static void do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *td2, struct vmspace *vm2, struct file *fp_procdesc) { struct proc *p1, *pptr; int trypid; struct filedesc *fd; struct filedesc_to_leader *fdtol; struct sigacts *newsigacts; sx_assert(&proctree_lock, SX_SLOCKED); sx_assert(&allproc_lock, SX_XLOCKED); p1 = td->td_proc; trypid = fork_findpid(fr->fr_flags); sx_sunlock(&proctree_lock); p2->p_state = PRS_NEW; /* protect against others */ p2->p_pid = trypid; AUDIT_ARG_PID(p2->p_pid); LIST_INSERT_HEAD(&allproc, p2, p_list); allproc_gen++; LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash); tidhash_add(td2); PROC_LOCK(p2); PROC_LOCK(p1); sx_xunlock(&allproc_lock); bcopy(&p1->p_startcopy, &p2->p_startcopy, __rangeof(struct proc, p_startcopy, p_endcopy)); pargs_hold(p2->p_args); PROC_UNLOCK(p1); bzero(&p2->p_startzero, __rangeof(struct proc, p_startzero, p_endzero)); /* Tell the prison that we exist. */ prison_proc_hold(p2->p_ucred->cr_prison); PROC_UNLOCK(p2); /* * Malloc things while we don't hold any locks. */ if (fr->fr_flags & RFSIGSHARE) newsigacts = NULL; else newsigacts = sigacts_alloc(); /* * Copy filedesc. */ if (fr->fr_flags & RFCFDG) { fd = fdinit(p1->p_fd, false); fdtol = NULL; } else if (fr->fr_flags & RFFDG) { fd = fdcopy(p1->p_fd); fdtol = NULL; } else { fd = fdshare(p1->p_fd); if (p1->p_fdtol == NULL) p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL, p1->p_leader); if ((fr->fr_flags & RFTHREAD) != 0) { /* * Shared file descriptor table, and shared * process leaders. */ fdtol = p1->p_fdtol; FILEDESC_XLOCK(p1->p_fd); fdtol->fdl_refcount++; FILEDESC_XUNLOCK(p1->p_fd); } else { /* * Shared file descriptor table, and different * process leaders. */ fdtol = filedesc_to_leader_alloc(p1->p_fdtol, p1->p_fd, p2); } } /* * 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. */ PROC_LOCK(p2); PROC_LOCK(p1); bzero(&td2->td_startzero, __rangeof(struct thread, td_startzero, td_endzero)); bcopy(&td->td_startcopy, &td2->td_startcopy, __rangeof(struct thread, td_startcopy, td_endcopy)); bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name)); td2->td_sigstk = td->td_sigstk; td2->td_flags = TDF_INMEM; td2->td_lend_user_pri = PRI_MAX; #ifdef VIMAGE td2->td_vnet = NULL; td2->td_vnet_lpush = NULL; #endif /* * Allow the scheduler to initialize the child. */ thread_lock(td); sched_fork(td, td2); thread_unlock(td); /* * Duplicate sub-structures as needed. * Increase reference counts on shared objects. */ p2->p_flag = P_INMEM; p2->p_flag2 = p1->p_flag2 & (P2_NOTRACE | P2_NOTRACE_EXEC | P2_TRAPCAP); p2->p_swtick = ticks; if (p1->p_flag & P_PROFIL) startprofclock(p2); /* * Whilst the proc lock is held, copy the VM domain data out * using the VM domain method. */ vm_domain_policy_init(&p2->p_vm_dom_policy); vm_domain_policy_localcopy(&p2->p_vm_dom_policy, &p1->p_vm_dom_policy); if (fr->fr_flags & RFSIGSHARE) { p2->p_sigacts = sigacts_hold(p1->p_sigacts); } else { sigacts_copy(newsigacts, p1->p_sigacts); p2->p_sigacts = newsigacts; } if (fr->fr_flags & RFTSIGZMB) p2->p_sigparent = RFTSIGNUM(fr->fr_flags); else if (fr->fr_flags & RFLINUXTHPN) p2->p_sigparent = SIGUSR1; else p2->p_sigparent = SIGCHLD; p2->p_textvp = p1->p_textvp; p2->p_fd = fd; p2->p_fdtol = fdtol; if (p1->p_flag2 & P2_INHERIT_PROTECTED) { p2->p_flag |= P_PROTECTED; p2->p_flag2 |= P2_INHERIT_PROTECTED; } /* * p_limit is copy-on-write. Bump its refcount. */ lim_fork(p1, p2); thread_cow_get_proc(td2, p2); pstats_fork(p1->p_stats, p2->p_stats); PROC_UNLOCK(p1); PROC_UNLOCK(p2); /* Bump references to the text vnode (for procfs). */ if (p2->p_textvp) vrefact(p2->p_textvp); /* * Set up linkage for kernel based threading. */ if ((fr->fr_flags & RFTHREAD) != 0) { mtx_lock(&ppeers_lock); p2->p_peers = p1->p_peers; p1->p_peers = p2; p2->p_leader = p1->p_leader; mtx_unlock(&ppeers_lock); PROC_LOCK(p1->p_leader); if ((p1->p_leader->p_flag & P_WEXIT) != 0) { PROC_UNLOCK(p1->p_leader); /* * The task leader is exiting, so process p1 is * going to be killed shortly. Since p1 obviously * isn't dead yet, we know that the leader is either * sending SIGKILL's to all the processes in this * task or is sleeping waiting for all the peers to * exit. We let p1 complete the fork, but we need * to go ahead and kill the new process p2 since * the task leader may not get a chance to send * SIGKILL to it. We leave it on the list so that * the task leader will wait for this new process * to commit suicide. */ PROC_LOCK(p2); kern_psignal(p2, SIGKILL); PROC_UNLOCK(p2); } else PROC_UNLOCK(p1->p_leader); } else { p2->p_peers = NULL; p2->p_leader = p2; } sx_xlock(&proctree_lock); PGRP_LOCK(p1->p_pgrp); PROC_LOCK(p2); PROC_LOCK(p1); /* * Preserve some more flags in subprocess. P_PROFIL has already * been preserved. */ p2->p_flag |= p1->p_flag & P_SUGID; td2->td_pflags |= (td->td_pflags & TDP_ALTSTACK) | TDP_FORKING; SESS_LOCK(p1->p_session); if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT) p2->p_flag |= P_CONTROLT; SESS_UNLOCK(p1->p_session); if (fr->fr_flags & RFPPWAIT) p2->p_flag |= P_PPWAIT; p2->p_pgrp = p1->p_pgrp; LIST_INSERT_AFTER(p1, p2, p_pglist); PGRP_UNLOCK(p1->p_pgrp); LIST_INIT(&p2->p_children); LIST_INIT(&p2->p_orphans); callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0); /* * If PF_FORK is set, the child process inherits the * procfs ioctl flags from its parent. */ if (p1->p_pfsflags & PF_FORK) { p2->p_stops = p1->p_stops; p2->p_pfsflags = p1->p_pfsflags; } /* * This begins the section where we must prevent the parent * from being swapped. */ _PHOLD(p1); PROC_UNLOCK(p1); /* * Attach the new process to its parent. * * If RFNOWAIT is set, the newly created process becomes a child * of init. This effectively disassociates the child from the * parent. */ if ((fr->fr_flags & RFNOWAIT) != 0) { pptr = p1->p_reaper; p2->p_reaper = pptr; } else { p2->p_reaper = (p1->p_treeflag & P_TREE_REAPER) != 0 ? p1 : p1->p_reaper; pptr = p1; } p2->p_pptr = pptr; LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling); LIST_INIT(&p2->p_reaplist); LIST_INSERT_HEAD(&p2->p_reaper->p_reaplist, p2, p_reapsibling); if (p2->p_reaper == p1) p2->p_reapsubtree = p2->p_pid; sx_xunlock(&proctree_lock); /* Inform accounting that we have forked. */ p2->p_acflag = AFORK; PROC_UNLOCK(p2); #ifdef KTRACE ktrprocfork(p1, p2); #endif /* * Finish creating the child process. It will return via a different * execution path later. (ie: directly into user mode) */ vm_forkproc(td, p2, td2, vm2, fr->fr_flags); if (fr->fr_flags == (RFFDG | RFPROC)) { VM_CNT_INC(v_forks); VM_CNT_ADD(v_forkpages, p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize); } else if (fr->fr_flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) { VM_CNT_INC(v_vforks); VM_CNT_ADD(v_vforkpages, p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize); } else if (p1 == &proc0) { VM_CNT_INC(v_kthreads); VM_CNT_ADD(v_kthreadpages, p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize); } else { VM_CNT_INC(v_rforks); VM_CNT_ADD(v_rforkpages, p2->p_vmspace->vm_dsize + p2->p_vmspace->vm_ssize); } /* * Associate the process descriptor with the process before anything * can happen that might cause that process to need the descriptor. * However, don't do this until after fork(2) can no longer fail. */ if (fr->fr_flags & RFPROCDESC) procdesc_new(p2, fr->fr_pd_flags); /* * Both processes are set up, now check if any loadable modules want * to adjust anything. */ EVENTHANDLER_INVOKE(process_fork, p1, p2, fr->fr_flags); /* * Set the child start time and mark the process as being complete. */ PROC_LOCK(p2); PROC_LOCK(p1); microuptime(&p2->p_stats->p_start); PROC_SLOCK(p2); p2->p_state = PRS_NORMAL; PROC_SUNLOCK(p2); #ifdef KDTRACE_HOOKS /* * Tell the DTrace fasttrap provider about the new process so that any * tracepoints inherited from the parent can be removed. We have to do * this only after p_state is PRS_NORMAL since the fasttrap module will * use pfind() later on. */ if ((fr->fr_flags & RFMEM) == 0 && dtrace_fasttrap_fork) dtrace_fasttrap_fork(p1, p2); #endif /* * Hold the process so that it cannot exit after we make it runnable, * but before we wait for the debugger. */ _PHOLD(p2); if (p1->p_ptevents & PTRACE_FORK) { /* * Arrange for debugger to receive the fork event. * * We can report PL_FLAG_FORKED regardless of * P_FOLLOWFORK settings, but it does not make a sense * for runaway child. */ td->td_dbgflags |= TDB_FORK; td->td_dbg_forked = p2->p_pid; td2->td_dbgflags |= TDB_STOPATFORK; } if (fr->fr_flags & RFPPWAIT) { td->td_pflags |= TDP_RFPPWAIT; td->td_rfppwait_p = p2; td->td_dbgflags |= TDB_VFORK; } PROC_UNLOCK(p2); /* * Now can be swapped. */ _PRELE(p1); PROC_UNLOCK(p1); /* * Tell any interested parties about the new process. */ knote_fork(p1->p_klist, p2->p_pid); SDT_PROBE3(proc, , , create, p2, p1, fr->fr_flags); if (fr->fr_flags & RFPROCDESC) { procdesc_finit(p2->p_procdesc, fp_procdesc); fdrop(fp_procdesc, td); } if ((fr->fr_flags & RFSTOPPED) == 0) { /* * If RFSTOPPED not requested, make child runnable and * add to run queue. */ thread_lock(td2); TD_SET_CAN_RUN(td2); sched_add(td2, SRQ_BORING); thread_unlock(td2); if (fr->fr_pidp != NULL) *fr->fr_pidp = p2->p_pid; } else { *fr->fr_procp = p2; } PROC_LOCK(p2); /* * Wait until debugger is attached to child. */ while (td2->td_proc == p2 && (td2->td_dbgflags & TDB_STOPATFORK) != 0) cv_wait(&p2->p_dbgwait, &p2->p_mtx); _PRELE(p2); racct_proc_fork_done(p2); PROC_UNLOCK(p2); }
/* * Create a kernel thread. It shares its address space * with proc0 - ie: kernel only. * * func is the function to start. * arg is the parameter to pass to function on first startup. * newtdp is the return value pointing to the thread's struct thread. * ** XXX fix this --> flags are flags to fork1 (in unistd.h) * fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.). */ int kthread_add(void (*func)(void *), void *arg, struct proc *p, struct thread **newtdp, int flags, int pages, const char *fmt, ...) { va_list ap; struct thread *newtd, *oldtd; if (!proc0.p_stats) panic("kthread_add called too soon"); /* If no process supplied, put it on proc0 */ if (p == NULL) p = &proc0; /* Initialize our new td */ newtd = thread_alloc(pages); if (newtd == NULL) return (ENOMEM); PROC_LOCK(p); oldtd = FIRST_THREAD_IN_PROC(p); bzero(&newtd->td_startzero, __rangeof(struct thread, td_startzero, td_endzero)); bcopy(&oldtd->td_startcopy, &newtd->td_startcopy, __rangeof(struct thread, td_startcopy, td_endcopy)); /* set up arg0 for 'ps', et al */ va_start(ap, fmt); vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap); va_end(ap); newtd->td_proc = p; /* needed for cpu_set_upcall */ /* XXX optimise this probably? */ /* On x86 (and probably the others too) it is way too full of junk */ /* Needs a better name */ cpu_set_upcall(newtd, oldtd); /* put the designated function(arg) as the resume context */ cpu_set_fork_handler(newtd, func, arg); newtd->td_pflags |= TDP_KTHREAD; thread_cow_get_proc(newtd, p); /* this code almost the same as create_thread() in kern_thr.c */ p->p_flag |= P_HADTHREADS; thread_link(newtd, p); thread_lock(oldtd); /* let the scheduler know about these things. */ sched_fork_thread(oldtd, newtd); TD_SET_CAN_RUN(newtd); thread_unlock(oldtd); PROC_UNLOCK(p); tidhash_add(newtd); /* Avoid inheriting affinity from a random parent. */ cpuset_setthread(newtd->td_tid, cpuset_root); /* Delay putting it on the run queue until now. */ if (!(flags & RFSTOPPED)) { thread_lock(newtd); sched_add(newtd, SRQ_BORING); thread_unlock(newtd); } if (newtdp) *newtdp = newtd; return 0; }