ABB semaphore protection overhaul The ABB semaphone protection logic that came with TCS211 from TI was broken in several ways: * Some semaphore-protected functions were called from Application_Initialize() context. NU_Obtain_Semaphore() called with NU_SUSPEND fails with NU_INVALID_SUSPEND in this context, but the return value wasn't checked, and NU_Release_Semaphore() would be called unconditionally at the end. The latter call would increment the semaphore count past 1, making the semaphore no longer binary and thus no longer effective for resource protection. The fix is to check the return value from NU_Obtain_Semaphore() and skip the NU_Release_Semaphore() call if the semaphore wasn't properly obtained. * Some SPI hardware manipulation was being done before entering the semaphore- protected critical section. The fix is to reorder the code: first obtain the semaphore, then do everything else. * In the corner case of L1/DSP recovery, l1_abb_power_on() would call some non-semaphore-protected ABB & SPI init functions. The fix is to skip those calls in the case of recovery. * A few additional corner cases existed, all of which are fixed by making ABB semaphore protection 100% consistent for all ABB functions and code paths. There is still one remaining problem of priority inversion: suppose a low- priority task calls an ABB function, and some medium-priority task just happens to preempt right in the middle of that semaphore-protected ABB operation. Then the high-priority SPI task is locked out for a non-deterministic time until that medium-priority task finishes its work and goes back to sleep. This priority inversion problem remains outstanding for now.

/**
 * @file    rnet_rt_api_getproto.c
 *
 * RNET_RT API
 *
 * @author  Regis Feneon
 * @version 0.1
 */

/*
 * $Id: rnet_rt_api_getproto.c,v 1.3 2002/10/30 15:23:34 rf Exp $
 * $Name: ti_20021030 $
 *
 * History:
 *
 *  Date        Author        Modification
 *  --------------------------------------------------
 *  3/29/2002   Regis Feneon  Create
 *
 * (C) Copyright 2002 by TI, All Rights Reserved
 *
 */

#include "rnet_cfg.h"
#ifdef RNET_CFG_REAL_TRANSPORT

#include "rnet_rt_i.h"
#include "rnet_rt_env.h"

/*
 * Retrieves the protocol associated to a connection descriptor.
 * The protocol is retrieved with the SO_TYPE socket option.
 *
 * @param  desc  Connection identifier.
 * @return  A value of the T_RNET_IPPROTO enumeration.
 */

T_RNET_IPPROTO rnet_rt_get_proto (T_RNET_DESC *desc)
{
  int err, len, type;

  len = sizeof( type);

  /* get type of socket */
  rvf_lock_mutex( &rnet_rt_env_ctrl_blk_p->mutex);
  err = ngSAIOGetOption( (NGsock *) desc, NG_IOCTL_SOCKET, NG_SO_TYPE,
    &type, &len);
  rvf_unlock_mutex( &rnet_rt_env_ctrl_blk_p->mutex);

  if( err == NG_EOK) {
    switch( type) {
    case NG_SOCK_STREAM:
      return( RNET_IPPROTO_TCP);
    case NG_SOCK_DGRAM:
      return( RNET_IPPROTO_UDP);
    default:
      break;
    }
  }

  /* should not happen... */
  return( RNET_IPPROTO_UNDEFINED);
}

#endif /* ifdef RNET_CFG_REAL_TRANSPORT */