fixes for fp context switching

[unix-history] / usr / src / sys / kern / kern_fork.c

diff --git a/usr/src/sys/kern/kern_fork.c b/usr/src/sys/kern/kern_fork.c
index 7eccd13..0ad02c0 100644 (file)
--- a/usr/src/sys/kern/kern_fork.c
+++ b/usr/src/sys/kern/kern_fork.c
@@ -1,37 +1,32 @@
 /*
 /*

- * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
+ * Copyright (c) 1982, 1986, 1989, 1991 Regents of the University of California.

  * All rights reserved.
  *
  * %sccs.include.redist.c%
  *
  * All rights reserved.
  *
  * %sccs.include.redist.c%
  *

- *     @(#)kern_fork.c 7.22 (Berkeley) %G%
+ *     @(#)kern_fork.c 7.30 (Berkeley) %G%

  */
 
 #include "param.h"
 #include "systm.h"
 #include "map.h"
  */
 
 #include "param.h"
 #include "systm.h"
 #include "map.h"

-#include "user.h"
+#include "filedesc.h"

 #include "kernel.h"
 #include "kernel.h"

+#include "malloc.h"

 #include "proc.h"
 #include "proc.h"

+#include "resourcevar.h"

 #include "vnode.h"
 #include "seg.h"
 #include "file.h"
 #include "acct.h"
 #include "ktrace.h"
 
 #include "vnode.h"
 #include "seg.h"
 #include "file.h"
 #include "acct.h"
 #include "ktrace.h"
 

-#include "machine/reg.h"
-#include "machine/psl.h"
-
-/*
- * fork system call.
- */

 /* ARGSUSED */
 fork(p, uap, retval)
        struct proc *p;
 /* ARGSUSED */
 fork(p, uap, retval)
        struct proc *p;

-       struct args *uap;
+       void *uap;

        int retval[];
 {
        int retval[];
 {

-       int error;

 
        return (fork1(p, 0, retval));
 }
 
        return (fork1(p, 0, retval));
 }


@@ -39,248 +34,237 @@ fork(p, uap, retval)
 /* ARGSUSED */
 vfork(p, uap, retval)
        struct proc *p;
 /* ARGSUSED */
 vfork(p, uap, retval)
        struct proc *p;

-       struct args *uap;
+       void *uap;

        int retval[];
 {
 
        return (fork1(p, 1, retval));
 }
 
        int retval[];
 {
 
        return (fork1(p, 1, retval));
 }
 

+int    nprocs = 1;             /* process 0 */
+

 fork1(p1, isvfork, retval)
        register struct proc *p1;
        int isvfork, retval[];
 {
        register struct proc *p2;
 fork1(p1, isvfork, retval)
        register struct proc *p1;
        int isvfork, retval[];
 {
        register struct proc *p2;

-       register int a;
+       register int count, uid;
+       static int nextpid, pidchecked = 0;

 
 

-       a = 0;
-       if (p1->p_uid != 0) {
+       count = 0;
+       if ((uid = p1->p_ucred->cr_uid) != 0) {

                for (p2 = allproc; p2; p2 = p2->p_nxt)
                for (p2 = allproc; p2; p2 = p2->p_nxt)

-                       if (p2->p_uid == p1->p_uid)
-                               a++;
+                       if (p2->p_ucred->cr_uid == uid)
+                               count++;

                for (p2 = zombproc; p2; p2 = p2->p_nxt)
                for (p2 = zombproc; p2; p2 = p2->p_nxt)

-                       if (p2->p_uid == p1->p_uid)
-                               a++;
+                       if (p2->p_ucred->cr_uid == uid)
+                               count++;

        }
        /*
        }
        /*

-        * Disallow if
-        *  No processes at all;
-        *  not su and too many procs owned; or
-        *  not su and would take last slot.
+        * Although process entries are dynamically created,
+        * we still keep a global limit on the maximum number
+        * we will create.  Don't allow a nonprivileged user
+        * to exceed its current limit or to bring us within one
+        * of the global limit; don't let root exceed the limit.
+        * nprocs is the current number of processes,
+        * maxproc is the limit.

         */
         */

-       p2 = freeproc;
-       if (p2==NULL)
+       if (nprocs >= maxproc || uid == 0 && nprocs >= maxproc + 1) {

                tablefull("proc");
                tablefull("proc");

-       if (p2 == NULL ||
-           (p1->p_uid != 0 && (p2->p_nxt == NULL || a > MAXUPRC))) {
-               retval[1] = 0;

                return (EAGAIN);
        }
                return (EAGAIN);
        }

-       if (newproc(isvfork)) {
-               retval[0] = p1->p_pid;
-               retval[1] = 1;  /* child */
-               u.u_acflag = AFORK;
-               return (0);
-       }
-       retval[0] = p2->p_pid;
-       retval[1] = 0;
-       return (0);
-}
-
-/*
- * Create a new process-- the internal version of
- * sys fork.
- * It returns 1 in the new process, 0 in the old.
- */
-newproc(isvfork)
-       int isvfork;
-{
-       register struct proc *rpp, *rip;
-       register int n;
-       register struct file *fp;
-       static int pidchecked = 0;
+       if (count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur)
+               return (EAGAIN);

 
        /*
 
        /*

-        * First, just locate a slot for a process
-        * and copy the useful info from this process into it.
-        * The panic "cannot happen" because fork has already
-        * checked for the existence of a slot.
+        * Find an unused process ID.
+        * We remember a range of unused IDs ready to use
+        * (from nextpid+1 through pidchecked-1).

         */
         */

-       mpid++;
+       nextpid++;

 retry:
 retry:

-       if (mpid >= PID_MAX) {
-               mpid = 100;
+       /*
+        * If the process ID prototype has wrapped around,
+        * restart somewhat above 0, as the low-numbered procs
+        * tend to include daemons that don't exit.
+        */
+       if (nextpid >= PID_MAX) {
+               nextpid = 100;

                pidchecked = 0;
        }
                pidchecked = 0;
        }

-       if (mpid >= pidchecked) {
+       if (nextpid >= pidchecked) {

                int doingzomb = 0;
 
                pidchecked = PID_MAX;
                /*
                int doingzomb = 0;
 
                pidchecked = PID_MAX;
                /*

-                * Scan the proc table to check whether this pid
+                * Scan the active and zombie procs to check whether this pid

                 * is in use.  Remember the lowest pid that's greater
                 * is in use.  Remember the lowest pid that's greater

-                * than mpid, so we can avoid checking for a while.
+                * than nextpid, so we can avoid checking for a while.

                 */
                 */

-               rpp = allproc;
+               p2 = allproc;

 again:
 again:

-               for (; rpp != NULL; rpp = rpp->p_nxt) {
-                       if (rpp->p_pid == mpid || rpp->p_pgrp->pg_id == mpid) {
-                               mpid++;
-                               if (mpid >= pidchecked)
+               for (; p2 != NULL; p2 = p2->p_nxt) {
+                       if (p2->p_pid == nextpid ||
+                           p2->p_pgrp->pg_id == nextpid) {
+                               nextpid++;
+                               if (nextpid >= pidchecked)

                                        goto retry;
                        }
                                        goto retry;
                        }

-                       if (rpp->p_pid > mpid && pidchecked > rpp->p_pid)
-                               pidchecked = rpp->p_pid;
-                       if (rpp->p_pgrp->pg_id > mpid && 
-                           pidchecked > rpp->p_pgrp->pg_id)
-                               pidchecked = rpp->p_pgrp->pg_id;
+                       if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
+                               pidchecked = p2->p_pid;
+                       if (p2->p_pgrp->pg_id > nextpid && 
+                           pidchecked > p2->p_pgrp->pg_id)
+                               pidchecked = p2->p_pgrp->pg_id;

                }
                if (!doingzomb) {
                        doingzomb = 1;
                }
                if (!doingzomb) {
                        doingzomb = 1;

-                       rpp = zombproc;
+                       p2 = zombproc;

                        goto again;
                }
        }
                        goto again;
                }
        }

-       if ((rpp = freeproc) == NULL)
-               panic("no procs");

 
 

-       freeproc = rpp->p_nxt;                  /* off freeproc */
-       rpp->p_nxt = allproc;                   /* onto allproc */
-       rpp->p_nxt->p_prev = &rpp->p_nxt;       /*   (allproc is never NULL) */
-       rpp->p_prev = &allproc;
-       allproc = rpp;
+
+       /*
+        * Allocate new proc.
+        * Link onto allproc (this should probably be delayed).
+        */
+       MALLOC(p2, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK);
+       nprocs++;
+       p2->p_nxt = allproc;
+       p2->p_nxt->p_prev = &p2->p_nxt;         /* allproc is never NULL */
+       p2->p_prev = &allproc;
+       allproc = p2;
+       p2->p_link = NULL;                      /* shouldn't be necessary */
+       p2->p_rlink = NULL;                     /* shouldn't be necessary */

 
        /*
         * Make a proc table entry for the new process.
 
        /*
         * Make a proc table entry for the new process.

+        * Start by zeroing the section of proc that is zero-initialized,
+        * then copy the section that is copied directly from the parent.

         */
         */

-       rip = u.u_procp;
-#if defined(tahoe)
-       rpp->p_ckey = rip->p_ckey;
-       rpp->p_dkey = 0;
-#endif
-       rpp->p_stat = SIDL;
-       timerclear(&rpp->p_realtimer.it_value);
-       rpp->p_flag = SLOAD | (rip->p_flag & (SPAGV|SHPUX));
-       if (rip->p_session->s_ttyvp != NULL && rip->p_flag & SCTTY)
-               rpp->p_flag |= SCTTY;
-       if (isvfork)
-               rpp->p_flag |= SVFORK;
-       rpp->p_ndx = rpp - proc;
-       bcopy(rip->p_comm, rpp->p_comm, MAXCOMLEN+1);
-       bcopy(rip->p_logname, rpp->p_logname, MAXLOGNAME);
-       rpp->p_uid = rip->p_uid;
-       rpp->p_ruid = rip->p_ruid;
-       rpp->p_rgid = rip->p_rgid;
-       rpp->p_pgrp = rip->p_pgrp;
-       rpp->p_pgrpnxt = rip->p_pgrpnxt;
-       rip->p_pgrpnxt = rpp;
-       rpp->p_nice = rip->p_nice;
-       rpp->p_pid = mpid;
-       rpp->p_ppid = rip->p_pid;
-       rpp->p_pptr = rip;
-       rpp->p_osptr = rip->p_cptr;
-       if (rip->p_cptr)
-               rip->p_cptr->p_ysptr = rpp;
-       rpp->p_ysptr = NULL;
-       rpp->p_cptr = NULL;
-       rip->p_cptr = rpp;
-       rpp->p_time = 0;
-       bzero((caddr_t)&rpp->p_utime, sizeof (struct timeval));
-       bzero((caddr_t)&rpp->p_stime, sizeof (struct timeval));
-       rpp->p_cpu = 0;
-       rpp->p_sigmask = rip->p_sigmask;
-       rpp->p_sigcatch = rip->p_sigcatch;
-       rpp->p_sigignore = rip->p_sigignore;
-#ifdef KTRACE
-       if (rip->p_traceflag&KTRFAC_INHERIT) {
-               rpp->p_traceflag = rip->p_traceflag;
-               if ((rpp->p_tracep = rip->p_tracep) != NULL)
-                       VREF(rpp->p_tracep);
-       } else {
-               rpp->p_tracep = NULL;
-               rpp->p_traceflag = 0;
+       bzero(&p2->p_startzero,
+           (unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
+       bcopy(&p1->p_startcopy, &p2->p_startcopy,
+           (unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
+       p2->p_spare[0] = 0;     /* XXX - should be in zero range */
+       p2->p_spare[1] = 0;     /* XXX - should be in zero range */
+       p2->p_spare[2] = 0;     /* XXX - should be in zero range */
+       p2->p_spare[3] = 0;     /* XXX - should be in zero range */
+
+       /*
+        * Duplicate sub-structures as needed.
+        * Increase reference counts on shared objects.
+        * The p_stats and p_sigacts substructs are set in vm_fork.
+        */
+       MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
+           M_SUBPROC, M_WAITOK);
+       bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
+       p2->p_cred->p_refcnt = 1;
+       crhold(p1->p_ucred);
+
+       p2->p_fd = fdcopy(p1);
+       /*
+        * If p_limit is still copy-on-write, bump refcnt,
+        * otherwise get a copy that won't be modified.
+        * (If PL_SHAREMOD is clear, the structure is shared
+        * copy-on-write.)
+        */
+       if (p1->p_limit->p_lflags & PL_SHAREMOD)
+               p2->p_limit = limcopy(p1->p_limit);
+       else {
+               p2->p_limit = p1->p_limit;
+               p2->p_limit->p_refcnt++;

        }
        }

-#endif
-       rpp->p_rssize = 0;
-       rpp->p_maxrss = rip->p_maxrss;
-       rpp->p_wchan = 0;
-       rpp->p_slptime = 0;
-       rpp->p_pctcpu = 0;
-       rpp->p_cpticks = 0;
+
+       p2->p_flag = SLOAD | (p1->p_flag & SHPUX);
+       if (p1->p_session->s_ttyvp != NULL && p1->p_flag & SCTTY)
+               p2->p_flag |= SCTTY;
+       if (isvfork)
+               p2->p_flag |= SPPWAIT;
+       p2->p_stat = SIDL;
+       p2->p_pid = nextpid;

        {
        {

-       struct proc **hash = &pidhash[PIDHASH(rpp->p_pid)];
+       struct proc **hash = &pidhash[PIDHASH(p2->p_pid)];

 
 

-       rpp->p_hash = *hash;
-       *hash = rpp;
+       p2->p_hash = *hash;
+       *hash = p2;

        }
        }

-
+       p2->p_pgrpnxt = p1->p_pgrpnxt;
+       p1->p_pgrpnxt = p2;
+       p2->p_pptr = p1;
+       p2->p_osptr = p1->p_cptr;
+       if (p1->p_cptr)
+               p1->p_cptr->p_ysptr = p2;
+       p1->p_cptr = p2;
+#ifdef KTRACE

        /*
        /*

-        * Increase reference counts on shared objects.
+        * Copy traceflag and tracefile if enabled.
+        * If not inherited, these were zeroed above.

         */
         */

-       for (n = 0; n <= u.u_lastfile; n++) {
-               fp = u.u_ofile[n];
-               if (fp == NULL)
-                       continue;
-               fp->f_count++;
+       if (p1->p_traceflag&KTRFAC_INHERIT) {
+               p2->p_traceflag = p1->p_traceflag;
+               if ((p2->p_tracep = p1->p_tracep) != NULL)
+                       VREF(p2->p_tracep);

        }
        }

-#ifdef SYSVSHM
-       if (rip->p_shm)
-               shmfork(rip, rpp, isvfork);

 #endif
 #endif

-       VREF(u.u_cdir);
-       if (u.u_rdir)
-               VREF(u.u_rdir);
-       crhold(u.u_cred);
+
+#if defined(tahoe)
+       p2->p_vmspace->p_ckey = p1->p_vmspace->p_ckey; /* XXX move this */
+#endif

 
        /*
         * This begins the section where we must prevent the parent
         * from being swapped.
         */
 
        /*
         * This begins the section where we must prevent the parent
         * from being swapped.
         */

-       rip->p_flag |= SKEEP;
-       if (procdup(rpp, isvfork)) {
+       p1->p_flag |= SKEEP;
+       /*
+        * Set return values for child before vm_fork,
+        * so they can be copied to child stack.
+        * We return parent pid, and mark as child in retval[1].
+        * NOTE: the kernel stack may be at a different location in the child
+        * process, and thus addresses of automatic variables (including retval)
+        * may be invalid after vm_fork returns in the child process.
+        */
+       retval[0] = p1->p_pid;
+       retval[1] = 1;
+       if (vm_fork(p1, p2, isvfork)) {
+               /*
+                * Child process.  Set start time and get to work.
+                */

                (void) splclock();
                (void) splclock();

-               u.u_start = time;
+               p2->p_stats->p_start = time;

                (void) spl0();
                (void) spl0();

-               return (1);
+               p2->p_acflag = AFORK;
+               return (0);

        }
 
        /*
         * Make child runnable and add to run queue.
         */
        }
 
        /*
         * Make child runnable and add to run queue.
         */

-       (void) splclock();
-       rpp->p_stat = SRUN;
-       setrq(rpp);
+       (void) splhigh();
+       p2->p_stat = SRUN;
+       setrq(p2);

        (void) spl0();
 
        (void) spl0();
 

-       /*
-        * Cause child to take a non-local goto as soon as it runs.
-        * On older systems this was done with SSWAP bit in proc
-        * table; on VAX we use u.u_pcb.pcb_sswap so don't need
-        * to do rpp->p_flag |= SSWAP.  Actually do nothing here.
-        */
-       /* rpp->p_flag |= SSWAP; */
-

        /*
         * Now can be swapped.
         */
        /*
         * Now can be swapped.
         */

-       rip->p_flag &= ~SKEEP;
+       p1->p_flag &= ~SKEEP;

 
        /*
 
        /*

-        * XXX preserve synchronization semantics of vfork
+        * Preserve synchronization semantics of vfork.
+        * If waiting for child to exec or exit, set SPPWAIT
+        * on child, and sleep on our proc (in case of exit).

         */
         */

-       if (isvfork) {
-               u.u_procp->p_flag |= SNOVM;
-               while (rpp->p_flag & SVFORK)
-                       sleep((caddr_t)rpp, PZERO - 1);
-               if ((rpp->p_flag & SLOAD) == 0)
-                       panic("newproc vfork");
-               u.u_procp->p_flag &= ~SNOVM;
-               rpp->p_flag |= SVFDONE;
-               wakeup((caddr_t)rpp);
-       }
+       if (isvfork)
+               while (p2->p_flag & SPPWAIT)
+                       tsleep((caddr_t)p1, PWAIT, "ppwait", 0);

 
        /*
 
        /*

-        * 0 return means parent.
+        * Return child pid to parent process,
+        * marking us as parent via retval[1].

         */
         */

+       retval[0] = p2->p_pid;
+       retval[1] = 0;

        return (0);
 }
        return (0);
 }