sys/kern/kern_sysmsg.c

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/Attic/kern_sysmsg.c,v 1.6 2005/11/21 21:59:50 dillon Exp $
  35  */
  36
  37 /*
  38  * SYSMSG is our system call message encapsulation and handling subsystem.
  39  * System calls are now encapsulated in messages.  A system call can execute
  40  * synchronously or asynchronously.  If a system call wishes to run
  41  * asynchronously it returns EASYNC and the process records the pending system
  42  * call message in p_sysmsgq.
  43  *
  44  * SYSMSGs work similarly to LWKT messages in that the originator can request
  45  * a synchronous or asynchronous operation in isolation from the actual system
  46  * call which can choose to run the system call synchronous or asynchronously
  47  * (independant of what was requested).  Like LWKT messages, the synchronous
  48  * path avoids all queueing operations and is almost as fast as making a
  49  * direct procedure call.
  50  */
  51
  52 #include <sys/param.h>
  53 #include <sys/systm.h>
  54 #include <sys/proc.h>
  55 #include <sys/pioctl.h>
  56 #include <sys/kernel.h>
  57 #include <sys/resourcevar.h>
  58 #include <sys/signalvar.h>
  59 #include <sys/syscall.h>
  60 #include <sys/sysctl.h>
  61 #include <sys/sysent.h>
  62 #include <sys/uio.h>
  63 #include <sys/vmmeter.h>
  64 #include <sys/malloc.h>
  65 #ifdef KTRACE
  66 #include <sys/ktrace.h>
  67 #endif
  68 #include <sys/upcall.h>
  69 #include <sys/sysproto.h>
  70 #include <sys/sysunion.h>
  71
  72 #include <vm/vm.h>
  73 #include <vm/vm_param.h>
  74 #include <sys/lock.h>
  75 #include <vm/pmap.h>
  76 #include <vm/vm_kern.h>
  77 #include <vm/vm_map.h>
  78 #include <vm/vm_page.h>
  79 #include <vm/vm_extern.h>
  80
  81 #include <sys/msgport2.h>
  82 #include <sys/thread2.h>
  83
  84 /*
  85  * Sysctl to limit max in progress syscall messages per process. 0 for
  86  * unlimited.
  87  */
  88 int max_sysmsg = 0;
  89 SYSCTL_INT(_kern, OID_AUTO, max_sysmsg, CTLFLAG_RW, &max_sysmsg, 0,
  90                 "Max sysmsg's a process can have running");
  91
  92 /*
  93  * Wait for a system call message to be returned.  If NULL is passed we
  94  * wait for the next ready sysmsg and return it.  We return NULL if there
  95  * are no pending sysmsgs queued.
  96  *
  97  * NOTE: proc must be curproc.
  98  *
  99  * MPSAFE
 100  */
 101 struct sysmsg *
 102 sysmsg_wait(struct lwp *lp, struct sysmsg *sysmsg, int nonblock)
 103 {
 104         thread_t td = lp->lwp_thread;
 105
 106         /*
 107          * Get the next finished system call or the specified system call,
 108          * blocking until it is finished (if requested).
 109          */
 110         if (sysmsg == NULL) {
 111                 if (TAILQ_FIRST(&lp->lwp_sysmsgq) == NULL)
 112                         return(NULL);
 113                 if (nonblock) {
 114                         if ((sysmsg = lwkt_getport(&td->td_msgport)) == NULL)
 115                                 return(NULL);
 116                 } else {
 117                         sysmsg = lwkt_waitport(&td->td_msgport, NULL);
 118                 }
 119         } else {
 120                 if (nonblock && !lwkt_checkmsg(&sysmsg->lmsg))
 121                         return(NULL);
 122                 lwkt_waitport(&td->td_msgport, &sysmsg->lmsg);
 123         }
 124
 125         /*
 126          * sysmsg is not NULL here
 127          */
 128         TAILQ_REMOVE(&lp->lwp_sysmsgq, sysmsg, msgq);
 129         lp->lwp_nsysmsg--;
 130         return(sysmsg);
 131 }
 132
 133 /*
 134  * Wait for all pending asynchronous system calls to complete, aborting them
 135  * if requested (XXX).
 136  */
 137 void
 138 sysmsg_rundown(struct lwp *lp, int doabort)
 139 {
 140         struct sysmsg *sysmsg;
 141         thread_t td = lp->lwp_thread;
 142         globaldata_t gd = td->td_gd;
 143
 144         while (TAILQ_FIRST(&lp->lwp_sysmsgq) != NULL) {
 145                 printf("WAITSYSMSG\n");
 146                 sysmsg = sysmsg_wait(lp, NULL, 0);
 147                 printf("WAITSYSMSG %p\n", sysmsg);
 148                 KKASSERT(sysmsg != NULL);
 149                 /* XXX don't bother with pending copyouts */
 150                 /* XXX we really should do pending copyouts */
 151                 crit_enter_quick(td);
 152                 sysmsg->lmsg.opaque.ms_sysunnext = gd->gd_freesysun;
 153                 gd->gd_freesysun = (void *)sysmsg;
 154                 crit_exit_quick(td);
 155         }
 156 }
 157