X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fexit.c;h=17987bc019b35a5ebe039513c70706fb426ca1ee;hb=e0ff8aa1acd079b70e796571917ae0449b7c465b;hp=99e79125ef031a26e6208aaac833b5e1fa493993;hpb=16c70f8c1b54b61c3b951b6fb220df250fe09b32;p=linux-2.6.git diff --git a/kernel/exit.c b/kernel/exit.c index 99e79125e..17987bc01 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -21,7 +21,6 @@ #include #include #include -#include #include #include #include @@ -143,10 +142,10 @@ void release_task(struct task_struct * p) struct task_struct *leader; int zap_leader; repeat: - tracehook_release_task(p); atomic_dec(&p->user->processes); write_lock_irq(&tasklist_lock); - BUG_ON(tracehook_check_released(p)); + ptrace_unlink(p); + BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children)); __exit_signal(p); /* @@ -223,10 +222,10 @@ static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task) do_each_task_pid(pgrp, PIDTYPE_PGID, p) { if (p == ignored_task || p->exit_state - || p->parent->pid == 1) + || p->real_parent->pid == 1) continue; - if (process_group(p->parent) != pgrp - && p->parent->signal->session == p->signal->session) { + if (process_group(p->real_parent) != pgrp + && p->real_parent->signal->session == p->signal->session) { ret = 0; break; } @@ -254,6 +253,16 @@ static int has_stopped_jobs(int pgrp) if (p->state != TASK_STOPPED) continue; + /* If p is stopped by a debugger on a signal that won't + stop it, then don't count p as stopped. This isn't + perfect but it's a good approximation. */ + if (unlikely (p->ptrace) + && p->exit_code != SIGSTOP + && p->exit_code != SIGTSTP + && p->exit_code != SIGTTOU + && p->exit_code != SIGTTIN) + continue; + retval = 1; break; } while_each_task_pid(pgrp, PIDTYPE_PGID, p); @@ -276,9 +285,11 @@ static void reparent_to_init(void) { write_lock_irq(&tasklist_lock); + ptrace_unlink(current); /* Reparent to init */ remove_parent(current); current->parent = child_reaper; + current->real_parent = child_reaper; add_parent(current); /* Set the exit signal to SIGCHLD so we signal init on exit */ @@ -385,9 +396,7 @@ void daemonize(const char *name, ...) exit_mm(current); set_special_pids(1, 1); - mutex_lock(&tty_mutex); - current->signal->tty = NULL; - mutex_unlock(&tty_mutex); + proc_clear_tty(current); /* Block and flush all signals */ sigfillset(&blocked); @@ -591,11 +600,11 @@ choose_new_parent(struct task_struct *p, struct task_struct *reaper) * the parent is not a zombie. */ BUG_ON(p == reaper || reaper->exit_state); - p->parent = reaper; + p->real_parent = reaper; } static void -reparent_thread(struct task_struct *p, struct task_struct *father) +reparent_thread(struct task_struct *p, struct task_struct *father, int traced) { /* We don't want people slaying init. */ if (p->exit_signal != -1) @@ -606,14 +615,35 @@ reparent_thread(struct task_struct *p, struct task_struct *father) group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); /* Move the child from its dying parent to the new one. */ - list_move_tail(&p->sibling, &p->parent->children); + if (unlikely(traced)) { + /* Preserve ptrace links if someone else is tracing this child. */ + list_del_init(&p->ptrace_list); + if (p->parent != p->real_parent) + list_add(&p->ptrace_list, &p->real_parent->ptrace_children); + } else { + /* If this child is being traced, then we're the one tracing it + * anyway, so let go of it. + */ + p->ptrace = 0; + remove_parent(p); + p->parent = p->real_parent; + add_parent(p); - /* If we'd notified the old parent about this child's death, - * also notify the new parent. - */ - if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && - thread_group_empty(p)) - do_notify_parent(p, p->exit_signal); + /* If we'd notified the old parent about this child's death, + * also notify the new parent. + */ + if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && + thread_group_empty(p)) + do_notify_parent(p, p->exit_signal); + else if (p->state == TASK_TRACED) { + /* + * If it was at a trace stop, turn it into + * a normal stop since it's no longer being + * traced. + */ + ptrace_untrace(p); + } + } /* * process group orphan check @@ -639,7 +669,7 @@ reparent_thread(struct task_struct *p, struct task_struct *father) * the global child reaper process (ie "init") */ static void -forget_original_parent(struct task_struct *father) +forget_original_parent(struct task_struct *father, struct list_head *to_release) { struct task_struct *p, *reaper = father; struct list_head *_p, *_n; @@ -652,10 +682,48 @@ forget_original_parent(struct task_struct *father) } } while (reaper->exit_state); + /* + * There are only two places where our children can be: + * + * - in our child list + * - in our ptraced child list + * + * Search them and reparent children. + */ list_for_each_safe(_p, _n, &father->children) { + int ptrace; p = list_entry(_p, struct task_struct, sibling); - choose_new_parent(p, vx_child_reaper(p)); - reparent_thread(p, father); + + ptrace = p->ptrace; + + /* if father isn't the real parent, then ptrace must be enabled */ + BUG_ON(father != p->real_parent && !ptrace); + + if (father == p->real_parent) { + /* reparent with a reaper, real father it's us */ + choose_new_parent(p, vx_child_reaper(p)); + reparent_thread(p, father, 0); + } else { + /* reparent ptraced task to its real parent */ + __ptrace_unlink (p); + if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && + thread_group_empty(p)) + do_notify_parent(p, p->exit_signal); + } + + /* + * if the ptraced child is a zombie with exit_signal == -1 + * we must collect it before we exit, or it will remain + * zombie forever since we prevented it from self-reap itself + * while it was being traced by us, to be able to see it in wait4. + */ + if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1)) + list_add(&p->ptrace_list, to_release); + } + list_for_each_safe(_p, _n, &father->ptrace_children) { + p = list_entry(_p, struct task_struct, ptrace_list); + choose_new_parent(p, reaper); + reparent_thread(p, father, 1); } } @@ -667,8 +735,7 @@ static void exit_notify(struct task_struct *tsk) { int state; struct task_struct *t; - int noreap; - void *cookie; + struct list_head ptrace_dead, *_p, *_n; if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT) && !thread_group_empty(tsk)) { @@ -704,8 +771,10 @@ static void exit_notify(struct task_struct *tsk) * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) */ - forget_original_parent(tsk); + INIT_LIST_HEAD(&ptrace_dead); + forget_original_parent(tsk, &ptrace_dead); BUG_ON(!list_empty(&tsk->children)); + BUG_ON(!list_empty(&tsk->ptrace_children)); /* * Check to see if any process groups have become orphaned @@ -717,7 +786,7 @@ static void exit_notify(struct task_struct *tsk) * is about to become orphaned. */ - t = tsk->parent; + t = tsk->real_parent; if ((process_group(t) != process_group(tsk)) && (t->signal->session == tsk->signal->session) && @@ -749,18 +818,32 @@ static void exit_notify(struct task_struct *tsk) && !capable(CAP_KILL)) tsk->exit_signal = SIGCHLD; - if (!tracehook_notify_death(tsk, &noreap, &cookie) - && tsk->exit_signal != -1 && thread_group_empty(tsk)) - do_notify_parent(tsk, tsk->exit_signal); + + /* If something other than our normal parent is ptracing us, then + * send it a SIGCHLD instead of honoring exit_signal. exit_signal + * only has special meaning to our real parent. + */ + if (tsk->exit_signal != -1 && thread_group_empty(tsk)) { + int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD; + do_notify_parent(tsk, signal); + } else if (tsk->ptrace) { + do_notify_parent(tsk, SIGCHLD); + } state = EXIT_ZOMBIE; - if (tsk->exit_signal == -1 && !noreap) + if (tsk->exit_signal == -1 && + (likely(tsk->ptrace == 0) || + unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT))) state = EXIT_DEAD; tsk->exit_state = state; write_unlock_irq(&tasklist_lock); - tracehook_report_death(tsk, state, cookie); + list_for_each_safe(_p, _n, &ptrace_dead) { + list_del_init(_p); + t = list_entry(_p, struct task_struct, ptrace_list); + release_task(t); + } /* If the process is dead, release it - nobody will wait for it */ if (state == EXIT_DEAD) @@ -785,7 +868,10 @@ fastcall NORET_TYPE void do_exit(long code) if (unlikely(tsk == child_reaper)) panic("Attempted to kill init!"); - tracehook_report_exit(&code); + if (unlikely(current->ptrace & PT_TRACE_EXIT)) { + current->ptrace_message = code; + ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); + } /* * We're taking recursive faults here in do_exit. Safest is to just @@ -802,8 +888,6 @@ fastcall NORET_TYPE void do_exit(long code) tsk->flags |= PF_EXITING; - ptrace_exit(tsk); - if (unlikely(in_atomic())) printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", current->comm, current->pid, @@ -974,9 +1058,10 @@ static int eligible_child(pid_t pid, int options, struct task_struct *p) } /* - * Do not consider detached threads. + * Do not consider detached threads that are + * not ptraced: */ - if (p->exit_signal == -1) + if (p->exit_signal == -1 && !p->ptrace) return 0; /* Wait for all children (clone and not) if __WALL is set; @@ -1047,7 +1132,7 @@ static int wait_task_zombie(struct task_struct *p, int noreap, if (unlikely(p->exit_state != EXIT_ZOMBIE)) return 0; - if (unlikely(p->exit_signal == -1)) + if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) return 0; get_task_struct(p); read_unlock(&tasklist_lock); @@ -1071,9 +1156,15 @@ static int wait_task_zombie(struct task_struct *p, int noreap, BUG_ON(state != EXIT_DEAD); return 0; } - BUG_ON(p->exit_signal == -1); + if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) { + /* + * This can only happen in a race with a ptraced thread + * dying on another processor. + */ + return 0; + } - if (likely(p->signal)) { + if (likely(p->real_parent == p->parent) && likely(p->signal)) { struct signal_struct *psig; struct signal_struct *sig; @@ -1155,8 +1246,28 @@ static int wait_task_zombie(struct task_struct *p, int noreap, return retval; } retval = p->pid; - release_task(p); - + if (p->real_parent != p->parent) { + write_lock_irq(&tasklist_lock); + /* Double-check with lock held. */ + if (p->real_parent != p->parent) { + __ptrace_unlink(p); + // TODO: is this safe? + p->exit_state = EXIT_ZOMBIE; + /* + * If this is not a detached task, notify the parent. + * If it's still not detached after that, don't release + * it now. + */ + if (p->exit_signal != -1) { + do_notify_parent(p, p->exit_signal); + if (p->exit_signal != -1) + p = NULL; + } + } + write_unlock_irq(&tasklist_lock); + } + if (p != NULL) + release_task(p); BUG_ON(!retval); return retval; } @@ -1175,7 +1286,7 @@ static int wait_task_stopped(struct task_struct *p, int delayed_group_leader, if (!p->exit_code) return 0; - if (delayed_group_leader && + if (delayed_group_leader && !(p->ptrace & PT_PTRACED) && p->signal && p->signal->group_stop_count > 0) /* * A group stop is in progress and this is the group leader. @@ -1196,13 +1307,14 @@ static int wait_task_stopped(struct task_struct *p, int delayed_group_leader, if (unlikely(noreap)) { pid_t pid = p->pid; uid_t uid = p->uid; + int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED; exit_code = p->exit_code; if (unlikely(!exit_code) || unlikely(p->state & TASK_TRACED)) goto bail_ref; - return wait_noreap_copyout(p, pid, uid, CLD_STOPPED, - (exit_code << 8) | 0x7f, + return wait_noreap_copyout(p, pid, uid, + why, (exit_code << 8) | 0x7f, infop, ru); } @@ -1258,7 +1370,9 @@ bail_ref: if (!retval && infop) retval = put_user(0, &infop->si_errno); if (!retval && infop) - retval = put_user((short)CLD_STOPPED, &infop->si_code); + retval = put_user((short)((p->ptrace & PT_PTRACED) + ? CLD_TRAPPED : CLD_STOPPED), + &infop->si_code); if (!retval && infop) retval = put_user(exit_code, &infop->si_status); if (!retval && infop) @@ -1326,6 +1440,22 @@ static int wait_task_continued(struct task_struct *p, int noreap, } +static inline int my_ptrace_child(struct task_struct *p) +{ + if (!(p->ptrace & PT_PTRACED)) + return 0; + if (!(p->ptrace & PT_ATTACHED)) + return 1; + /* + * This child was PTRACE_ATTACH'd. We should be seeing it only if + * we are the attacher. If we are the real parent, this is a race + * inside ptrace_attach. It is waiting for the tasklist_lock, + * which we have to switch the parent links, but has already set + * the flags in p->ptrace. + */ + return (p->parent != p->real_parent); +} + static long do_wait(pid_t pid, int options, struct siginfo __user *infop, int __user *stat_addr, struct rusage __user *ru) { @@ -1357,17 +1487,26 @@ repeat: switch (p->state) { case TASK_TRACED: + /* + * When we hit the race with PTRACE_ATTACH, + * we will not report this child. But the + * race means it has not yet been moved to + * our ptrace_children list, so we need to + * set the flag here to avoid a spurious ECHILD + * when the race happens with the only child. + */ flag = 1; - continue; + if (!my_ptrace_child(p)) + continue; + /*FALLTHROUGH*/ case TASK_STOPPED: /* * It's stopped now, so it might later * continue, exit, or stop again. */ flag = 1; - if (!(options & WUNTRACED)) - continue; - if (tracehook_inhibit_wait_stopped(p)) + if (!(options & WUNTRACED) && + !my_ptrace_child(p)) continue; retval = wait_task_stopped(p, ret == 2, (options & WNOWAIT), @@ -1392,10 +1531,6 @@ repeat: goto check_continued; if (!likely(options & WEXITED)) continue; - if (tracehook_inhibit_wait_zombie(p)) { - flag = 1; - continue; - } retval = wait_task_zombie( p, (options & WNOWAIT), infop, stat_addr, ru); @@ -1412,8 +1547,6 @@ check_continued: flag = 1; if (!unlikely(options & WCONTINUED)) continue; - if (tracehook_inhibit_wait_continued(p)) - continue; retval = wait_task_continued( p, (options & WNOWAIT), infop, stat_addr, ru); @@ -1422,15 +1555,16 @@ check_continued: break; } } - - retval = ptrace_do_wait(tsk, pid, options, - infop, stat_addr, ru); - if (retval != -ECHILD) { - flag = 1; - if (retval != 0) /* He released the lock. */ - goto end; + if (!flag) { + list_for_each(_p, &tsk->ptrace_children) { + p = list_entry(_p, struct task_struct, + ptrace_list); + if (!eligible_child(pid, options, p)) + continue; + flag = 1; + break; + } } - if (options & __WNOTHREAD) break; tsk = next_thread(tsk); @@ -1454,7 +1588,7 @@ end: remove_wait_queue(¤t->signal->wait_chldexit,&wait); if (infop) { if (retval > 0) - retval = 0; + retval = 0; else { /* * For a WNOHANG return, clear out all the fields