/* * 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_fork.c 8.6 (Berkeley) 4/8/94 * $FreeBSD: src/sys/kern/kern_fork.c,v 1.72.2.14 2003/06/26 04:15:10 silby Exp $ */ #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static MALLOC_DEFINE(M_ATFORK, "atfork", "atfork callback"); static MALLOC_DEFINE(M_REAPER, "reaper", "process reapers"); /* * These are the stuctures used to create a callout list for things to do * when forking a process */ struct forklist { forklist_fn function; TAILQ_ENTRY(forklist) next; }; TAILQ_HEAD(forklist_head, forklist); static struct forklist_head fork_list = TAILQ_HEAD_INITIALIZER(fork_list); static struct lwp *lwp_fork1(struct lwp *, struct proc *, int flags, const cpumask_t *mask); static void lwp_fork2(struct lwp *lp1, struct proc *destproc, struct lwp *lp2, int flags); static int lwp_create1(struct lwp_params *params, const cpumask_t *mask); static struct lock reaper_lock = LOCK_INITIALIZER("reapgl", 0, 0); int forksleep; /* Place for fork1() to sleep on. */ /* * Red-Black tree support for LWPs */ static int rb_lwp_compare(struct lwp *lp1, struct lwp *lp2) { if (lp1->lwp_tid < lp2->lwp_tid) return(-1); if (lp1->lwp_tid > lp2->lwp_tid) return(1); return(0); } RB_GENERATE2(lwp_rb_tree, lwp, u.lwp_rbnode, rb_lwp_compare, lwpid_t, lwp_tid); /* * When forking, memory underpinning umtx-supported mutexes may be set * COW causing the physical address to change. We must wakeup any threads * blocked on the physical address to allow them to re-resolve their VM. * * (caller is holding p->p_token) */ static void wake_umtx_threads(struct proc *p1) { struct lwp *lp; struct thread *td; RB_FOREACH(lp, lwp_rb_tree, &p1->p_lwp_tree) { td = lp->lwp_thread; if (td && (td->td_flags & TDF_TSLEEPQ) && (td->td_wdomain & PDOMAIN_MASK) == PDOMAIN_UMTX) { wakeup_domain(td->td_wchan, PDOMAIN_UMTX); } } } /* * fork() system call */ int sys_fork(struct sysmsg *sysmsg, const struct fork_args *uap) { struct lwp *lp = curthread->td_lwp; struct proc *p2; int error; error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2); if (error == 0) { PHOLD(p2); start_forked_proc(lp, p2); sysmsg->sysmsg_fds[0] = p2->p_pid; sysmsg->sysmsg_fds[1] = 0; PRELE(p2); } return error; } /* * vfork() system call */ int sys_vfork(struct sysmsg *sysmsg, const struct vfork_args *uap) { struct lwp *lp = curthread->td_lwp; struct proc *p2; int error; error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2); if (error == 0) { PHOLD(p2); start_forked_proc(lp, p2); sysmsg->sysmsg_fds[0] = p2->p_pid; sysmsg->sysmsg_fds[1] = 0; PRELE(p2); } return error; } /* * Handle rforks. An rfork may (1) operate on the current process without * creating a new, (2) create a new process that shared the current process's * vmspace, signals, and/or descriptors, or (3) create a new process that does * not share these things (normal fork). * * Note that we only call start_forked_proc() if a new process is actually * created. * * rfork { int flags } */ int sys_rfork(struct sysmsg *sysmsg, const struct rfork_args *uap) { struct lwp *lp = curthread->td_lwp; struct proc *p2; int error; if ((uap->flags & RFKERNELONLY) != 0) return (EINVAL); error = fork1(lp, uap->flags | RFPGLOCK, &p2); if (error == 0) { if (p2) { PHOLD(p2); start_forked_proc(lp, p2); sysmsg->sysmsg_fds[0] = p2->p_pid; sysmsg->sysmsg_fds[1] = 0; PRELE(p2); } else { sysmsg->sysmsg_fds[0] = 0; sysmsg->sysmsg_fds[1] = 0; } } return error; } static int lwp_create1(struct lwp_params *uprm, const cpumask_t *umask) { struct proc *p = curproc; struct lwp *lp; struct lwp_params params; cpumask_t *mask = NULL, mask0; int error; error = copyin(uprm, ¶ms, sizeof(params)); if (error) goto fail2; if (umask != NULL) { error = copyin(umask, &mask0, sizeof(mask0)); if (error) goto fail2; CPUMASK_ANDMASK(mask0, smp_active_mask); if (CPUMASK_TESTNZERO(mask0)) mask = &mask0; } lwkt_gettoken(&p->p_token); plimit_lwp_fork(p); /* force exclusive access */ lp = lwp_fork1(curthread->td_lwp, p, RFPROC | RFMEM, mask); lwp_fork2(curthread->td_lwp, p, lp, RFPROC | RFMEM); error = cpu_prepare_lwp(lp, ¶ms); if (error) goto fail; if (params.lwp_tid1 != NULL && (error = copyout(&lp->lwp_tid, params.lwp_tid1, sizeof(lp->lwp_tid)))) goto fail; if (params.lwp_tid2 != NULL && (error = copyout(&lp->lwp_tid, params.lwp_tid2, sizeof(lp->lwp_tid)))) goto fail; /* * Now schedule the new lwp. */ p->p_usched->resetpriority(lp); crit_enter(); lp->lwp_stat = LSRUN; p->p_usched->setrunqueue(lp); crit_exit(); lwkt_reltoken(&p->p_token); return (0); fail: /* * 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, "lwpfail", 1); lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); --p->p_nthreads; /* lwp_dispose expects an exited lwp, and a held proc */ atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT); lp->lwp_thread->td_flags |= TDF_EXITING; lwkt_remove_tdallq(lp->lwp_thread); PHOLD(p); biosched_done(lp->lwp_thread); dsched_exit_thread(lp->lwp_thread); lwp_dispose(lp); lwkt_reltoken(&p->p_token); fail2: return (error); } /* * Low level thread create used by pthreads. */ int sys_lwp_create(struct sysmsg *sysmsg, const struct lwp_create_args *uap) { return (lwp_create1(uap->params, NULL)); } int sys_lwp_create2(struct sysmsg *sysmsg, const struct lwp_create2_args *uap) { return (lwp_create1(uap->params, uap->mask)); } int nprocs = 1; /* process 0 */ int fork1(struct lwp *lp1, int flags, struct proc **procp) { struct proc *p1 = lp1->lwp_proc; struct proc *p2; struct proc *pptr; struct pgrp *p1grp; struct pgrp *plkgrp; struct lwp *lp2; struct sysreaper *reap; uid_t uid; int ok, error; static int curfail = 0; static struct timeval lastfail; struct forklist *ep; struct filedesc_to_leader *fdtol; if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG)) return (EINVAL); lwkt_gettoken(&p1->p_token); plkgrp = NULL; p2 = NULL; /* * Here we don't create a new process, but we divorce * certain parts of a process from itself. */ if ((flags & RFPROC) == 0) { /* * This kind of stunt does not work anymore if * there are native threads (lwps) running */ if (p1->p_nthreads != 1) { error = EINVAL; goto done; } vm_fork(p1, NULL, NULL, flags); if ((flags & RFMEM) == 0) wake_umtx_threads(p1); /* * Close all file descriptors. */ if (flags & RFCFDG) { struct filedesc *fdtmp; fdtmp = fdinit(p1); fdfree(p1, fdtmp); } /* * Unshare file descriptors (from parent.) */ if (flags & RFFDG) { if (p1->p_fd->fd_refcnt > 1) { struct filedesc *newfd; error = fdcopy(p1, &newfd); if (error != 0) { error = ENOMEM; goto done; } fdfree(p1, newfd); } } *procp = NULL; error = 0; goto done; } /* * Interlock against process group signal delivery. If signals * are pending after the interlock is obtained we have to restart * the system call to process the signals. If we don't the child * can miss a pgsignal (such as ^C) sent during the fork. * * We can't use CURSIG() here because it will process any STOPs * and cause the process group lock to be held indefinitely. If * a STOP occurs, the fork will be restarted after the CONT. */ p1grp = p1->p_pgrp; if ((flags & RFPGLOCK) && (plkgrp = p1->p_pgrp) != NULL) { pgref(plkgrp); lockmgr(&plkgrp->pg_lock, LK_SHARED); if (CURSIG_NOBLOCK(lp1)) { error = ERESTART; goto done; } } /* * 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 use the last ten processes; don't let root * exceed the limit. The variable nprocs is the current number of * processes, maxproc is the limit. */ uid = lp1->lwp_thread->td_ucred->cr_ruid; if ((nprocs >= maxproc - 10 && uid != 0) || nprocs >= maxproc) { if (ppsratecheck(&lastfail, &curfail, 1)) kprintf("maxproc limit exceeded by uid %d, please " "see tuning(7) and login.conf(5).\n", uid); tsleep(&forksleep, 0, "fork", hz / 2); error = EAGAIN; goto done; } /* * Increment the nprocs resource before blocking can occur. There * are hard-limits as to the number of processes that can run. */ atomic_add_int(&nprocs, 1); /* * Increment the count of procs running with this uid. This also * applies to root. */ ok = chgproccnt(lp1->lwp_thread->td_ucred->cr_ruidinfo, 1, plimit_getadjvalue(RLIMIT_NPROC)); if (!ok) { /* * Back out the process count */ atomic_add_int(&nprocs, -1); if (ppsratecheck(&lastfail, &curfail, 1)) { kprintf("maxproc limit of %jd " "exceeded by \"%s\" uid %d, " "please see tuning(7) and login.conf(5).\n", plimit_getadjvalue(RLIMIT_NPROC), p1->p_comm, uid); } tsleep(&forksleep, 0, "fork", hz / 2); error = EAGAIN; goto done; } /* * Allocate a new process, don't get fancy: zero the structure. */ p2 = kmalloc(sizeof(struct proc), M_PROC, M_WAITOK|M_ZERO); /* * Core initialization. SIDL is a safety state that protects the * partially initialized process once it starts getting hooked * into system structures and becomes addressable. * * We must be sure to acquire p2->p_token as well, we must hold it * once the process is on the allproc list to avoid things such * as competing modifications to p_flags. */ mycpu->gd_forkid += ncpus; p2->p_forkid = mycpu->gd_forkid + mycpu->gd_cpuid; p2->p_lasttid = 0; /* first tid will be 1 */ p2->p_stat = SIDL; /* * NOTE: Process 0 will not have a reaper, but process 1 (init) and * all other processes always will. */ if ((reap = p1->p_reaper) != NULL) { reaper_hold(reap); p2->p_reaper = reap; } else { p2->p_reaper = NULL; } RB_INIT(&p2->p_lwp_tree); spin_init(&p2->p_spin, "procfork1"); lwkt_token_init(&p2->p_token, "proc"); lwkt_gettoken(&p2->p_token); p2->p_uidpcpu = kmalloc(sizeof(*p2->p_uidpcpu) * ncpus, M_SUBPROC, M_WAITOK | M_ZERO); /* * Setup linkage for kernel based threading XXX lwp. Also add the * process to the allproclist. * * The process structure is addressable after this point. */ if (flags & RFTHREAD) { p2->p_peers = p1->p_peers; p1->p_peers = p2; p2->p_leader = p1->p_leader; } else { p2->p_leader = p2; } proc_add_allproc(p2); /* * Initialize the section which is copied verbatim from the parent. */ bcopy(&p1->p_startcopy, &p2->p_startcopy, ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy)); /* * Duplicate sub-structures as needed. Increase reference counts * on shared objects. * * NOTE: because we are now on the allproc list it is possible for * other consumers to gain temporary references to p2 * (p2->p_lock can change). */ if (p1->p_flags & P_PROFIL) startprofclock(p2); p2->p_ucred = crhold(lp1->lwp_thread->td_ucred); if (jailed(p2->p_ucred)) p2->p_flags |= P_JAILED; if (p2->p_args) refcount_acquire(&p2->p_args->ar_ref); p2->p_usched = p1->p_usched; /* XXX: verify copy of the secondary iosched stuff */ dsched_enter_proc(p2); if (flags & RFSIGSHARE) { p2->p_sigacts = p1->p_sigacts; refcount_acquire(&p2->p_sigacts->ps_refcnt); } else { p2->p_sigacts = kmalloc(sizeof(*p2->p_sigacts), M_SUBPROC, M_WAITOK); bcopy(p1->p_sigacts, p2->p_sigacts, sizeof(*p2->p_sigacts)); refcount_init(&p2->p_sigacts->ps_refcnt, 1); } if (flags & RFLINUXTHPN) p2->p_sigparent = SIGUSR1; else p2->p_sigparent = SIGCHLD; /* bump references to the text vnode (for procfs) */ p2->p_textvp = p1->p_textvp; if (p2->p_textvp) vref(p2->p_textvp); /* copy namecache handle to the text file */ if (p1->p_textnch.mount) cache_copy(&p1->p_textnch, &p2->p_textnch); /* * Handle file descriptors */ if (flags & RFCFDG) { p2->p_fd = fdinit(p1); fdtol = NULL; } else if (flags & RFFDG) { error = fdcopy(p1, &p2->p_fd); if (error != 0) { error = ENOMEM; goto done; } fdtol = NULL; } else { p2->p_fd = fdshare(p1); if (p1->p_fdtol == NULL) { p1->p_fdtol = filedesc_to_leader_alloc(NULL, p1->p_leader); } if ((flags & RFTHREAD) != 0) { /* * Shared file descriptor table and * shared process leaders. */ fdtol = p1->p_fdtol; fdtol->fdl_refcount++; } else { /* * Shared file descriptor table, and * different process leaders */ fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p2); } } p2->p_fdtol = fdtol; p2->p_limit = plimit_fork(p1); /* * Adjust depth for resource downscaling */ if ((p2->p_depth & 31) != 31) ++p2->p_depth; /* * Preserve some more flags in subprocess. P_PROFIL has already * been preserved. */ p2->p_flags |= p1->p_flags & P_SUGID; if (p1->p_session->s_ttyvp != NULL && (p1->p_flags & P_CONTROLT)) p2->p_flags |= P_CONTROLT; if (flags & RFPPWAIT) { p2->p_flags |= P_PPWAIT; if (p1->p_upmap) atomic_add_int(&p1->p_upmap->invfork, 1); } /* * Inherit the virtual kernel structure (allows a virtual kernel * to fork to simulate multiple cpus). */ if (p1->p_vkernel) vkernel_inherit(p1, p2); /* * Once we are on a pglist we may receive signals. XXX we might * race a ^C being sent to the process group by not receiving it * at all prior to this line. */ pgref(p1grp); lwkt_gettoken(&p1grp->pg_token); LIST_INSERT_AFTER(p1, p2, p_pglist); lwkt_reltoken(&p1grp->pg_token); /* * Attach the new process to its parent. * * If RFNOWAIT is set, the newly created process becomes a child * of the reaper (typically init). This effectively disassociates * the child from the parent. * * Temporarily hold pptr for the RFNOWAIT case to avoid ripouts. */ if (flags & RFNOWAIT) { pptr = reaper_get(reap); if (pptr == NULL) { pptr = initproc; PHOLD(pptr); } } else { pptr = p1; } p2->p_pptr = pptr; p2->p_ppid = pptr->p_pid; LIST_INIT(&p2->p_children); lwkt_gettoken(&pptr->p_token); LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); lwkt_reltoken(&pptr->p_token); if (flags & RFNOWAIT) PRELE(pptr); varsymset_init(&p2->p_varsymset, &p1->p_varsymset); callout_init_mp(&p2->p_ithandle); #ifdef KTRACE /* * Copy traceflag and tracefile if enabled. If not inherited, * these were zeroed above but we still could have a trace race * so make sure p2's p_tracenode is NULL. */ if ((p1->p_traceflag & KTRFAC_INHERIT) && p2->p_tracenode == NULL) { p2->p_traceflag = p1->p_traceflag; p2->p_tracenode = ktrinherit(p1->p_tracenode); } #endif /* * This begins the section where we must prevent the parent * from being messed with too heavily while we run through the * fork operation. * * Gets PRELE'd in the caller in start_forked_proc(). * * Create the first lwp associated with the new proc. It will * return via a different execution path later, directly into * userland, after it was put on the runq by start_forked_proc(). */ PHOLD(p1); lp2 = lwp_fork1(lp1, p2, flags, NULL); vm_fork(p1, p2, lp2, flags); if ((flags & RFMEM) == 0) wake_umtx_threads(p1); lwp_fork2(lp1, p2, lp2, flags); if (flags == (RFFDG | RFPROC | RFPGLOCK)) { mycpu->gd_cnt.v_forks++; mycpu->gd_cnt.v_forkpages += btoc(p2->p_vmspace->vm_dsize) + btoc(p2->p_vmspace->vm_ssize); } else if (flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK)) { mycpu->gd_cnt.v_vforks++; mycpu->gd_cnt.v_vforkpages += btoc(p2->p_vmspace->vm_dsize) + btoc(p2->p_vmspace->vm_ssize); } else if (p1 == &proc0) { mycpu->gd_cnt.v_kthreads++; mycpu->gd_cnt.v_kthreadpages += btoc(p2->p_vmspace->vm_dsize) + btoc(p2->p_vmspace->vm_ssize); } else { mycpu->gd_cnt.v_rforks++; mycpu->gd_cnt.v_rforkpages += btoc(p2->p_vmspace->vm_dsize) + btoc(p2->p_vmspace->vm_ssize); } /* * Both processes are set up, now check if any loadable modules want * to adjust anything. * What if they have an error? XXX */ TAILQ_FOREACH(ep, &fork_list, next) { (*ep->function)(p1, p2, flags); } /* * Set the start time. Note that the process is not runnable. The * caller is responsible for making it runnable. */ microtime(&p2->p_start); p2->p_acflag = AFORK; /* * tell any interested parties about the new process */ KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid); /* * Return child proc pointer to parent. */ *procp = p2; error = 0; done: if (p2) lwkt_reltoken(&p2->p_token); lwkt_reltoken(&p1->p_token); if (plkgrp) { lockmgr(&plkgrp->pg_lock, LK_RELEASE); pgrel(plkgrp); } return (error); } /* * The first part of lwp_fork*() allocates enough of the new lwp that * vm_fork() can use it to deal with /dev/lpmap mappings. */ static struct lwp * lwp_fork1(struct lwp *lp1, struct proc *destproc, int flags, const cpumask_t *mask) { struct lwp *lp2; lp2 = kmalloc(sizeof(struct lwp), M_LWP, M_WAITOK|M_ZERO); lp2->lwp_proc = destproc; lp2->lwp_stat = LSRUN; bcopy(&lp1->lwp_startcopy, &lp2->lwp_startcopy, (unsigned) ((caddr_t)&lp2->lwp_endcopy - (caddr_t)&lp2->lwp_startcopy)); if (mask != NULL) lp2->lwp_cpumask = *mask; lwkt_token_init(&lp2->lwp_token, "lwp_token"); TAILQ_INIT(&lp2->lwp_lpmap_backing_list); spin_init(&lp2->lwp_spin, "lwptoken"); /* * Use the same TID for the first thread in the new process after * a fork or vfork. This is needed to keep pthreads and /dev/lpmap * sane. In particular a consequence of implementing the per-thread * /dev/lpmap map code makes this mandatory. * * NOTE: exec*() will reset the TID to 1 to keep things sane in that * department too. * * NOTE: In the case of lwp_create(), this TID represents a conflict * which will be resolved in lwp_fork2(), but in the case of * a fork(), the TID has to be correct or vm_fork() will not * keep the correct lpmap. */ lp2->lwp_tid = lp1->lwp_tid; return lp2; } /* * The second part of lwp_fork*() */ static void lwp_fork2(struct lwp *lp1, struct proc *destproc, struct lwp *lp2, int flags) { globaldata_t gd = mycpu; struct thread *td2; lp2->lwp_vmspace = destproc->p_vmspace; /* * Reset the sigaltstack if memory is shared, otherwise inherit * it. */ if (flags & RFMEM) { lp2->lwp_sigstk.ss_flags = SS_DISABLE; lp2->lwp_sigstk.ss_size = 0; lp2->lwp_sigstk.ss_sp = NULL; lp2->lwp_flags &= ~LWP_ALTSTACK; } else { lp2->lwp_flags |= lp1->lwp_flags & LWP_ALTSTACK; } /* * Set cpbase to the last timeout that occured (not the upcoming * timeout). * * A critical section is required since a timer IPI can update * scheduler specific data. */ crit_enter(); lp2->lwp_cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; destproc->p_usched->heuristic_forking(lp1, lp2); crit_exit(); CPUMASK_ANDMASK(lp2->lwp_cpumask, usched_mastermask); /* * Assign the thread to the current cpu to begin with so we * can manipulate it. */ td2 = lwkt_alloc_thread(NULL, LWKT_THREAD_STACK, gd->gd_cpuid, 0); lp2->lwp_thread = td2; td2->td_wakefromcpu = gd->gd_cpuid; td2->td_ucred = crhold(destproc->p_ucred); td2->td_proc = destproc; td2->td_lwp = lp2; td2->td_switch = cpu_heavy_switch; #ifdef NO_LWKT_SPLIT_USERPRI lwkt_setpri(td2, TDPRI_USER_NORM); #else lwkt_setpri(td2, TDPRI_KERN_USER); #endif lwkt_set_comm(td2, "%s", destproc->p_comm); /* * cpu_fork will copy and update the pcb, set up the kernel stack, * and make the child ready to run. */ cpu_fork(lp1, lp2, flags); kqueue_init(&lp2->lwp_kqueue, destproc->p_fd); /* * Associate the new thread with destproc, after we've set most of * it up and gotten its related td2 installed. Otherwise we can * race other random kernel code that iterates LWPs and expects the * thread to be assigned. * * Leave 2 bits open so the pthreads library can optimize locks * by combining the TID with a few Lock-related flags. */ while (lwp_rb_tree_RB_INSERT(&destproc->p_lwp_tree, lp2) != NULL) { ++lp2->lwp_tid; if (lp2->lwp_tid == 0 || lp2->lwp_tid == 0x3FFFFFFF) lp2->lwp_tid = 1; } destproc->p_lasttid = lp2->lwp_tid; destproc->p_nthreads++; /* * This flag is set and never cleared. It means that the process * was threaded at some point. Used to improve exit performance. */ pmap_maybethreaded(&destproc->p_vmspace->vm_pmap); destproc->p_flags |= P_MAYBETHREADED; /* * If the original lp had a lpmap and a non-zero blockallsigs * count, give the lp for the forked process the same count. * * This makes the user code and expectations less confusing * in terms of unwinding locks and also allows userland to start * the forked process with signals blocked via the blockallsigs() * mechanism if desired. */ if (lp1->lwp_lpmap && (lp1->lwp_lpmap->blockallsigs & 0x7FFFFFFF)) { lwp_usermap(lp2, 0); if (lp2->lwp_lpmap) { lp2->lwp_lpmap->blockallsigs = lp1->lwp_lpmap->blockallsigs; } } } /* * The next two functionms are general routines to handle adding/deleting * items on the fork callout list. * * at_fork(): * Take the arguments given and put them onto the fork callout list, * However first make sure that it's not already there. * Returns 0 on success or a standard error number. */ int at_fork(forklist_fn function) { struct forklist *ep; #ifdef INVARIANTS /* let the programmer know if he's been stupid */ if (rm_at_fork(function)) { kprintf("WARNING: fork callout entry (%p) already present\n", function); } #endif ep = kmalloc(sizeof(*ep), M_ATFORK, M_WAITOK|M_ZERO); ep->function = function; TAILQ_INSERT_TAIL(&fork_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_fork(forklist_fn function) { struct forklist *ep; TAILQ_FOREACH(ep, &fork_list, next) { if (ep->function == function) { TAILQ_REMOVE(&fork_list, ep, next); kfree(ep, M_ATFORK); return(1); } } return (0); } /* * Add a forked process to the run queue after any remaining setup, such * as setting the fork handler, has been completed. * * p2 is held by the caller. */ void start_forked_proc(struct lwp *lp1, struct proc *p2) { struct lwp *lp2 = ONLY_LWP_IN_PROC(p2); int pflags; /* * Move from SIDL to RUN queue, and activate the process's thread. * Activation of the thread effectively makes the process "a" * current process, so we do not setrunqueue(). * * YYY setrunqueue works here but we should clean up the trampoline * code so we just schedule the LWKT thread and let the trampoline * deal with the userland scheduler on return to userland. */ KASSERT(p2->p_stat == SIDL, ("cannot start forked process, bad status: %p", p2)); p2->p_usched->resetpriority(lp2); crit_enter(); p2->p_stat = SACTIVE; lp2->lwp_stat = LSRUN; p2->p_usched->setrunqueue(lp2); crit_exit(); /* * Now can be swapped. */ PRELE(lp1->lwp_proc); /* * Preserve synchronization semantics of vfork. P_PPWAIT is set in * the child until it has retired the parent's resources. The parent * must wait for the flag to be cleared by the child. * * Interlock the flag/tsleep with atomic ops to avoid unnecessary * p_token conflicts. * * XXX Is this use of an atomic op on a field that is not normally * manipulated with atomic ops ok? */ while ((pflags = p2->p_flags) & P_PPWAIT) { cpu_ccfence(); tsleep_interlock(lp1->lwp_proc, 0); if (atomic_cmpset_int(&p2->p_flags, pflags, pflags)) tsleep(lp1->lwp_proc, PINTERLOCKED, "ppwait", 0); } } /* * procctl (idtype_t idtype, id_t id, int cmd, void *arg) */ int sys_procctl(struct sysmsg *sysmsg, const struct procctl_args *uap) { struct proc *p = curproc; struct proc *p2; struct sysreaper *reap; union reaper_info udata; int error; if (uap->idtype != P_PID) return EINVAL; if (uap->id != 0 && uap->id != (id_t)p->p_pid) return EINVAL; switch(uap->cmd) { case PROC_REAP_ACQUIRE: lwkt_gettoken(&p->p_token); reap = kmalloc(sizeof(*reap), M_REAPER, M_WAITOK|M_ZERO); if (p->p_reaper == NULL || p->p_reaper->p != p) { reaper_init(p, reap); error = 0; } else { kfree(reap, M_REAPER); error = EALREADY; } lwkt_reltoken(&p->p_token); break; case PROC_REAP_RELEASE: lwkt_gettoken(&p->p_token); release_again: reap = p->p_reaper; KKASSERT(reap != NULL); if (reap->p == p) { reaper_hold(reap); /* in case of thread race */ lockmgr(&reap->lock, LK_EXCLUSIVE); if (reap->p != p) { lockmgr(&reap->lock, LK_RELEASE); reaper_drop(reap); goto release_again; } reap->p = NULL; p->p_reaper = reap->parent; if (p->p_reaper) reaper_hold(p->p_reaper); lockmgr(&reap->lock, LK_RELEASE); reaper_drop(reap); /* our ref */ reaper_drop(reap); /* old p_reaper ref */ error = 0; } else { error = ENOTCONN; } lwkt_reltoken(&p->p_token); break; case PROC_REAP_STATUS: bzero(&udata, sizeof(udata)); lwkt_gettoken_shared(&p->p_token); if ((reap = p->p_reaper) != NULL && reap->p == p) { udata.status.flags = reap->flags; udata.status.refs = reap->refs - 1; /* minus ours */ } p2 = LIST_FIRST(&p->p_children); udata.status.pid_head = p2 ? p2->p_pid : -1; lwkt_reltoken(&p->p_token); if (uap->data) { error = copyout(&udata, uap->data, sizeof(udata.status)); } else { error = 0; } break; case PROC_PDEATHSIG_CTL: error = EINVAL; if (uap->data) { int dsig = 0; error = copyin(uap->data, &dsig, sizeof(dsig)); if (error == 0 && dsig >= 0 && dsig <= _SIG_MAXSIG) p->p_deathsig = dsig; } break; case PROC_PDEATHSIG_STATUS: error = EINVAL; if (uap->data) { error = copyout(&p->p_deathsig, uap->data, sizeof(p->p_deathsig)); } break; default: error = EINVAL; break; } return error; } /* * Bump ref on reaper, preventing destruction */ void reaper_hold(struct sysreaper *reap) { KKASSERT(reap->refs > 0); refcount_acquire(&reap->refs); } /* * Drop ref on reaper, destroy the structure on the 1->0 * transition and loop on the parent. */ void reaper_drop(struct sysreaper *next) { struct sysreaper *reap; while ((reap = next) != NULL) { if (refcount_release(&reap->refs)) { next = reap->parent; KKASSERT(reap->p == NULL); lockmgr(&reaper_lock, LK_EXCLUSIVE); reap->parent = NULL; kfree(reap, M_REAPER); lockmgr(&reaper_lock, LK_RELEASE); } else { next = NULL; } } } /* * Initialize a static or newly allocated reaper structure */ void reaper_init(struct proc *p, struct sysreaper *reap) { reap->parent = p->p_reaper; reap->p = p; if (p == initproc) { reap->flags = REAPER_STAT_OWNED | REAPER_STAT_REALINIT; reap->refs = 2; } else { reap->flags = REAPER_STAT_OWNED; reap->refs = 1; } lockinit(&reap->lock, "subrp", 0, 0); cpu_sfence(); p->p_reaper = reap; } /* * Called with p->p_token held during exit. * * This is a bit simpler than RELEASE because there are no threads remaining * to race. We only release if we own the reaper, the exit code will handle * the final p_reaper release. */ struct sysreaper * reaper_exit(struct proc *p) { struct sysreaper *reap; /* * Release acquired reaper */ if ((reap = p->p_reaper) != NULL && reap->p == p) { lockmgr(&reap->lock, LK_EXCLUSIVE); p->p_reaper = reap->parent; if (p->p_reaper) reaper_hold(p->p_reaper); reap->p = NULL; lockmgr(&reap->lock, LK_RELEASE); reaper_drop(reap); } /* * Return and clear reaper (caller is holding p_token for us) * (reap->p does not equal p). Caller must drop it. */ if ((reap = p->p_reaper) != NULL) { p->p_reaper = NULL; } return reap; } /* * Return a held (PHOLD) process representing the reaper for process (p). * NULL should not normally be returned. Caller should PRELE() the returned * reaper process when finished. * * Remove dead internal nodes while we are at it. * * Process (p)'s token must be held on call. * The returned process's token is NOT acquired by this routine. */ struct proc * reaper_get(struct sysreaper *reap) { struct sysreaper *next; struct proc *reproc; if (reap == NULL) return NULL; /* * Extra hold for loop */ reaper_hold(reap); while (reap) { lockmgr(&reap->lock, LK_SHARED); if (reap->p) { /* * Probable reaper */ if (reap->p) { reproc = reap->p; PHOLD(reproc); lockmgr(&reap->lock, LK_RELEASE); reaper_drop(reap); return reproc; } /* * Raced, try again */ lockmgr(&reap->lock, LK_RELEASE); continue; } /* * Traverse upwards in the reaper topology, destroy * dead internal nodes when possible. * * NOTE: Our ref on next means that a dead node should * have 2 (ours and reap->parent's). */ next = reap->parent; while (next) { reaper_hold(next); if (next->refs == 2 && next->p == NULL) { lockmgr(&reap->lock, LK_RELEASE); lockmgr(&reap->lock, LK_EXCLUSIVE); if (next->refs == 2 && reap->parent == next && next->p == NULL) { /* * reap->parent inherits ref from next. */ reap->parent = next->parent; next->parent = NULL; reaper_drop(next); /* ours */ reaper_drop(next); /* old parent */ next = reap->parent; continue; /* possible chain */ } } break; } lockmgr(&reap->lock, LK_RELEASE); reaper_drop(reap); reap = next; } return NULL; } /* * Test that the sender is allowed to send a signal to the target. * The sender process is assumed to have a stable reaper. The * target can be e.g. from a scan callback. * * Target cannot be the reaper process itself unless reaper_ok is specified, * or sender == target. */ int reaper_sigtest(struct proc *sender, struct proc *target, int reaper_ok) { struct sysreaper *sreap; struct sysreaper *reap; int r; sreap = sender->p_reaper; if (sreap == NULL) return 1; if (sreap == target->p_reaper) { if (sreap->p == target && sreap->p != sender && reaper_ok == 0) return 0; return 1; } lockmgr(&reaper_lock, LK_SHARED); r = 0; for (reap = target->p_reaper; reap; reap = reap->parent) { if (sreap == reap) { if (sreap->p != target || reaper_ok) r = 1; break; } } lockmgr(&reaper_lock, LK_RELEASE); return r; }