This commit was manufactured by cvs2svn to create tag
[linux-2.6.git] / kernel / exit.c
index 2b2f728..764c1ad 100644 (file)
@@ -14,7 +14,9 @@
 #include <linux/personality.h>
 #include <linux/tty.h>
 #include <linux/namespace.h>
+#include <linux/key.h>
 #include <linux/security.h>
+#include <linux/cpu.h>
 #include <linux/acct.h>
 #include <linux/file.h>
 #include <linux/binfmts.h>
 #include <linux/mount.h>
 #include <linux/proc_fs.h>
 #include <linux/mempolicy.h>
+#include <linux/ckrm.h>
+#include <linux/ckrm_tsk.h>
+#include <linux/vs_limit.h>
+#include <linux/ckrm_mem.h>
+#include <linux/syscalls.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -37,6 +44,11 @@ int getrusage(struct task_struct *, int, struct rusage __user *);
 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->cvirt.nr_threads);
+               vx_nproc_dec(p);
+       }
        detach_pid(p, PIDTYPE_PID);
        detach_pid(p, PIDTYPE_TGID);
        if (thread_group_leader(p)) {
@@ -56,8 +68,6 @@ 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);
@@ -76,7 +86,7 @@ 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);
                /*
@@ -90,12 +100,6 @@ 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);
@@ -131,16 +135,15 @@ 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;
@@ -161,13 +164,11 @@ 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 >= EXIT_ZOMBIE
                                || p->real_parent->pid == 1)
                        continue;
                if (process_group(p->real_parent) != pgrp
@@ -175,7 +176,7 @@ 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!" */
 }
 
@@ -194,10 +195,8 @@ 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;
 
@@ -213,7 +212,7 @@ static inline int has_stopped_jobs(int pgrp)
 
                retval = 1;
                break;
-       }
+       } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
        return retval;
 }
 
@@ -236,6 +235,7 @@ void reparent_to_init(void)
        ptrace_unlink(current);
        /* Reparent to init */
        REMOVE_LINKS(current);
+       /* FIXME handle vchild_reaper/initpid */
        current->parent = child_reaper;
        current->real_parent = child_reaper;
        SET_LINKS(current);
@@ -249,11 +249,11 @@ 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)
@@ -342,7 +342,9 @@ 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);
@@ -378,7 +380,7 @@ static inline void close_files(struct files_struct * files)
                while (set) {
                        if (set & 1) {
                                struct file * file = xchg(&files->fd[i], NULL);
-                               if (file)
+                               if (file) 
                                        filp_close(file, files);
                        }
                        i++;
@@ -511,6 +513,12 @@ static inline void __exit_mm(struct task_struct * tsk)
        task_lock(tsk);
        tsk->mm = NULL;
        up_read(&mm->mmap_sem);
+#ifdef CONFIG_CKRM_RES_MEM
+       spin_lock(&mm->peertask_lock);
+       list_del_init(&tsk->mm_peers);
+       ckrm_mem_evaluate_mm(mm);
+       spin_unlock(&mm->peertask_lock);
+#endif
        enter_lazy_tlb(mm, current);
        task_unlock(tsk);
        mmput(mm);
@@ -521,18 +529,14 @@ 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;
+       BUG_ON(p == reaper || reaper->state >= EXIT_ZOMBIE || reaper->exit_state >= EXIT_ZOMBIE);
+       p->real_parent = reaper;
        if (p->parent == p->real_parent)
                BUG();
 }
@@ -542,7 +546,6 @@ 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.  */
@@ -566,9 +569,17 @@ 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);
+               }
        }
 
        /*
@@ -600,9 +611,13 @@ static inline void forget_original_parent(struct task_struct * father,
        struct task_struct *p, *reaper = father;
        struct list_head *_p, *_n;
 
-       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 >= EXIT_ZOMBIE);
 
        /*
         * There are only two places where our children can be:
@@ -628,7 +643,7 @@ 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);
                }
@@ -639,7 +654,7 @@ 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) {
@@ -659,6 +674,8 @@ static void exit_notify(struct task_struct *tsk)
        struct task_struct *t;
        struct list_head ptrace_dead, *_p, *_n;
 
+       ckrm_cb_exit(tsk);
+
        if (signal_pending(tsk) && !tsk->signal->group_exit
            && !thread_group_empty(tsk)) {
                /*
@@ -752,11 +769,10 @@ static void exit_notify(struct task_struct *tsk)
                do_notify_parent(tsk, SIGCHLD);
        }
 
-       state = TASK_ZOMBIE;
+       state = EXIT_ZOMBIE;
        if (tsk->exit_signal == -1 && tsk->ptrace == 0)
-               state = TASK_DEAD;
-       tsk->state = state;
-       tsk->flags |= PF_DEAD;
+               state = EXIT_DEAD;
+       tsk->exit_state = state;
 
        /*
         * Clear these here so that update_process_times() won't try to deliver
@@ -764,22 +780,8 @@ static void exit_notify(struct task_struct *tsk)
         */
        tsk->it_virt_value = 0;
        tsk->it_prof_value = 0;
-       tsk->rlim[RLIMIT_CPU].rlim_cur = RLIM_INFINITY;
 
-       /*
-        * 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);
@@ -788,14 +790,20 @@ 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!");
@@ -813,14 +821,21 @@ asmlinkage NORET_TYPE void do_exit(long code)
                                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);
+       group_dead = atomic_dec_and_test(&tsk->signal->live);
+       if (group_dead)
+               acct_process(code);
+       if (current->tux_info) {
+#ifdef CONFIG_TUX_DEBUG
+               printk("Possibly unexpected TUX-thread exit(%ld) at %p?\n",
+                       code, __builtin_return_address(0));
+#endif
+               current->tux_exit();
+       }
        __exit_mm(tsk);
 
        exit_sem(tsk);
@@ -828,8 +843,9 @@ asmlinkage NORET_TYPE void do_exit(long code)
        __exit_fs(tsk);
        exit_namespace(tsk);
        exit_thread();
+       exit_keys(tsk);
 
-       if (tsk->signal->leader)
+       if (group_dead && tsk->signal->leader)
                disassociate_ctty(1);
 
        module_put(tsk->thread_info->exec_domain->module);
@@ -842,6 +858,8 @@ 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".  */
@@ -865,9 +883,6 @@ 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();
@@ -875,11 +890,7 @@ task_t fastcall *next_thread(const task_t *p)
                                !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);
@@ -967,48 +978,152 @@ 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 +=
+                       p->utime + p->signal->utime + p->signal->cutime;
+               p->parent->signal->cstime +=
+                       p->stime + 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->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;
@@ -1017,10 +1132,12 @@ 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);
@@ -1042,9 +1159,9 @@ 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;
 
@@ -1067,18 +1184,33 @@ 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 >= EXIT_ZOMBIE)) {
                /*
                 * 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.
@@ -1092,9 +1224,17 @@ 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 */
@@ -1106,6 +1246,20 @@ 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);
@@ -1114,17 +1268,87 @@ 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->stop_state >= 0)
+               return 0;
+
+       spin_lock_irq(&p->sighand->siglock);
+       if (p->signal->stop_state >= 0) { /* Re-check with the lock held.  */
+               spin_unlock_irq(&p->sighand->siglock);
+               return 0;
+       }
+       if (!noreap)
+               p->signal->stop_state = 0;
+       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(&current->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);
@@ -1140,33 +1364,73 @@ 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;
@@ -1179,31 +1443,105 @@ 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(&current->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);
 }