_each_entry(k, &hdev->long_term_keys, list)
+        rcu_read_lock();
+        list_for_each_entry_rcu(k, &hdev->long_term_keys, list) {
                 if (addr_type == k->bdaddr_type &&
                     bacmp(bdaddr, &k->bdaddr) == 0 &&
-                    ltk_role(k->type) == role)
+                    ltk_role(k->type) == role) {
+                        rcu_read_unlock();
                         return k;
+                }
+        }
+        rcu_read_unlock();
 
         return NULL;
 }
@@ -3309,7 +3315,7 @@ struct smp_ltk *hci_add_ltk(struct hci_dev *hdev, bdaddr_t *bdaddr,
                 key = kzalloc(sizeof(*key), GFP_KERNEL);
                 if (!key)
                         return NULL;
-                list_add(&key->list, &hdev->long_term_keys);
+                list_add_rcu(&key->list, &hdev->long_term_keys);
         }
 
         bacpy(&key->bdaddr, bdaddr);
@@ -3365,17 +3371,17 @@ int hci_remove_link_key(struct hci_dev *hdev, bdaddr_t *bdaddr)
 
 int hci_remove_ltk(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 bdaddr_type)
 {
-        struct smp_ltk *k, *tmp;
+        struct smp_ltk *k;
         int removed = 0;
 
-        list_for_each_entry_safe(k, tmp, &hdev->long_term_keys, list) {
+        list_for_each_entry_rcu(k, &hdev->long_term_keys, list) {
                 if (bacmp(bdaddr, &k->bdaddr) || k->bdaddr_type != bdaddr_type)
                         continue;
 
                 BT_DBG("%s removing %pMR", hdev->name, bdaddr);
 
-                list_del(&k->list);
-                kfree(k);
+                list_del_rcu(&k->list);
+                kfree_rcu(k, rcu);
                 removed++;
         }
 
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index aec3b1dce1cc..09d76547d985 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -4578,8 +4578,8 @@ static void hci_le_ltk_request_evt(struct hci_dev *hdev, struct sk_buff *skb)
          */
         if (ltk->type == SMP_STK) {
                 set_bit(HCI_CONN_STK_ENCRYPT, &conn->flags);
-                list_del(&ltk->list);
-                kfree(ltk);
+                list_del_rcu(&ltk->list);
+                kfree_rcu(ltk, rcu);
         } else {
                 clear_bit(HCI_CONN_STK_ENCRYPT, &conn->flags);
         }
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 3dc5f0e66405..fd2dfe5222bc 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -383,13 +383,13 @@ static void smp_chan_destroy(struct l2cap_conn *conn)
         /* If pairing failed clean up any keys we might have */
         if (!complete) {
                 if (smp->ltk) {
-                        list_del(&smp->ltk->list);
-                        kfree(smp->ltk);
+                        list_del_rcu(&smp->ltk->list);
+                        kfree_rcu(smp->ltk, rcu);
                 }
 
                 if (smp->slave_ltk) {
-                        list_del(&smp->slave_ltk->list);
-                        kfree(smp->slave_ltk);
+                        list_del_rcu(&smp->slave_ltk->list);
+                        kfree_rcu(smp->slave_ltk, rcu);
                 }
 
                 if (smp->remote_irk) {
@@ -1321,7 +1321,6 @@ static int smp_cmd_master_ident(struct l2cap_conn *conn, struct sk_buff *skb)
 
         skb_pull(skb, sizeof(*rp));
 
-        hci_dev_lock(hdev);
         authenticated = (hcon->sec_level == BT_SECURITY_HIGH);
         ltk = hci_add_ltk(hdev, &hcon->dst, hcon->dst_type, SMP_LTK,
                           authenticated, smp->tk, smp->enc_key_size,
@@ -1329,7 +1328,6 @@ static int smp_cmd_master_ident(struct l2cap_conn *conn, struct sk_buff *skb)
         smp->ltk = ltk;
         if (!(smp->remote_key_dist & KEY_DIST_MASK))
                 smp_distribute_keys(smp);
-        hci_dev_unlock(hdev);
 
         return 0;
 }