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Commit e4447aef authored by Jayden Kim's avatar Jayden Kim
Browse files

Determine local mtu for offload LE socket 

The local MTU is selected as the minimum of:
  - The socket hal's offload capabilities
  - The application's requested maximum RX packet size

However, the MTU must be at least the minimum required by the L2CAP LE specification.

Bug: 342012881
Bug: 367419086
Test: m -j
Change-Id: Ia6360280b0527cb1218701d99a4ca424e38d83c9
parent 5c298722

system/btif/src/btif_sock_l2cap.cc

+37 −3
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ 
#include "gd/os/rand.h"

#include "include/hardware/bluetooth.h"

#include "internal_include/bt_target.h"

#include "lpp/lpp_offload_interface.h"

#include "main/shim/entry.h"

#include "osi/include/allocator.h"

#include "osi/include/osi.h"

#include "stack/include/bt_hdr.h"
@@ -868,12 +870,38 @@ static void btsock_l2cap_server_listen(l2cap_socket* sock) { 
                         sock->rx_mtu, std::move(cfg), btsock_l2cap_cbk, sock->id);

}



/*

 * Determine the local MTU for the offloaded L2CAP connection.

 *

 * The local MTU is selected as the minimum of:

 *   - The socket hal's offload capabilities (socket_cap.leCocCapabilities.mtu)

 *   - The application's requested maximum RX packet size (app_max_rx_packet_size)

 *

 * However, the MTU must be at least the minimum required by the L2CAP LE

 * specification (L2CAP_SDU_LENGTH_LE_MIN).

 */



static bool btsock_l2cap_get_offload_mtu(uint16_t* rx_mtu, uint16_t app_max_rx_packet_size) {

  hal::SocketCapabilities socket_cap =

          bluetooth::shim::GetLppOffloadManager()->GetSocketCapabilities();

  if (!socket_cap.le_coc_capabilities.number_of_supported_sockets) {

    return false;

  }

  /* Socket HAL client has already verified that the MTU is in a valid range. */

  uint16_t mtu = static_cast<uint16_t>(socket_cap.le_coc_capabilities.mtu);

  mtu = std::min(mtu, app_max_rx_packet_size);

  if (mtu < L2CAP_SDU_LENGTH_LE_MIN) {

    mtu = L2CAP_SDU_LENGTH_LE_MIN;

  }

  *rx_mtu = mtu;

  return true;

}



static bt_status_t btsock_l2cap_listen_or_connect(const char* name, const RawAddress* addr,

                                                  int channel, int* sock_fd, int flags, char listen,

                                                  int app_uid, btsock_data_path_t data_path,

                                                  const char* socket_name, uint64_t hub_id,

                                                  uint64_t endpoint_id,

                                                  int /* max_rx_packet_size */) {

                                                  uint64_t endpoint_id, int max_rx_packet_size) {

  if (!is_inited()) {

    return BT_STATUS_NOT_READY;

  }
@@ -911,7 +939,13 @@ static bt_status_t btsock_l2cap_listen_or_connect(const char* name, const RawAdd 
  sock->channel = channel;

  sock->app_uid = app_uid;

  sock->is_le_coc = is_le_coc;

  if (data_path == BTSOCK_DATA_PATH_HARDWARE_OFFLOAD) {

    if (!btsock_l2cap_get_offload_mtu(&sock->rx_mtu, static_cast<uint16_t>(max_rx_packet_size))) {

      return BT_STATUS_UNSUPPORTED;

    }

  } else {

    sock->rx_mtu = is_le_coc ? L2CAP_SDU_LENGTH_LE_MAX : L2CAP_SDU_LENGTH_MAX;

  }

  sock->data_path = data_path;

  if (socket_name) {

    strncpy(sock->socket_name, socket_name, sizeof(sock->socket_name) - 1);

system/stack/include/l2cdefs.h

+1 −0
Original line number Diff line number Diff line
@@ -487,6 +487,7 @@ inline std::string l2cap_cfg_result_text(const tL2CAP_CFG_RESULT& result) { 
 */

#define L2CAP_SDU_LENGTH_MAX (8080 + 26 - (L2CAP_MIN_OFFSET + 6))

constexpr uint16_t L2CAP_SDU_LENGTH_LE_MAX = 0xffff;

constexpr uint16_t L2CAP_SDU_LENGTH_LE_MIN = 23;



/* SAR bits in the control word

 */

system/stack/l2cap/l2c_ble.cc

+2 −3
Original line number Diff line number Diff line
@@ -777,9 +777,8 @@ void l2cble_process_sig_cmd(tL2C_LCB* p_lcb, uint8_t* p, uint16_t pkt_len) { 
      p_ccb->p_rcb = p_rcb;

      p_ccb->remote_cid = rcid;



      p_ccb->local_conn_cfg.mtu = L2CAP_SDU_LENGTH_LE_MAX;

      p_ccb->local_conn_cfg.mps =

              bluetooth::shim::GetController()->GetLeBufferSize().le_data_packet_length_;

      p_ccb->local_conn_cfg.mtu = p_rcb->coc_cfg.mtu;

      p_ccb->local_conn_cfg.mps = p_rcb->coc_cfg.mps;

      p_ccb->local_conn_cfg.credits = p_rcb->coc_cfg.credits;



      p_ccb->remote_credit_count = p_rcb->coc_cfg.credits;