nimble/host: Rework locking in L2CAP

Main goal here to cleanup how locking is being done in L2CAP code:
 - avoid double/nested locking
 - avoid lock-unlock-lock pattern due to public API calls from
   internal code
 - provide _nolock variants to be used internally
 - public API is locked wrapper around _nolock private API
 - avoid locking in FOO and unlocking in BAR function for code clarify

Author: sjanc

nimble/host/src/ble_l2cap.c

@@ -152,7 +152,13 @@ int
 ble_l2cap_connect(uint16_t conn_handle, uint16_t psm, uint16_t mtu,
                   struct os_mbuf *sdu_rx, ble_l2cap_event_fn *cb, void *cb_arg)
 {
-    return ble_l2cap_sig_coc_connect(conn_handle, psm, mtu, sdu_rx, cb, cb_arg);
+    int rc;
+
+    ble_hs_lock();
+    rc = ble_l2cap_sig_connect_nolock(conn_handle, psm, mtu, sdu_rx, cb, cb_arg);
+    ble_hs_unlock();
+
+    return rc;
 }
 
 int
@@ -183,15 +189,22 @@ ble_l2cap_enhanced_connect(uint16_t conn_handle,
                                uint8_t num, struct os_mbuf *sdu_rx[],
                                ble_l2cap_event_fn *cb, void *cb_arg)
 {
-    return ble_l2cap_sig_ecoc_connect(conn_handle, psm, mtu,
-                                      num, sdu_rx, cb, cb_arg);
+    int rc;
+
+    ble_hs_lock();
+    rc = ble_l2cap_sig_ecoc_connect_nolock(conn_handle, psm, mtu, num, sdu_rx,
+                                           cb, cb_arg);
+    ble_hs_unlock();
+
+    return rc;
 }
 
 int
 ble_l2cap_reconfig(struct ble_l2cap_chan *chans[], uint8_t num, uint16_t new_mtu)
 {
     int i;
     uint16_t conn_handle;
+    int rc;
 
     if (num == 0 || !chans) {
         return BLE_HS_EINVAL;
@@ -206,13 +219,23 @@ ble_l2cap_reconfig(struct ble_l2cap_chan *chans[], uint8_t num, uint16_t new_mtu
         }
     }
 
-    return ble_l2cap_sig_coc_reconfig(conn_handle, chans, num, new_mtu);
+    ble_hs_lock();
+    rc = ble_l2cap_sig_coc_reconfig_nolock(conn_handle, chans, num, new_mtu);
+    ble_hs_unlock();
+
+    return rc;
 }
 
 int
 ble_l2cap_disconnect(struct ble_l2cap_chan *chan)
 {
-    return ble_l2cap_sig_disconnect(chan);
+    int rc;
+
+    ble_hs_lock();
+    rc = ble_l2cap_sig_disconnect_nolock(chan);
+    ble_hs_unlock();
+
+    return rc;
 }
 
 /**

nimble/host/src/ble_l2cap_coc.c

@@ -599,8 +599,8 @@ ble_l2cap_coc_le_credits_update(uint16_t conn_handle, uint16_t dcid,
 
     if (chan->coc_tx.credits + credits > 0xFFFF) {
         BLE_HS_LOG(INFO, "LE CoC credits overflow...disconnecting\n");
+        ble_l2cap_sig_disconnect_nolock(chan);
         ble_hs_unlock();
-        ble_l2cap_sig_disconnect(chan);
         return;
     }