/* * Copyright (c) 1982, 1986, 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 * $FreeBSD: src/sys/kern/kern_exit.c,v 1.92.2.11 2003/01/13 22:51:16 dillon Exp $ */ #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* for acct_process() function prototype */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static void reaplwps(void *context, int dummy); static void reaplwp(struct lwp *lp); static void killlwps(struct lwp *lp); static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback"); /* * callout list for things to do at exit time */ struct exitlist { exitlist_fn function; TAILQ_ENTRY(exitlist) next; }; TAILQ_HEAD(exit_list_head, exitlist); static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list); /* * LWP reaper data */ static struct task *deadlwp_task[MAXCPU]; static struct lwplist deadlwp_list[MAXCPU]; static struct lwkt_token deadlwp_token[MAXCPU]; /* * exit -- * Death of process. * * SYS_EXIT_ARGS(int rval) */ int sys_exit(struct exit_args *uap) { exit1(W_EXITCODE(uap->rval, 0)); /* NOTREACHED */ } /* * Extended exit -- * Death of a lwp or process with optional bells and whistles. */ int sys_extexit(struct extexit_args *uap) { struct proc *p = curproc; int action, who; int error; action = EXTEXIT_ACTION(uap->how); who = EXTEXIT_WHO(uap->how); /* Check parameters before we might perform some action */ switch (who) { case EXTEXIT_PROC: case EXTEXIT_LWP: break; default: return (EINVAL); } switch (action) { case EXTEXIT_SIMPLE: break; case EXTEXIT_SETINT: error = copyout(&uap->status, uap->addr, sizeof(uap->status)); if (error) return (error); break; default: return (EINVAL); } lwkt_gettoken(&p->p_token); switch (who) { case EXTEXIT_LWP: /* * Be sure only to perform a simple lwp exit if there is at * least one more lwp in the proc, which will call exit1() * later, otherwise the proc will be an UNDEAD and not even a * SZOMB! */ if (p->p_nthreads > 1) { lwp_exit(0, NULL); /* called w/ p_token held */ /* NOT REACHED */ } /* else last lwp in proc: do the real thing */ /* FALLTHROUGH */ default: /* to help gcc */ case EXTEXIT_PROC: lwkt_reltoken(&p->p_token); exit1(W_EXITCODE(uap->status, 0)); /* NOTREACHED */ } /* NOTREACHED */ lwkt_reltoken(&p->p_token); /* safety */ } /* * Kill all lwps associated with the current process except the * current lwp. Return an error if we race another thread trying to * do the same thing and lose the race. * * If forexec is non-zero the current thread and process flags are * cleaned up so they can be reused. */ int killalllwps(int forexec) { struct lwp *lp = curthread->td_lwp; struct proc *p = lp->lwp_proc; int fakestop; /* * Interlock against P_WEXIT. Only one of the process's thread * is allowed to do the master exit. */ lwkt_gettoken(&p->p_token); if (p->p_flags & P_WEXIT) { lwkt_reltoken(&p->p_token); return (EALREADY); } p->p_flags |= P_WEXIT; lwkt_gettoken(&lp->lwp_token); /* * Set temporary stopped state in case we are racing a coredump. * Otherwise the coredump may hang forever. */ if (lp->lwp_mpflags & LWP_MP_WSTOP) { fakestop = 0; } else { atomic_set_int(&lp->lwp_mpflags, LWP_MP_WSTOP); ++p->p_nstopped; fakestop = 1; wakeup(&p->p_nstopped); } /* * Interlock with LWP_MP_WEXIT and kill any remaining LWPs */ atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT); if (p->p_nthreads > 1) killlwps(lp); /* * Undo temporary stopped state */ if (fakestop) { atomic_clear_int(&lp->lwp_mpflags, LWP_MP_WSTOP); --p->p_nstopped; } /* * If doing this for an exec, clean up the remaining thread * (us) for continuing operation after all the other threads * have been killed. */ if (forexec) { atomic_clear_int(&lp->lwp_mpflags, LWP_MP_WEXIT); p->p_flags &= ~P_WEXIT; } lwkt_reltoken(&lp->lwp_token); lwkt_reltoken(&p->p_token); return(0); } /* * Kill all LWPs except the current one. Do not try to signal * LWPs which have exited on their own or have already been * signaled. */ static void killlwps(struct lwp *lp) { struct proc *p = lp->lwp_proc; struct lwp *tlp; /* * Kill the remaining LWPs. We must send the signal before setting * LWP_MP_WEXIT. The setting of WEXIT is optional but helps reduce * races. tlp must be held across the call as it might block and * allow the target lwp to rip itself out from under our loop. */ FOREACH_LWP_IN_PROC(tlp, p) { LWPHOLD(tlp); lwkt_gettoken(&tlp->lwp_token); if ((tlp->lwp_mpflags & LWP_MP_WEXIT) == 0) { atomic_set_int(&tlp->lwp_mpflags, LWP_MP_WEXIT); lwpsignal(p, tlp, SIGKILL); } lwkt_reltoken(&tlp->lwp_token); LWPRELE(tlp); } /* * Wait for everything to clear out. Also make sure any tstop()s * are signalled (we are holding p_token for the interlock). */ wakeup(p); while (p->p_nthreads > 1) tsleep(&p->p_nthreads, 0, "killlwps", 0); } /* * Exit: deallocate address space and other resources, change proc state * to zombie, and unlink proc from allproc and parent's lists. Save exit * status and rusage for wait(). Check for child processes and orphan them. */ void exit1(int rv) { struct thread *td = curthread; struct proc *p = td->td_proc; struct lwp *lp = td->td_lwp; struct proc *q; struct proc *pp; struct proc *reproc; struct sysreaper *reap; struct vmspace *vm; struct vnode *vtmp; struct exitlist *ep; int error; lwkt_gettoken(&p->p_token); if (p->p_pid == 1) { kprintf("init died (signal %d, exit %d)\n", WTERMSIG(rv), WEXITSTATUS(rv)); panic("Going nowhere without my init!"); } varsymset_clean(&p->p_varsymset); lockuninit(&p->p_varsymset.vx_lock); /* * Kill all lwps associated with the current process, return an * error if we race another thread trying to do the same thing * and lose the race. */ error = killalllwps(0); if (error) { lwp_exit(0, NULL); /* NOT REACHED */ } /* are we a task leader? */ if (p == p->p_leader) { struct kill_args killArgs; killArgs.signum = SIGKILL; q = p->p_peers; while(q) { killArgs.pid = q->p_pid; /* * The interface for kill is better * than the internal signal */ sys_kill(&killArgs); q = q->p_peers; } while (p->p_peers) tsleep((caddr_t)p, 0, "exit1", 0); } #ifdef PGINPROF vmsizmon(); #endif STOPEVENT(p, S_EXIT, rv); p->p_flags |= P_POSTEXIT; /* stop procfs stepping */ /* * Check if any loadable modules need anything done at process exit. * e.g. SYSV IPC stuff * XXX what if one of these generates an error? */ p->p_xstat = rv; /* * XXX: imho, the eventhandler stuff is much cleaner than this. * Maybe we should move everything to use eventhandler. */ TAILQ_FOREACH(ep, &exit_list, next) (*ep->function)(td); if (p->p_flags & P_PROFIL) stopprofclock(p); SIGEMPTYSET(p->p_siglist); SIGEMPTYSET(lp->lwp_siglist); if (timevalisset(&p->p_realtimer.it_value)) callout_stop_sync(&p->p_ithandle); /* * Reset any sigio structures pointing to us as a result of * F_SETOWN with our pid. */ funsetownlst(&p->p_sigiolst); /* * Close open files and release open-file table. * This may block! */ fdfree(p, NULL); if (p->p_leader->p_peers) { q = p->p_leader; while(q->p_peers != p) q = q->p_peers; q->p_peers = p->p_peers; wakeup((caddr_t)p->p_leader); } /* * XXX Shutdown SYSV semaphores */ semexit(p); /* The next two chunks should probably be moved to vmspace_exit. */ vm = p->p_vmspace; /* * Clean up data related to virtual kernel operation. Clean up * any vkernel context related to the current lwp now so we can * destroy p_vkernel. */ if (p->p_vkernel) { vkernel_lwp_exit(lp); vkernel_exit(p); } /* * Release the user portion of address space. The exitbump prevents * the vmspace from being completely eradicated (using holdcnt). * This releases references to vnodes, which could cause I/O if the * file has been unlinked. We need to do this early enough that * we can still sleep. * * We can't free the entire vmspace as the kernel stack may be mapped * within that space also. * * Processes sharing the same vmspace may exit in one order, and * get cleaned up by vmspace_exit() in a different order. The * last exiting process to reach this point releases as much of * the environment as it can, and the last process cleaned up * by vmspace_exit() (which decrements exitingcnt) cleans up the * remainder. * * NOTE: Releasing p_token around this call is helpful if the * vmspace had a huge RSS. Otherwise some other process * trying to do an allproc or other scan (like 'ps') may * stall for a long time. */ lwkt_reltoken(&p->p_token); vmspace_relexit(vm); lwkt_gettoken(&p->p_token); if (SESS_LEADER(p)) { struct session *sp = p->p_session; if (sp->s_ttyvp) { /* * We are the controlling process. Signal the * foreground process group, drain the controlling * terminal, and revoke access to the controlling * terminal. * * NOTE: while waiting for the process group to exit * it is possible that one of the processes in the * group will revoke the tty, so the ttyclosesession() * function will re-check sp->s_ttyvp. */ if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) { if (sp->s_ttyp->t_pgrp) pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); ttywait(sp->s_ttyp); ttyclosesession(sp, 1); /* also revoke */ } /* * Release the tty. If someone has it open via * /dev/tty then close it (since they no longer can * once we've NULL'd it out). */ ttyclosesession(sp, 0); /* * s_ttyp is not zero'd; we use this to indicate * that the session once had a controlling terminal. * (for logging and informational purposes) */ } sp->s_leader = NULL; } fixjobc(p, p->p_pgrp, 0); (void)acct_process(p); #ifdef KTRACE /* * release trace file */ if (p->p_tracenode) ktrdestroy(&p->p_tracenode); p->p_traceflag = 0; #endif /* * Release reference to text vnode */ if ((vtmp = p->p_textvp) != NULL) { p->p_textvp = NULL; vrele(vtmp); } /* Release namecache handle to text file */ if (p->p_textnch.ncp) cache_drop(&p->p_textnch); /* * We have to handle PPWAIT here or proc_move_allproc_zombie() * will block on the PHOLD() the parent is doing. * * We are using the flag as an interlock so an atomic op is * necessary to synchronize with the parent's cpu. */ if (p->p_flags & P_PPWAIT) { if (p->p_pptr && p->p_pptr->p_upmap) atomic_add_int(&p->p_pptr->p_upmap->invfork, -1); atomic_clear_int(&p->p_flags, P_PPWAIT); wakeup(p->p_pptr); } /* * Move the process to the zombie list. This will block * until the process p_lock count reaches 0. The process will * not be reaped until TDF_EXITING is set by cpu_thread_exit(), * which is called from cpu_proc_exit(). * * Interlock against waiters using p_waitgen. We increment * p_waitgen after completing the move of our process to the * zombie list. * * WARNING: pp becomes stale when we block, clear it now as a * reminder. */ proc_move_allproc_zombie(p); pp = p->p_pptr; atomic_add_long(&pp->p_waitgen, 1); pp = NULL; /* * release controlled reaper for exit if we own it and return the * remaining reaper (the one for us), which we will drop after we * are done. */ reap = reaper_exit(p); /* * Reparent all of this process's children to the init process or * to the designated reaper. We must hold the reaper's p_token in * order to safely mess with p_children. * * We already hold p->p_token (to remove the children from our list). */ reproc = NULL; q = LIST_FIRST(&p->p_children); if (q) { reproc = reaper_get(reap); lwkt_gettoken(&reproc->p_token); while ((q = LIST_FIRST(&p->p_children)) != NULL) { PHOLD(q); lwkt_gettoken(&q->p_token); if (q != LIST_FIRST(&p->p_children)) { lwkt_reltoken(&q->p_token); PRELE(q); continue; } LIST_REMOVE(q, p_sibling); LIST_INSERT_HEAD(&reproc->p_children, q, p_sibling); q->p_pptr = reproc; q->p_ppid = reproc->p_pid; q->p_sigparent = SIGCHLD; /* * Traced processes are killed * since their existence means someone is screwing up. */ if (q->p_flags & P_TRACED) { q->p_flags &= ~P_TRACED; ksignal(q, SIGKILL); } lwkt_reltoken(&q->p_token); PRELE(q); } lwkt_reltoken(&reproc->p_token); wakeup(reproc); } /* * Save exit status and final rusage info. We no longer add * child rusage info into self times, wait4() and kern_wait() * handles it in order to properly support wait6(). */ calcru_proc(p, &p->p_ru); /*ruadd(&p->p_ru, &p->p_cru); REMOVED */ /* * notify interested parties of our demise. */ KNOTE(&p->p_klist, NOTE_EXIT); /* * Notify parent that we're gone. If parent has the PS_NOCLDWAIT * flag set, or if the handler is set to SIG_IGN, notify the reaper * instead (it will handle this situation). * * NOTE: The reaper can still be the parent process. * * (must reload pp) */ if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) { if (reproc == NULL) reproc = reaper_get(reap); proc_reparent(p, reproc); } if (reproc) PRELE(reproc); if (reap) reaper_drop(reap); /* * Signal (possibly new) parent. */ pp = p->p_pptr; PHOLD(pp); if (p->p_sigparent && pp != initproc) { int sig = p->p_sigparent; if (sig != SIGUSR1 && sig != SIGCHLD) sig = SIGCHLD; ksignal(pp, sig); } else { ksignal(pp, SIGCHLD); } p->p_flags &= ~P_TRACED; PRELE(pp); /* * cpu_exit is responsible for clearing curproc, since * it is heavily integrated with the thread/switching sequence. * * Other substructures are freed from wait(). */ if (p->p_limit) { struct plimit *rlimit; rlimit = p->p_limit; p->p_limit = NULL; plimit_free(rlimit); } /* * Finally, call machine-dependent code to release as many of the * lwp's resources as we can and halt execution of this thread. * * pp is a wild pointer now but still the correct wakeup() target. * lwp_exit() only uses it to send the wakeup() signal to the likely * parent. Any reparenting race that occurs will get a signal * automatically and not be an issue. */ lwp_exit(1, pp); } /* * Eventually called by every exiting LWP * * p->p_token must be held. mplock may be held and will be released. */ void lwp_exit(int masterexit, void *waddr) { struct thread *td = curthread; struct lwp *lp = td->td_lwp; struct proc *p = lp->lwp_proc; int dowake = 0; /* * Release the current user process designation on the process so * the userland scheduler can work in someone else. */ p->p_usched->release_curproc(lp); /* * lwp_exit() may be called without setting LWP_MP_WEXIT, so * make sure it is set here. */ ASSERT_LWKT_TOKEN_HELD(&p->p_token); atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT); /* * Clean up any virtualization */ if (lp->lwp_vkernel) vkernel_lwp_exit(lp); if (td->td_vmm) vmm_vmdestroy(); /* * Clean up select/poll support */ kqueue_terminate(&lp->lwp_kqueue); /* * Clean up any syscall-cached ucred or rlimit. */ if (td->td_ucred) { crfree(td->td_ucred); td->td_ucred = NULL; } if (td->td_limit) { struct plimit *rlimit; rlimit = td->td_limit; td->td_limit = NULL; plimit_free(rlimit); } /* * Cleanup any cached descriptors for this thread */ if (p->p_fd) fexitcache(td); /* * Nobody actually wakes us when the lock * count reaches zero, so just wait one tick. */ while (lp->lwp_lock > 0) tsleep(lp, 0, "lwpexit", 1); /* Hand down resource usage to our proc */ ruadd(&p->p_ru, &lp->lwp_ru); /* * If we don't hold the process until the LWP is reaped wait*() * may try to dispose of its vmspace before all the LWPs have * actually terminated. */ PHOLD(p); /* * Do any remaining work that might block on us. We should be * coded such that further blocking is ok after decrementing * p_nthreads but don't take the chance. */ dsched_exit_thread(td); biosched_done(curthread); /* * We have to use the reaper for all the LWPs except the one doing * the master exit. The LWP doing the master exit can just be * left on p_lwps and the process reaper will deal with it * synchronously, which is much faster. * * Wakeup anyone waiting on p_nthreads to drop to 1 or 0. * * The process is left held until the reaper calls lwp_dispose() on * the lp (after calling lwp_wait()). */ if (masterexit == 0) { int cpu = mycpuid; lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); --p->p_nthreads; if ((p->p_flags & P_MAYBETHREADED) && p->p_nthreads <= 1) dowake = 1; lwkt_gettoken(&deadlwp_token[cpu]); LIST_INSERT_HEAD(&deadlwp_list[cpu], lp, u.lwp_reap_entry); taskqueue_enqueue(taskqueue_thread[cpu], deadlwp_task[cpu]); lwkt_reltoken(&deadlwp_token[cpu]); } else { --p->p_nthreads; if ((p->p_flags & P_MAYBETHREADED) && p->p_nthreads <= 1) dowake = 1; } /* * We no longer need p_token. * * Tell the userland scheduler that we are going away */ lwkt_reltoken(&p->p_token); p->p_usched->heuristic_exiting(lp, p); /* * Issue late wakeups after releasing our token to give us a chance * to deschedule and switch away before another cpu in a wait*() * reaps us. This is done as late as possible to reduce contention. */ if (dowake) wakeup(&p->p_nthreads); if (waddr) wakeup(waddr); cpu_lwp_exit(); } /* * Wait until a lwp is completely dead. The final interlock in this drama * is when TDF_EXITING is set in cpu_thread_exit() just before the final * switchout. * * At the point TDF_EXITING is set a complete exit is accomplished when * TDF_RUNNING and TDF_PREEMPT_LOCK are both clear. td_mpflags has two * post-switch interlock flags that can be used to wait for the TDF_ * flags to clear. * * Returns non-zero on success, and zero if the caller needs to retry * the lwp_wait(). */ static int lwp_wait(struct lwp *lp) { struct thread *td = lp->lwp_thread; u_int mpflags; KKASSERT(lwkt_preempted_proc() != lp); /* * This bit of code uses the thread destruction interlock * managed by lwkt_switch_return() to wait for the lwp's * thread to completely disengage. * * It is possible for us to race another cpu core so we * have to do this correctly. */ for (;;) { mpflags = td->td_mpflags; cpu_ccfence(); if (mpflags & TDF_MP_EXITSIG) break; tsleep_interlock(td, 0); if (atomic_cmpset_int(&td->td_mpflags, mpflags, mpflags | TDF_MP_EXITWAIT)) { tsleep(td, PINTERLOCKED, "lwpxt", 0); } } /* * We've already waited for the core exit but there can still * be other refs from e.g. process scans and such. */ if (lp->lwp_lock > 0) { tsleep(lp, 0, "lwpwait1", 1); return(0); } if (td->td_refs) { tsleep(td, 0, "lwpwait2", 1); return(0); } /* * Now that we have the thread destruction interlock these flags * really should already be cleaned up, keep a check for safety. * * We can't rip its stack out from under it until TDF_EXITING is * set and both TDF_RUNNING and TDF_PREEMPT_LOCK are clear. * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING * will be cleared temporarily if a thread gets preempted. */ while ((td->td_flags & (TDF_RUNNING | TDF_RUNQ | TDF_PREEMPT_LOCK | TDF_EXITING)) != TDF_EXITING) { tsleep(lp, 0, "lwpwait3", 1); return (0); } KASSERT((td->td_flags & (TDF_RUNQ|TDF_TSLEEPQ)) == 0, ("lwp_wait: td %p (%s) still on run or sleep queue", td, td->td_comm)); return (1); } /* * Release the resources associated with a lwp. * The lwp must be completely dead. */ void lwp_dispose(struct lwp *lp) { struct thread *td = lp->lwp_thread; KKASSERT(lwkt_preempted_proc() != lp); KKASSERT(lp->lwp_lock == 0); KKASSERT(td->td_refs == 0); KKASSERT((td->td_flags & (TDF_RUNNING | TDF_RUNQ | TDF_PREEMPT_LOCK | TDF_EXITING)) == TDF_EXITING); PRELE(lp->lwp_proc); lp->lwp_proc = NULL; if (td != NULL) { td->td_proc = NULL; td->td_lwp = NULL; lp->lwp_thread = NULL; lwkt_free_thread(td); } kfree(lp, M_LWP); } int sys_wait4(struct wait_args *uap) { struct __wrusage wrusage; int error; int status; int options; id_t id; idtype_t idtype; options = uap->options | WEXITED | WTRAPPED; id = uap->pid; if (id == WAIT_ANY) { idtype = P_ALL; } else if (id == WAIT_MYPGRP) { idtype = P_PGID; id = curproc->p_pgid; } else if (id < 0) { idtype = P_PGID; id = -id; } else { idtype = P_PID; } error = kern_wait(idtype, id, &status, options, &wrusage, NULL, &uap->sysmsg_result); if (error == 0 && uap->status) error = copyout(&status, uap->status, sizeof(*uap->status)); if (error == 0 && uap->rusage) { ruadd(&wrusage.wru_self, &wrusage.wru_children); error = copyout(&wrusage.wru_self, uap->rusage, sizeof(*uap->rusage)); } return (error); } int sys_wait6(struct wait6_args *uap) { struct __wrusage wrusage; struct __siginfo info; struct __siginfo *infop; int error; int status; int options; id_t id; idtype_t idtype; /* * NOTE: wait6() requires WEXITED and WTRAPPED to be specified if * desired. */ options = uap->options; idtype = uap->idtype; id = uap->id; infop = uap->info ? &info : NULL; switch(idtype) { case P_PID: case P_PGID: if (id == WAIT_MYPGRP) { idtype = P_PGID; id = curproc->p_pgid; } break; default: /* let kern_wait deal with the remainder */ break; } error = kern_wait(idtype, id, &status, options, &wrusage, infop, &uap->sysmsg_result); if (error == 0 && uap->status) error = copyout(&status, uap->status, sizeof(*uap->status)); if (error == 0 && uap->wrusage) error = copyout(&wrusage, uap->wrusage, sizeof(*uap->wrusage)); if (error == 0 && uap->info) error = copyout(&info, uap->info, sizeof(*uap->info)); return (error); } /* * kernel wait*() system call support */ int kern_wait(idtype_t idtype, id_t id, int *status, int options, struct __wrusage *wrusage, struct __siginfo *info, int *res) { struct thread *td = curthread; struct lwp *lp; struct proc *q = td->td_proc; struct proc *p, *t; struct ucred *cr; struct pargs *pa; struct sigacts *ps; int nfound, error; long waitgen; /* * Must not have extraneous options. Must have at least one * matchable option. */ if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE|WSTOPPED| WEXITED|WTRAPPED|WNOWAIT)) { return (EINVAL); } if ((options & (WEXITED | WUNTRACED | WCONTINUED | WTRAPPED)) == 0) { return (EINVAL); } /* * Protect the q->p_children list */ lwkt_gettoken(&q->p_token); loop: /* * All sorts of things can change due to blocking so we have to loop * all the way back up here. * * The problem is that if a process group is stopped and the parent * is doing a wait*(..., WUNTRACED, ...), it will see the STOP * of the child and then stop itself when it tries to return from the * system call. When the process group is resumed the parent will * then get the STOP status even though the child has now resumed * (a followup wait*() will get the CONT status). * * Previously the CONT would overwrite the STOP because the tstop * was handled within tsleep(), and the parent would only see * the CONT when both are stopped and continued together. This little * two-line hack restores this effect. */ if (STOPLWP(q, td->td_lwp)) tstop(); nfound = 0; /* * Loop on children. * * NOTE: We don't want to break q's p_token in the loop for the * case where no children are found or we risk breaking the * interlock between child and parent. */ waitgen = atomic_fetchadd_long(&q->p_waitgen, 0x80000000); LIST_FOREACH(p, &q->p_children, p_sibling) { /* * Filter, (p) will be held on fall-through. Try to optimize * this to avoid the atomic op until we are pretty sure we * want this process. */ switch(idtype) { case P_ALL: PHOLD(p); break; case P_PID: if (p->p_pid != (pid_t)id) continue; PHOLD(p); break; case P_PGID: if (p->p_pgid != (pid_t)id) continue; PHOLD(p); break; case P_SID: PHOLD(p); if (p->p_session && p->p_session->s_sid != (pid_t)id) { PRELE(p); continue; } break; case P_UID: PHOLD(p); if (p->p_ucred->cr_uid != (uid_t)id) { PRELE(p); continue; } break; case P_GID: PHOLD(p); if (p->p_ucred->cr_gid != (gid_t)id) { PRELE(p); continue; } break; case P_JAILID: PHOLD(p); if (p->p_ucred->cr_prison && p->p_ucred->cr_prison->pr_id != (int)id) { PRELE(p); continue; } break; default: /* unsupported filter */ continue; } /* (p) is held at this point */ /* * This special case handles a kthread spawned by linux_clone * (see linux_misc.c). The linux_wait4 and linux_waitpid * functions need to be able to distinguish between waiting * on a process and waiting on a thread. It is a thread if * p_sigparent is not SIGCHLD, and the WLINUXCLONE option * signifies we want to wait for threads and not processes. */ if ((p->p_sigparent != SIGCHLD) ^ ((options & WLINUXCLONE) != 0)) { PRELE(p); continue; } nfound++; if (p->p_stat == SZOMB && (options & WEXITED)) { /* * We may go into SZOMB with threads still present. * We must wait for them to exit before we can reap * the master thread, otherwise we may race reaping * non-master threads. * * Only this routine can remove a process from * the zombie list and destroy it. */ if (PHOLDZOMB(p)) { PRELE(p); goto loop; } lwkt_gettoken(&p->p_token); if (p->p_pptr != q) { lwkt_reltoken(&p->p_token); PRELE(p); PRELEZOMB(p); goto loop; } while (p->p_nthreads > 0) { tsleep(&p->p_nthreads, 0, "lwpzomb", hz); } /* * Reap any LWPs left in p->p_lwps. This is usually * just the last LWP. This must be done before * we loop on p_lock since the lwps hold a ref on * it as a vmspace interlock. * * Once that is accomplished p_nthreads had better * be zero. */ while ((lp = RB_ROOT(&p->p_lwp_tree)) != NULL) { /* * Make sure no one is using this lwp, before * it is removed from the tree. If we didn't * wait it here, lwp tree iteration with * blocking operation would be broken. */ while (lp->lwp_lock > 0) tsleep(lp, 0, "zomblwp", 1); lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); reaplwp(lp); } KKASSERT(p->p_nthreads == 0); /* * Don't do anything really bad until all references * to the process go away. This may include other * LWPs which are still in the process of being * reaped. We can't just pull the rug out from under * them because they may still be using the VM space. * * Certain kernel facilities such as /proc will also * put a hold on the process for short periods of * time. */ PRELE(p); /* from top of loop */ PSTALL(p, "reap3", 1); /* 1 ref (for PZOMBHOLD) */ /* Take care of our return values. */ *res = p->p_pid; *status = p->p_xstat; wrusage->wru_self = p->p_ru; wrusage->wru_children = p->p_cru; if (info) { bzero(info, sizeof(*info)); info->si_errno = 0; info->si_signo = SIGCHLD; if (p->p_xstat) info->si_code = CLD_KILLED; else info->si_code = CLD_EXITED; info->si_status = p->p_xstat; info->si_pid = p->p_pid; info->si_uid = p->p_ucred->cr_uid; } /* * WNOWAIT shortcuts to done here, leaving the * child on the zombie list. */ if (options & WNOWAIT) { lwkt_reltoken(&p->p_token); PRELEZOMB(p); error = 0; goto done; } /* * If we got the child via a ptrace 'attach', * we need to give it back to the old parent. */ if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) { p->p_oppid = 0; proc_reparent(p, t); ksignal(t, SIGCHLD); wakeup((caddr_t)t); PRELE(t); lwkt_reltoken(&p->p_token); PRELEZOMB(p); error = 0; goto done; } /* * Unlink the proc from its process group so that * the following operations won't lead to an * inconsistent state for processes running down * the zombie list. */ proc_remove_zombie(p); proc_userunmap(p); lwkt_reltoken(&p->p_token); leavepgrp(p); p->p_xstat = 0; ruadd(&q->p_cru, &p->p_ru); ruadd(&q->p_cru, &p->p_cru); /* * Decrement the count of procs running with this uid. */ chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0); /* * Free up credentials. p_spin is required to * avoid races against allproc scans. */ spin_lock(&p->p_spin); cr = p->p_ucred; p->p_ucred = NULL; spin_unlock(&p->p_spin); crfree(cr); /* * Remove unused arguments */ pa = p->p_args; p->p_args = NULL; if (pa && refcount_release(&pa->ar_ref)) { kfree(pa, M_PARGS); pa = NULL; } ps = p->p_sigacts; p->p_sigacts = NULL; if (ps && refcount_release(&ps->ps_refcnt)) { kfree(ps, M_SUBPROC); ps = NULL; } /* * Our exitingcount was incremented when the process * became a zombie, now that the process has been * removed from (almost) all lists we should be able * to safely destroy its vmspace. Wait for any current * holders to go away (so the vmspace remains stable), * then scrap it. * * NOTE: Releasing the parent process (q) p_token * across the vmspace_exitfree() call is * important here to reduce stalls on * interactions with (q) (such as * fork/exec/wait or 'ps'). */ PSTALL(p, "reap4", 1); lwkt_reltoken(&q->p_token); vmspace_exitfree(p); lwkt_gettoken(&q->p_token); PSTALL(p, "reap5", 1); /* * NOTE: We have to officially release ZOMB in order * to ensure that a racing thread in kern_wait() * which blocked on ZOMB is woken up. */ PRELEZOMB(p); kfree(p->p_uidpcpu, M_SUBPROC); kfree(p, M_PROC); atomic_add_int(&nprocs, -1); error = 0; goto done; } /* * Process has not yet exited */ if ((p->p_stat == SSTOP || p->p_stat == SCORE) && (p->p_flags & P_WAITED) == 0 && (((p->p_flags & P_TRACED) && (options & WTRAPPED)) || (options & WSTOPPED))) { lwkt_gettoken(&p->p_token); if (p->p_pptr != q) { lwkt_reltoken(&p->p_token); PRELE(p); goto loop; } if ((p->p_stat != SSTOP && p->p_stat != SCORE) || (p->p_flags & P_WAITED) != 0 || ((p->p_flags & P_TRACED) == 0 && (options & WUNTRACED) == 0)) { lwkt_reltoken(&p->p_token); PRELE(p); goto loop; } /* * Don't set P_WAITED if WNOWAIT specified, leaving * the process in a waitable state. */ if ((options & WNOWAIT) == 0) p->p_flags |= P_WAITED; *res = p->p_pid; *status = W_STOPCODE(p->p_xstat); /* Zero rusage so we get something consistent. */ bzero(wrusage, sizeof(*wrusage)); error = 0; if (info) { bzero(info, sizeof(*info)); if (p->p_flags & P_TRACED) info->si_code = CLD_TRAPPED; else info->si_code = CLD_STOPPED; info->si_status = p->p_xstat; } lwkt_reltoken(&p->p_token); PRELE(p); goto done; } if ((options & WCONTINUED) && (p->p_flags & P_CONTINUED)) { lwkt_gettoken(&p->p_token); if (p->p_pptr != q) { lwkt_reltoken(&p->p_token); PRELE(p); goto loop; } if ((p->p_flags & P_CONTINUED) == 0) { lwkt_reltoken(&p->p_token); PRELE(p); goto loop; } *res = p->p_pid; /* * Don't set P_WAITED if WNOWAIT specified, leaving * the process in a waitable state. */ if ((options & WNOWAIT) == 0) p->p_flags &= ~P_CONTINUED; *status = SIGCONT; error = 0; if (info) { bzero(info, sizeof(*info)); info->si_code = CLD_CONTINUED; info->si_status = p->p_xstat; } lwkt_reltoken(&p->p_token); PRELE(p); goto done; } PRELE(p); } if (nfound == 0) { error = ECHILD; goto done; } if (options & WNOHANG) { *res = 0; error = 0; goto done; } /* * Wait for signal - interlocked using q->p_waitgen. */ error = 0; while ((waitgen & 0x7FFFFFFF) == (q->p_waitgen & 0x7FFFFFFF)) { tsleep_interlock(q, PCATCH); waitgen = atomic_fetchadd_long(&q->p_waitgen, 0x80000000); if ((waitgen & 0x7FFFFFFF) == (q->p_waitgen & 0x7FFFFFFF)) { error = tsleep(q, PCATCH | PINTERLOCKED, "wait", 0); break; } } if (error) { done: lwkt_reltoken(&q->p_token); return (error); } goto loop; } /* * Change child's parent process to parent. * * p_children/p_sibling requires the parent's token, and * changing pptr requires the child's token, so we have to * get three tokens to do this operation. We also need to * hold pointers that might get ripped out from under us to * preserve structural integrity. * * It is possible to race another reparent or disconnect or other * similar operation. We must retry when this situation occurs. * Once we successfully reparent the process we no longer care * about any races. */ void proc_reparent(struct proc *child, struct proc *parent) { struct proc *opp; PHOLD(parent); while ((opp = child->p_pptr) != parent) { PHOLD(opp); lwkt_gettoken(&opp->p_token); lwkt_gettoken(&child->p_token); lwkt_gettoken(&parent->p_token); if (child->p_pptr != opp) { lwkt_reltoken(&parent->p_token); lwkt_reltoken(&child->p_token); lwkt_reltoken(&opp->p_token); PRELE(opp); continue; } LIST_REMOVE(child, p_sibling); LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); child->p_pptr = parent; child->p_ppid = parent->p_pid; lwkt_reltoken(&parent->p_token); lwkt_reltoken(&child->p_token); lwkt_reltoken(&opp->p_token); if (LIST_EMPTY(&opp->p_children)) wakeup(opp); PRELE(opp); break; } PRELE(parent); } /* * The next two functions are to handle adding/deleting items on the * exit callout list * * at_exit(): * Take the arguments given and put them onto the exit callout list, * However first make sure that it's not already there. * returns 0 on success. */ int at_exit(exitlist_fn function) { struct exitlist *ep; #ifdef INVARIANTS /* Be noisy if the programmer has lost track of things */ if (rm_at_exit(function)) kprintf("WARNING: exit callout entry (%p) already present\n", function); #endif ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT); if (ep == NULL) return (ENOMEM); ep->function = function; TAILQ_INSERT_TAIL(&exit_list, ep, next); return (0); } /* * Scan the exit callout list for the given item and remove it. * Returns the number of items removed (0 or 1) */ int rm_at_exit(exitlist_fn function) { struct exitlist *ep; TAILQ_FOREACH(ep, &exit_list, next) { if (ep->function == function) { TAILQ_REMOVE(&exit_list, ep, next); kfree(ep, M_ATEXIT); return(1); } } return (0); } /* * LWP reaper related code. */ static void reaplwps(void *context, int dummy) { struct lwplist *lwplist = context; struct lwp *lp; int cpu = mycpuid; lwkt_gettoken(&deadlwp_token[cpu]); while ((lp = LIST_FIRST(lwplist))) { LIST_REMOVE(lp, u.lwp_reap_entry); reaplwp(lp); } lwkt_reltoken(&deadlwp_token[cpu]); } static void reaplwp(struct lwp *lp) { while (lwp_wait(lp) == 0) ; lwp_dispose(lp); } static void deadlwp_init(void) { int cpu; for (cpu = 0; cpu < ncpus; cpu++) { lwkt_token_init(&deadlwp_token[cpu], "deadlwpl"); LIST_INIT(&deadlwp_list[cpu]); deadlwp_task[cpu] = kmalloc(sizeof(*deadlwp_task[cpu]), M_DEVBUF, M_WAITOK); TASK_INIT(deadlwp_task[cpu], 0, reaplwps, &deadlwp_list[cpu]); } } SYSINIT(deadlwpinit, SI_SUB_CONFIGURE, SI_ORDER_ANY, deadlwp_init, NULL);