X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fexit.c;h=c84802f4fd1bc811c9149e7033bbfd16c960a4c0;hb=f7f1b0f1e2fbadeab12d24236000e778aa9b1ead;hp=8c5742ebb904679546b825b47c74bba1ac92a769;hpb=9bf4aaab3e101692164d49b7ca357651eb691cb6;p=linux-2.6.git diff --git a/kernel/exit.c b/kernel/exit.c index 8c5742ebb..c84802f4f 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -14,7 +14,9 @@ #include #include #include +#include #include +#include #include #include #include @@ -23,7 +25,11 @@ #include #include #include +#include +#include +#include #include +#include #include #include @@ -35,13 +41,15 @@ extern struct task_struct *child_reaper; int getrusage(struct task_struct *, int, struct rusage __user *); +static void exit_mm(struct task_struct * tsk); + static void __unhash_process(struct task_struct *p) { nr_threads--; /* tasklist_lock is held, is this sufficient? */ if (p->vx_info) { - atomic_dec(&p->vx_info->cacct.nr_threads); - atomic_dec(&p->vx_info->limit.rcur[RLIMIT_NPROC]); + atomic_dec(&p->vx_info->cvirt.nr_threads); + vx_nproc_dec(p); } detach_pid(p, PIDTYPE_PID); detach_pid(p, PIDTYPE_TGID); @@ -62,8 +70,6 @@ void release_task(struct task_struct * p) struct dentry *proc_dentry; repeat: - BUG_ON(p->state < TASK_ZOMBIE); - atomic_dec(&p->user->processes); spin_lock(&p->proc_lock); proc_dentry = proc_pid_unhash(p); @@ -82,7 +88,7 @@ repeat: */ zap_leader = 0; leader = p->group_leader; - if (leader != p && thread_group_empty(leader) && leader->state == TASK_ZOMBIE) { + if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { BUG_ON(leader->exit_signal == -1); do_notify_parent(leader, leader->exit_signal); /* @@ -96,17 +102,15 @@ repeat: zap_leader = (leader->exit_signal == -1); } - p->parent->cutime += p->utime + p->cutime; - p->parent->cstime += p->stime + p->cstime; - p->parent->cmin_flt += p->min_flt + p->cmin_flt; - p->parent->cmaj_flt += p->maj_flt + p->cmaj_flt; - p->parent->cnvcsw += p->nvcsw + p->cnvcsw; - p->parent->cnivcsw += p->nivcsw + p->cnivcsw; sched_exit(p); write_unlock_irq(&tasklist_lock); spin_unlock(&p->proc_lock); proc_pid_flush(proc_dentry); release_thread(p); + if (p->vx_info) + release_vx_info(p->vx_info, p); + if (p->nx_info) + release_nx_info(p->nx_info, p); put_task_struct(p); p = leader; @@ -137,16 +141,15 @@ void unhash_process(struct task_struct *p) int session_of_pgrp(int pgrp) { struct task_struct *p; - struct list_head *l; - struct pid *pid; int sid = -1; read_lock(&tasklist_lock); - for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) + do_each_task_pid(pgrp, PIDTYPE_PGID, p) { if (p->signal->session > 0) { sid = p->signal->session; goto out; } + } while_each_task_pid(pgrp, PIDTYPE_PGID, p); p = find_task_by_pid(pgrp); if (p) sid = p->signal->session; @@ -167,13 +170,11 @@ out: static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task) { struct task_struct *p; - struct list_head *l; - struct pid *pid; int ret = 1; - for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) { + do_each_task_pid(pgrp, PIDTYPE_PGID, p) { if (p == ignored_task - || p->state >= TASK_ZOMBIE + || p->exit_state || p->real_parent->pid == 1) continue; if (process_group(p->real_parent) != pgrp @@ -181,7 +182,7 @@ static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task) ret = 0; break; } - } + } while_each_task_pid(pgrp, PIDTYPE_PGID, p); return ret; /* (sighing) "Often!" */ } @@ -200,10 +201,8 @@ static inline int has_stopped_jobs(int pgrp) { int retval = 0; struct task_struct *p; - struct list_head *l; - struct pid *pid; - for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) { + do_each_task_pid(pgrp, PIDTYPE_PGID, p) { if (p->state != TASK_STOPPED) continue; @@ -219,12 +218,12 @@ static inline int has_stopped_jobs(int pgrp) retval = 1; break; - } + } while_each_task_pid(pgrp, PIDTYPE_PGID, p); return retval; } /** - * reparent_to_init() - Reparent the calling kernel thread to the init task. + * reparent_to_init - Reparent the calling kernel thread to the init task. * * If a kernel thread is launched as a result of a system call, or if * it ever exits, it should generally reparent itself to init so that @@ -235,7 +234,7 @@ static inline int has_stopped_jobs(int pgrp) * * NOTE that reparent_to_init() gives the caller full capabilities. */ -void reparent_to_init(void) +static inline void reparent_to_init(void) { write_lock_irq(&tasklist_lock); @@ -256,11 +255,11 @@ void reparent_to_init(void) /* rt_priority? */ /* signals? */ security_task_reparent_to_init(current); - memcpy(current->rlim, init_task.rlim, sizeof(*(current->rlim))); + memcpy(current->signal->rlim, init_task.signal->rlim, + sizeof(current->signal->rlim)); atomic_inc(&(INIT_USER->__count)); - switch_uid(INIT_USER); - write_unlock_irq(&tasklist_lock); + switch_uid(INIT_USER); } void __set_special_pids(pid_t session, pid_t pgrp) @@ -293,7 +292,7 @@ void set_special_pids(pid_t session, pid_t pgrp) */ int allow_signal(int sig) { - if (sig < 1 || sig > _NSIG) + if (!valid_signal(sig) || sig < 1) return -EINVAL; spin_lock_irq(¤t->sighand->siglock); @@ -314,7 +313,7 @@ EXPORT_SYMBOL(allow_signal); int disallow_signal(int sig) { - if (sig < 1 || sig > _NSIG) + if (!valid_signal(sig) || sig < 1) return -EINVAL; spin_lock_irq(¤t->sighand->siglock); @@ -349,7 +348,9 @@ void daemonize(const char *name, ...) exit_mm(current); set_special_pids(1, 1); + down(&tty_sem); current->signal->tty = NULL; + up(&tty_sem); /* Block and flush all signals */ sigfillset(&blocked); @@ -387,7 +388,7 @@ static inline void close_files(struct files_struct * files) struct file * file = xchg(&files->fd[i], NULL); if (file) filp_close(file, files); - // vx_openfd_dec(i); + vx_openfd_dec(i); } i++; set >>= 1; @@ -488,7 +489,7 @@ EXPORT_SYMBOL_GPL(exit_fs); * Turn us into a lazy TLB process if we * aren't already.. */ -static inline void __exit_mm(struct task_struct * tsk) +static void exit_mm(struct task_struct * tsk) { struct mm_struct *mm = tsk->mm; @@ -524,25 +525,14 @@ static inline void __exit_mm(struct task_struct * tsk) mmput(mm); } -void exit_mm(struct task_struct *tsk) -{ - __exit_mm(tsk); -} - -EXPORT_SYMBOL(exit_mm); - static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper) { /* * Make sure we're not reparenting to ourselves and that * the parent is not a zombie. */ - if (p == reaper || reaper->state >= TASK_ZOMBIE) - p->real_parent = child_reaper; - else - p->real_parent = reaper; - if (p->parent == p->real_parent) - BUG(); + BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE); + p->real_parent = reaper; } static inline void reparent_thread(task_t *p, task_t *father, int traced) @@ -550,7 +540,6 @@ static inline void reparent_thread(task_t *p, task_t *father, int traced) /* We don't want people slaying init. */ if (p->exit_signal != -1) p->exit_signal = SIGCHLD; - p->self_exec_id++; if (p->pdeath_signal) /* We already hold the tasklist_lock here. */ @@ -574,9 +563,17 @@ static inline void reparent_thread(task_t *p, task_t *father, int traced) /* If we'd notified the old parent about this child's death, * also notify the new parent. */ - if (p->state == TASK_ZOMBIE && p->exit_signal != -1 && + 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); + } } /* @@ -609,9 +606,13 @@ static inline void forget_original_parent(struct task_struct * father, struct list_head *_p, *_n; /* FIXME handle vchild_reaper/initpid */ - reaper = father->group_leader; - if (reaper == father) - reaper = child_reaper; + do { + reaper = next_thread(reaper); + if (reaper == father) { + reaper = child_reaper; + break; + } + } while (reaper->exit_state); /* * There are only two places where our children can be: @@ -637,7 +638,7 @@ static inline void forget_original_parent(struct task_struct * father, } else { /* reparent ptraced task to its real parent */ __ptrace_unlink (p); - if (p->state == TASK_ZOMBIE && p->exit_signal != -1 && + if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 && thread_group_empty(p)) do_notify_parent(p, p->exit_signal); } @@ -648,7 +649,7 @@ static inline void forget_original_parent(struct task_struct * father, * 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->state == TASK_ZOMBIE && p->exit_signal == -1)) + 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) { @@ -668,7 +669,7 @@ static void exit_notify(struct task_struct *tsk) struct task_struct *t; struct list_head ptrace_dead, *_p, *_n; - if (signal_pending(tsk) && !tsk->signal->group_exit + if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT) && !thread_group_empty(tsk)) { /* * This occurs when there was a race between our exit @@ -761,34 +762,14 @@ static void exit_notify(struct task_struct *tsk) do_notify_parent(tsk, SIGCHLD); } - state = TASK_ZOMBIE; - if (tsk->exit_signal == -1 && tsk->ptrace == 0) - state = TASK_DEAD; - tsk->state = state; - tsk->flags |= PF_DEAD; - - /* - * Clear these here so that update_process_times() won't try to deliver - * itimer, profile or rlimit signals to this task while it is in late exit. - */ - tsk->it_virt_value = 0; - tsk->it_prof_value = 0; - tsk->rlim[RLIMIT_CPU].rlim_cur = RLIM_INFINITY; + state = EXIT_ZOMBIE; + if (tsk->exit_signal == -1 && + (likely(tsk->ptrace == 0) || + unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT))) + state = EXIT_DEAD; + tsk->exit_state = state; - /* - * In the preemption case it must be impossible for the task - * to get runnable again, so use "_raw_" unlock to keep - * preempt_count elevated until we schedule(). - * - * To avoid deadlock on SMP, interrupts must be unmasked. If we - * don't, subsequently called functions (e.g, wait_task_inactive() - * via release_task()) will spin, with interrupt flags - * unwittingly blocked, until the other task sleeps. That task - * may itself be waiting for smp_call_function() to answer and - * complete, and with interrupts blocked that will never happen. - */ - _raw_write_unlock(&tasklist_lock); - local_irq_enable(); + write_unlock_irq(&tasklist_lock); list_for_each_safe(_p, _n, &ptrace_dead) { list_del_init(_p); @@ -797,14 +778,20 @@ static void exit_notify(struct task_struct *tsk) } /* If the process is dead, release it - nobody will wait for it */ - if (state == TASK_DEAD) + if (state == EXIT_DEAD) release_task(tsk); + /* PF_DEAD causes final put_task_struct after we schedule. */ + preempt_disable(); + tsk->flags |= PF_DEAD; } -asmlinkage NORET_TYPE void do_exit(long code) +fastcall NORET_TYPE void do_exit(long code) { struct task_struct *tsk = current; + int group_dead; + + profile_task_exit(tsk); if (unlikely(in_interrupt())) panic("Aiee, killing interrupt handler!"); @@ -814,31 +801,43 @@ asmlinkage NORET_TYPE void do_exit(long code) panic("Attempted to kill init!"); if (tsk->io_context) exit_io_context(); + + if (unlikely(current->ptrace & PT_TRACE_EXIT)) { + current->ptrace_message = code; + ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); + } + tsk->flags |= PF_EXITING; - del_timer_sync(&tsk->real_timer); + + /* + * Make sure we don't try to process any timer firings + * while we are already exiting. + */ + tsk->it_virt_expires = cputime_zero; + tsk->it_prof_expires = cputime_zero; + tsk->it_sched_expires = 0; if (unlikely(in_atomic())) printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", current->comm, current->pid, preempt_count()); - profile_exit_task(tsk); - - if (unlikely(current->ptrace & PT_TRACE_EXIT)) { - current->ptrace_message = code; - ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP); - } - - acct_process(code); - __exit_mm(tsk); + acct_update_integrals(tsk); + update_mem_hiwater(tsk); + group_dead = atomic_dec_and_test(&tsk->signal->live); + if (group_dead) + acct_process(code); + exit_mm(tsk); exit_sem(tsk); __exit_files(tsk); __exit_fs(tsk); exit_namespace(tsk); exit_thread(); + cpuset_exit(tsk); + exit_keys(tsk); - if (tsk->signal->leader) + if (group_dead && tsk->signal->leader) disassociate_ctty(1); module_put(tsk->thread_info->exec_domain->module); @@ -851,12 +850,16 @@ asmlinkage NORET_TYPE void do_exit(long code) mpol_free(tsk->mempolicy); tsk->mempolicy = NULL; #endif + + BUG_ON(!(current->flags & PF_DEAD)); schedule(); BUG(); /* Avoid "noreturn function does return". */ for (;;) ; } +EXPORT_SYMBOL_GPL(do_exit); + NORET_TYPE void complete_and_exit(struct completion *comp, long code) { if (comp) @@ -874,21 +877,7 @@ asmlinkage long sys_exit(int error_code) task_t fastcall *next_thread(const task_t *p) { - const struct pid_link *link = p->pids + PIDTYPE_TGID; - const struct list_head *tmp, *head = &link->pidptr->task_list; - -#ifdef CONFIG_SMP - if (!p->sighand) - BUG(); - if (!spin_is_locked(&p->sighand->siglock) && - !rwlock_is_locked(&tasklist_lock)) - BUG(); -#endif - tmp = link->pid_chain.next; - if (tmp == head) - tmp = head->next; - - return pid_task(tmp, PIDTYPE_TGID); + return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID); } EXPORT_SYMBOL(next_thread); @@ -902,18 +891,18 @@ do_group_exit(int exit_code) { BUG_ON(exit_code & 0x80); /* core dumps don't get here */ - if (current->signal->group_exit) + if (current->signal->flags & SIGNAL_GROUP_EXIT) exit_code = current->signal->group_exit_code; else if (!thread_group_empty(current)) { struct signal_struct *const sig = current->signal; struct sighand_struct *const sighand = current->sighand; read_lock(&tasklist_lock); spin_lock_irq(&sighand->siglock); - if (sig->group_exit) + if (sig->flags & SIGNAL_GROUP_EXIT) /* Another thread got here before we took the lock. */ exit_code = sig->group_exit_code; else { - sig->group_exit = 1; + sig->flags = SIGNAL_GROUP_EXIT; sig->group_exit_code = exit_code; zap_other_threads(current); } @@ -976,48 +965,158 @@ static int eligible_child(pid_t pid, int options, task_t *p) return 1; } +static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid, + int why, int status, + struct siginfo __user *infop, + struct rusage __user *rusagep) +{ + int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0; + put_task_struct(p); + if (!retval) + retval = put_user(SIGCHLD, &infop->si_signo); + if (!retval) + retval = put_user(0, &infop->si_errno); + if (!retval) + retval = put_user((short)why, &infop->si_code); + if (!retval) + retval = put_user(pid, &infop->si_pid); + if (!retval) + retval = put_user(uid, &infop->si_uid); + if (!retval) + retval = put_user(status, &infop->si_status); + if (!retval) + retval = pid; + return retval; +} + /* - * Handle sys_wait4 work for one task in state TASK_ZOMBIE. We hold + * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold * read_lock(&tasklist_lock) on entry. If we return zero, we still hold * the lock and this task is uninteresting. If we return nonzero, we have * released the lock and the system call should return. */ -static int wait_task_zombie(task_t *p, unsigned int __user *stat_addr, struct rusage __user *ru) +static int wait_task_zombie(task_t *p, int noreap, + struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) { unsigned long state; int retval; + int status; + + if (unlikely(noreap)) { + pid_t pid = p->pid; + uid_t uid = p->uid; + int exit_code = p->exit_code; + int why, status; + + if (unlikely(p->exit_state != EXIT_ZOMBIE)) + return 0; + if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) + return 0; + get_task_struct(p); + read_unlock(&tasklist_lock); + if ((exit_code & 0x7f) == 0) { + why = CLD_EXITED; + status = exit_code >> 8; + } else { + why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED; + status = exit_code & 0x7f; + } + return wait_noreap_copyout(p, pid, uid, why, + status, infop, ru); + } /* * Try to move the task's state to DEAD * only one thread is allowed to do this: */ - state = xchg(&p->state, TASK_DEAD); - if (state != TASK_ZOMBIE) { - BUG_ON(state != TASK_DEAD); + state = xchg(&p->exit_state, EXIT_DEAD); + if (state != EXIT_ZOMBIE) { + BUG_ON(state != EXIT_DEAD); return 0; } - if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) + 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->real_parent == p->parent) && likely(p->signal)) { + /* + * The resource counters for the group leader are in its + * own task_struct. Those for dead threads in the group + * are in its signal_struct, as are those for the child + * processes it has previously reaped. All these + * accumulate in the parent's signal_struct c* fields. + * + * We don't bother to take a lock here to protect these + * p->signal fields, because they are only touched by + * __exit_signal, which runs with tasklist_lock + * write-locked anyway, and so is excluded here. We do + * need to protect the access to p->parent->signal fields, + * as other threads in the parent group can be right + * here reaping other children at the same time. + */ + spin_lock_irq(&p->parent->sighand->siglock); + p->parent->signal->cutime = + cputime_add(p->parent->signal->cutime, + cputime_add(p->utime, + cputime_add(p->signal->utime, + p->signal->cutime))); + p->parent->signal->cstime = + cputime_add(p->parent->signal->cstime, + cputime_add(p->stime, + cputime_add(p->signal->stime, + p->signal->cstime))); + p->parent->signal->cmin_flt += + p->min_flt + p->signal->min_flt + p->signal->cmin_flt; + p->parent->signal->cmaj_flt += + p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt; + p->parent->signal->cnvcsw += + p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw; + p->parent->signal->cnivcsw += + p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw; + spin_unlock_irq(&p->parent->sighand->siglock); + } /* * Now we are sure this task is interesting, and no other - * thread can reap it because we set its state to TASK_DEAD. + * thread can reap it because we set its state to EXIT_DEAD. */ read_unlock(&tasklist_lock); retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; - if (!retval && stat_addr) { - if (p->signal->group_exit) - retval = put_user(p->signal->group_exit_code, stat_addr); - else - retval = put_user(p->exit_code, stat_addr); + status = (p->signal->flags & SIGNAL_GROUP_EXIT) + ? p->signal->group_exit_code : p->exit_code; + if (!retval && stat_addr) + retval = put_user(status, stat_addr); + if (!retval && infop) + retval = put_user(SIGCHLD, &infop->si_signo); + if (!retval && infop) + retval = put_user(0, &infop->si_errno); + if (!retval && infop) { + int why; + + if ((status & 0x7f) == 0) { + why = CLD_EXITED; + status >>= 8; + } else { + why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; + status &= 0x7f; + } + retval = put_user((short)why, &infop->si_code); + if (!retval) + retval = put_user(status, &infop->si_status); } + if (!retval && infop) + retval = put_user(p->pid, &infop->si_pid); + if (!retval && infop) + retval = put_user(p->uid, &infop->si_uid); if (retval) { - p->state = TASK_ZOMBIE; + // TODO: is this safe? + p->exit_state = EXIT_ZOMBIE; return retval; } retval = p->pid; @@ -1026,10 +1125,12 @@ static int wait_task_zombie(task_t *p, unsigned int __user *stat_addr, struct ru /* Double-check with lock held. */ if (p->real_parent != p->parent) { __ptrace_unlink(p); - p->state = TASK_ZOMBIE; + // 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 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); @@ -1051,9 +1152,9 @@ static int wait_task_zombie(task_t *p, unsigned int __user *stat_addr, struct ru * the lock and this task is uninteresting. If we return nonzero, we have * released the lock and the system call should return. */ -static int wait_task_stopped(task_t *p, int delayed_group_leader, - unsigned int __user *stat_addr, - struct rusage __user *ru) +static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap, + struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) { int retval, exit_code; @@ -1076,18 +1177,33 @@ static int wait_task_stopped(task_t *p, int delayed_group_leader, */ get_task_struct(p); read_unlock(&tasklist_lock); + + 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_STOPPED)) + goto bail_ref; + return wait_noreap_copyout(p, pid, uid, + why, (exit_code << 8) | 0x7f, + infop, ru); + } + write_lock_irq(&tasklist_lock); /* * This uses xchg to be atomic with the thread resuming and setting * it. It must also be done with the write lock held to prevent a - * race with the TASK_ZOMBIE case. + * race with the EXIT_ZOMBIE case. */ exit_code = xchg(&p->exit_code, 0); - if (unlikely(p->state > TASK_STOPPED)) { + if (unlikely(p->exit_state)) { /* * The task resumed and then died. Let the next iteration - * catch it in TASK_ZOMBIE. Note that exit_code might + * catch it in EXIT_ZOMBIE. Note that exit_code might * already be zero here if it resumed and did _exit(0). * The task itself is dead and won't touch exit_code again; * other processors in this function are locked out. @@ -1101,9 +1217,17 @@ static int wait_task_stopped(task_t *p, int delayed_group_leader, * resumed, or it resumed and then died. */ write_unlock_irq(&tasklist_lock); +bail_ref: put_task_struct(p); - read_lock(&tasklist_lock); - return 0; + /* + * We are returning to the wait loop without having successfully + * removed the process and having released the lock. We cannot + * continue, since the "p" task pointer is potentially stale. + * + * Return -EAGAIN, and do_wait() will restart the loop from the + * beginning. Do _not_ re-acquire the lock. + */ + return -EAGAIN; } /* move to end of parent's list to avoid starvation */ @@ -1115,6 +1239,20 @@ static int wait_task_stopped(task_t *p, int delayed_group_leader, retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; if (!retval && stat_addr) retval = put_user((exit_code << 8) | 0x7f, stat_addr); + if (!retval && infop) + retval = put_user(SIGCHLD, &infop->si_signo); + if (!retval && infop) + retval = put_user(0, &infop->si_errno); + if (!retval && infop) + 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) + retval = put_user(p->pid, &infop->si_pid); + if (!retval && infop) + retval = put_user(p->uid, &infop->si_uid); if (!retval) retval = p->pid; put_task_struct(p); @@ -1123,17 +1261,88 @@ static int wait_task_stopped(task_t *p, int delayed_group_leader, return retval; } -asmlinkage long sys_wait4(pid_t pid,unsigned int __user *stat_addr, int options, struct rusage __user *ru) +/* + * Handle do_wait work for one task in a live, non-stopped state. + * read_lock(&tasklist_lock) on entry. If we return zero, we still hold + * the lock and this task is uninteresting. If we return nonzero, we have + * released the lock and the system call should return. + */ +static int wait_task_continued(task_t *p, int noreap, + struct siginfo __user *infop, + int __user *stat_addr, struct rusage __user *ru) +{ + int retval; + pid_t pid; + uid_t uid; + + if (unlikely(!p->signal)) + return 0; + + if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) + return 0; + + spin_lock_irq(&p->sighand->siglock); + /* Re-check with the lock held. */ + if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { + spin_unlock_irq(&p->sighand->siglock); + return 0; + } + if (!noreap) + p->signal->flags &= ~SIGNAL_STOP_CONTINUED; + spin_unlock_irq(&p->sighand->siglock); + + pid = p->pid; + uid = p->uid; + get_task_struct(p); + read_unlock(&tasklist_lock); + + if (!infop) { + retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0; + put_task_struct(p); + if (!retval && stat_addr) + retval = put_user(0xffff, stat_addr); + if (!retval) + retval = p->pid; + } else { + retval = wait_noreap_copyout(p, pid, uid, + CLD_CONTINUED, SIGCONT, + infop, ru); + BUG_ON(retval == 0); + } + + return retval; +} + + +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) { DECLARE_WAITQUEUE(wait, current); struct task_struct *tsk; int flag, retval; - if (options & ~(WNOHANG|WUNTRACED|__WNOTHREAD|__WCLONE|__WALL)) - return -EINVAL; - - add_wait_queue(¤t->wait_chldexit,&wait); + add_wait_queue(¤t->signal->wait_chldexit,&wait); repeat: + /* + * We will set this flag if we see any child that might later + * match our criteria, even if we are not able to reap it yet. + */ flag = 0; current->state = TASK_INTERRUPTIBLE; read_lock(&tasklist_lock); @@ -1149,33 +1358,72 @@ repeat: ret = eligible_child(pid, options, p); if (!ret) continue; - flag = 1; switch (p->state) { + case TASK_TRACED: + 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) && - !(p->ptrace & PT_PTRACED)) + !my_ptrace_child(p)) continue; retval = wait_task_stopped(p, ret == 2, + (options & WNOWAIT), + infop, stat_addr, ru); + if (retval == -EAGAIN) + goto repeat; if (retval != 0) /* He released the lock. */ - goto end_wait4; + goto end; break; - case TASK_ZOMBIE: + default: + // case EXIT_DEAD: + if (p->exit_state == EXIT_DEAD) + continue; + // case EXIT_ZOMBIE: + if (p->exit_state == EXIT_ZOMBIE) { + /* + * Eligible but we cannot release + * it yet: + */ + if (ret == 2) + goto check_continued; + if (!likely(options & WEXITED)) + continue; + retval = wait_task_zombie( + p, (options & WNOWAIT), + infop, stat_addr, ru); + /* He released the lock. */ + if (retval != 0) + goto end; + break; + } +check_continued: /* - * Eligible but we cannot release it yet: + * It's running now, so it might later + * exit, stop, or stop and then continue. */ - if (ret == 2) + flag = 1; + if (!unlikely(options & WCONTINUED)) continue; - retval = wait_task_zombie(p, stat_addr, ru); + retval = wait_task_continued( + p, (options & WNOWAIT), + infop, stat_addr, ru); if (retval != 0) /* He released the lock. */ - goto end_wait4; + goto end; break; } } if (!flag) { - list_for_each (_p,&tsk->ptrace_children) { - p = list_entry(_p,struct task_struct,ptrace_list); + 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; @@ -1188,31 +1436,105 @@ repeat: if (tsk->signal != current->signal) BUG(); } while (tsk != current); + read_unlock(&tasklist_lock); if (flag) { retval = 0; if (options & WNOHANG) - goto end_wait4; + goto end; retval = -ERESTARTSYS; if (signal_pending(current)) - goto end_wait4; + goto end; schedule(); goto repeat; } retval = -ECHILD; -end_wait4: +end: current->state = TASK_RUNNING; - remove_wait_queue(¤t->wait_chldexit,&wait); + remove_wait_queue(¤t->signal->wait_chldexit,&wait); + if (infop) { + if (retval > 0) + retval = 0; + else { + /* + * For a WNOHANG return, clear out all the fields + * we would set so the user can easily tell the + * difference. + */ + if (!retval) + retval = put_user(0, &infop->si_signo); + if (!retval) + retval = put_user(0, &infop->si_errno); + if (!retval) + retval = put_user(0, &infop->si_code); + if (!retval) + retval = put_user(0, &infop->si_pid); + if (!retval) + retval = put_user(0, &infop->si_uid); + if (!retval) + retval = put_user(0, &infop->si_status); + } + } return retval; } +asmlinkage long sys_waitid(int which, pid_t pid, + struct siginfo __user *infop, int options, + struct rusage __user *ru) +{ + long ret; + + if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED)) + return -EINVAL; + if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) + return -EINVAL; + + switch (which) { + case P_ALL: + pid = -1; + break; + case P_PID: + if (pid <= 0) + return -EINVAL; + break; + case P_PGID: + if (pid <= 0) + return -EINVAL; + pid = -pid; + break; + default: + return -EINVAL; + } + + ret = do_wait(pid, options, infop, NULL, ru); + + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; +} + +asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr, + int options, struct rusage __user *ru) +{ + long ret; + + if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| + __WNOTHREAD|__WCLONE|__WALL)) + return -EINVAL; + ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru); + + /* avoid REGPARM breakage on x86: */ + prevent_tail_call(ret); + return ret; +} + #ifdef __ARCH_WANT_SYS_WAITPID /* * sys_waitpid() remains for compatibility. waitpid() should be * implemented by calling sys_wait4() from libc.a. */ -asmlinkage long sys_waitpid(pid_t pid, unsigned __user *stat_addr, int options) +asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options) { return sys_wait4(pid, stat_addr, options, NULL); }