lwp/preempt.c

   1 /*
   2 ****************************************************************************
   3 *        Copyright IBM Corporation 1988, 1989 - All Rights Reserved        *
   4 *                                                                          *
   5 * Permission to use, copy, modify, and distribute this software and its    *
   6 * documentation for any purpose and without fee is hereby granted,         *
   7 * provided that the above copyright notice appear in all copies and        *
   8 * that both that copyright notice and this permission notice appear in     *
   9 * supporting documentation, and that the name of IBM not be used in        *
  10 * advertising or publicity pertaining to distribution of the software      *
  11 * without specific, written prior permission.                              *
  12 *                                                                          *
  13 * IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL *
  14 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL IBM *
  15 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY      *
  16 * DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER  *
  17 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING   *
  18 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.    *
  19 ****************************************************************************
  20 */
  21
  22 /*******************************************************************\
  23 *                                                                   *
  24 *       Information Technology Center                               *
  25 *       Carnegie-Mellon University                                  *
  26 *                                                                   *
  27 *       Bradley White and M. Satyanarayanan                         *
  28 \*******************************************************************/
  29
  30 #include <sys/time.h>
  31 #include <signal.h>
  32 #include <lwp.h>
  33 #include "preempt.h"
  34
  35 RCSID("$Id$");
  36
  37 sig_atomic_t PRE_Block = 0;             /* used in lwp.c and process.s */
  38
  39 #ifdef HAVE_GETITIMER
  40
  41 static RETSIGTYPE
  42 #if defined(AFS_POSIX_SIGNALS)
  43 AlarmHandler(int sig)
  44 #else
  45 AlarmHandler(int sig, int code, struct sigcontext *scp)
  46 #endif
  47 {
  48 #ifdef AFS_POSIX_SIGNALS
  49     sigset_t mask ;
  50 #endif
  51
  52     if (PRE_Block == 0 && lwp_cpptr->level == 0) {
  53         PRE_BeginCritical();
  54 #if defined(AFS_POSIX_SIGNALS)
  55         sigemptyset(&mask);
  56         sigaddset(&mask, sig);
  57         sigprocmask(SIG_UNBLOCK, &mask, (sigset_t *)0);
  58 #else
  59         sigsetmask(scp->sc_mask);
  60 #endif
  61         LWP_DispatchProcess();
  62         PRE_EndCritical();
  63     }
  64
  65 }
  66
  67
  68
  69 int
  70 PRE_InitPreempt(struct timeval *slice)
  71 {
  72     struct itimerval itv;
  73 #ifdef AFS_POSIX_SIGNALS
  74     struct sigaction sa;
  75 #else
  76     struct sigvec vec;
  77 #endif
  78
  79     if (lwp_cpptr == 0) return (LWP_EINIT);
  80
  81     if (slice == 0) {
  82         itv.it_interval.tv_sec = itv.it_value.tv_sec = DEFAULTSLICE;
  83         itv.it_interval.tv_usec = itv.it_value.tv_usec = 0;
  84     } else {
  85         itv.it_interval = itv.it_value = *slice;
  86     }
  87
  88 #ifdef AFS_POSIX_SIGNALS
  89     sa.sa_handler = AlarmHandler;
  90 #ifndef SA_NODEFER
  91 #define SA_NODEFER 0
  92 #endif
  93 #ifdef SA_SIGINFO
  94     sa.sa_flags = SA_SIGINFO|SA_NODEFER;
  95 #else
  96     sa.sa_flags = SA_NODEFER;
  97 #endif
  98
  99     if ((sigaction(SIGALRM, &sa, (struct sigaction *)0) == -1) ||
 100         (setitimer(ITIMER_REAL, &itv, (struct itimerval *) 0) == -1))
 101         return(LWP_ESYSTEM);
 102 #else
 103     vec.sv_handler = AlarmHandler;
 104     vec.sv_mask = vec.sv_onstack = 0;
 105
 106     if ((sigvec(SIGALRM, &vec, (struct sigvec *)0) == -1) ||
 107         (setitimer(ITIMER_REAL, &itv, (struct itimerval *) 0) == -1))
 108         return(LWP_ESYSTEM);
 109 #endif
 110
 111     return(LWP_SUCCESS);
 112 }
 113
 114 int
 115 PRE_EndPreempt(void)
 116 {
 117     struct itimerval itv;
 118 #ifdef AFS_POSIX_SIGNALS
 119     struct sigaction sa;
 120 #else
 121     struct sigvec vec;
 122 #endif
 123
 124     if (lwp_cpptr == 0)
 125         return (LWP_EINIT);
 126
 127     itv.it_value.tv_sec = itv.it_value.tv_usec = 0;
 128
 129 #ifdef AFS_POSIX_SIGNALS
 130     sa.sa_handler = SIG_DFL;
 131     sa.sa_flags=0;
 132
 133     if ((setitimer(ITIMER_REAL, &itv, (struct itimerval *) 0) == -1) ||
 134         (sigaction(SIGALRM, &sa, (struct sigaction *)0) == -1))
 135         return(LWP_ESYSTEM);
 136 #else
 137     vec.sv_handler = SIG_DFL;;
 138     vec.sv_mask = vec.sv_onstack = 0;
 139
 140     if ((setitimer(ITIMER_REAL, &itv, (struct itimerval *) 0) == -1) ||
 141         (sigvec(SIGALRM, &vec, (struct sigvec *)0) == -1))
 142         return(LWP_ESYSTEM);
 143 #endif
 144
 145     return(LWP_SUCCESS);
 146 }
 147
 148 #else /* !HAVE_GETITIMER */
 149
 150 int
 151 PRE_InitPreempt(struct timeval *slice)
 152 {
 153     return LWP_SUCCESS;
 154 }
 155
 156 int
 157 PRE_EndPreempt(void)
 158 {
 159     return LWP_SUCCESS;
 160 }
 161
 162 #endif /* HAVE_GETITIMER */