Merge branch 'linus' into xen-64bit

10 files changed, 442 insertions, 292 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 0a7ed838984b..985ddb7da4d0 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -11,8 +11,6 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
             hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
             notifier.o ksysfs.o pm_qos_params.o sched_clock.o
 
-CFLAGS_REMOVE_sched.o = -mno-spe
-
 ifdef CONFIG_FTRACE
 # Do not trace debug files and internal ftrace files
 CFLAGS_REMOVE_lockdep.o = -pg
@@ -21,6 +19,7 @@ CFLAGS_REMOVE_mutex-debug.o = -pg
 CFLAGS_REMOVE_rtmutex-debug.o = -pg
 CFLAGS_REMOVE_cgroup-debug.o = -pg
 CFLAGS_REMOVE_sched_clock.o = -pg
+CFLAGS_REMOVE_sched.o = -mno-spe -pg
 endif
 
 obj-$(CONFIG_SYSCTL_SYSCALL_CHECK) += sysctl_check.o
diff --git a/kernel/cpu.c b/kernel/cpu.c
index b11f06dc149a..cfb1d43ab801 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -299,6 +299,7 @@ int __ref cpu_down(unsigned int cpu)
         cpu_maps_update_done();
         return err;
 }
+EXPORT_SYMBOL(cpu_down);
 #endif /*CONFIG_HOTPLUG_CPU*/
 
 /* Requires cpu_add_remove_lock to be held */
diff --git a/kernel/exit.c b/kernel/exit.c
index ceb258782835..93d2711b9381 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -71,7 +71,7 @@ static void __unhash_process(struct task_struct *p)
                 __get_cpu_var(process_counts)--;
         }
         list_del_rcu(&p->thread_group);
-        remove_parent(p);
+        list_del_init(&p->sibling);
 }
 
 /*
@@ -152,6 +152,18 @@ static void delayed_put_task_struct(struct rcu_head *rhp)
         put_task_struct(container_of(rhp, struct task_struct, rcu));
 }
 
+/*
+ * Do final ptrace-related cleanup of a zombie being reaped.
+ *
+ * Called with write_lock(&tasklist_lock) held.
+ */
+static void ptrace_release_task(struct task_struct *p)
+{
+        BUG_ON(!list_empty(&p->ptraced));
+        ptrace_unlink(p);
+        BUG_ON(!list_empty(&p->ptrace_entry));
+}
+
 void release_task(struct task_struct * p)
 {
         struct task_struct *leader;
@@ -160,8 +172,7 @@ repeat:
         atomic_dec(&p->user->processes);
         proc_flush_task(p);
         write_lock_irq(&tasklist_lock);
-        ptrace_unlink(p);
-        BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
+        ptrace_release_task(p);
         __exit_signal(p);
 
         /*
@@ -315,9 +326,8 @@ static void reparent_to_kthreadd(void)
 
         ptrace_unlink(current);
         /* Reparent to init */
-        remove_parent(current);
         current->real_parent = current->parent = kthreadd_task;
-        add_parent(current);
+        list_move_tail(&current->sibling, &current->real_parent->children);
 
         /* Set the exit signal to SIGCHLD so we signal init on exit */
         current->exit_signal = SIGCHLD;
@@ -692,37 +702,97 @@ static void exit_mm(struct task_struct * tsk)
         mmput(mm);
 }
 
-static void
-reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
+/*
+ * Return nonzero if @parent's children should reap themselves.
+ *
+ * Called with write_lock_irq(&tasklist_lock) held.
+ */
+static int ignoring_children(struct task_struct *parent)
 {
-        if (p->pdeath_signal)
-                /* We already hold the tasklist_lock here.  */
-                group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
+        int ret;
+        struct sighand_struct *psig = parent->sighand;
+        unsigned long flags;
+        spin_lock_irqsave(&psig->siglock, flags);
+        ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
+               (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT));
+        spin_unlock_irqrestore(&psig->siglock, flags);
+        return ret;
+}
 
-        /* Move the child from its dying parent to the new one.  */
-        if (unlikely(traced)) {
-                /* Preserve ptrace links if someone else is tracing this child.  */
-                list_del_init(&p->ptrace_list);
-                if (ptrace_reparented(p))
-                        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.
+/*
+ * Detach all tasks we were using ptrace on.
+ * Any that need to be release_task'd are put on the @dead list.
+ *
+ * Called with write_lock(&tasklist_lock) held.
+ */
+static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
+{
+        struct task_struct *p, *n;
+        int ign = -1;
+
+        list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
+                __ptrace_unlink(p);
+
+                if (p->exit_state != EXIT_ZOMBIE)
+                        continue;
+
+                /*
+                 * If it's a zombie, our attachedness prevented normal
+                 * parent notification or self-reaping.  Do notification
+                 * now if it would have happened earlier.  If it should
+                 * reap itself, add it to the @dead list.  We can't call
+                 * release_task() here because we already hold tasklist_lock.
+                 *
+                 * If it's our own child, there is no notification to do.
+                 * But if our normal children self-reap, then this child
+                 * was prevented by ptrace and we must reap it now.
                  */
-                p->ptrace = 0;
-                remove_parent(p);
-                p->parent = p->real_parent;
-                add_parent(p);
+                if (!task_detached(p) && thread_group_empty(p)) {
+                        if (!same_thread_group(p->real_parent, parent))
+                                do_notify_parent(p, p->exit_signal);
+                        else {
+                                if (ign < 0)
+                                        ign = ignoring_children(parent);
+                                if (ign)
+                                        p->exit_signal = -1;
+                        }
+                }
 
-                if (task_is_traced(p)) {
+                if (task_detached(p)) {
                         /*
-                         * If it was at a trace stop, turn it into
-                         * a normal stop since it's no longer being
-                         * traced.
+                         * Mark it as in the process of being reaped.
                          */
-                        ptrace_untrace(p);
+                        p->exit_state = EXIT_DEAD;
+                        list_add(&p->ptrace_entry, dead);
                 }
         }
+}
+
+/*
+ * Finish up exit-time ptrace cleanup.
+ *
+ * Called without locks.
+ */
+static void ptrace_exit_finish(struct task_struct *parent,
+                               struct list_head *dead)
+{
+        struct task_struct *p, *n;
+
+        BUG_ON(!list_empty(&parent->ptraced));
+
+        list_for_each_entry_safe(p, n, dead, ptrace_entry) {
+                list_del_init(&p->ptrace_entry);
+                release_task(p);
+        }
+}
+
+static void reparent_thread(struct task_struct *p, struct task_struct *father)
+{
+        if (p->pdeath_signal)
+                /* We already hold the tasklist_lock here.  */
+                group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
+
+        list_move_tail(&p->sibling, &p->real_parent->children);
 
         /* If this is a threaded reparent there is no need to
          * notify anyone anything has happened.
@@ -737,7 +807,8 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
         /* If we'd notified the old parent about this child's death,
          * also notify the new parent.
          */
-        if (!traced && p->exit_state == EXIT_ZOMBIE &&
+        if (!ptrace_reparented(p) &&
+            p->exit_state == EXIT_ZOMBIE &&
             !task_detached(p) && thread_group_empty(p))
                 do_notify_parent(p, p->exit_signal);
 
@@ -754,12 +825,15 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
 static void forget_original_parent(struct task_struct *father)
 {
         struct task_struct *p, *n, *reaper = father;
-        struct list_head ptrace_dead;
-
-        INIT_LIST_HEAD(&ptrace_dead);
+        LIST_HEAD(ptrace_dead);
 
         write_lock_irq(&tasklist_lock);
 
+        /*
+         * First clean up ptrace if we were using it.
+         */
+        ptrace_exit(father, &ptrace_dead);
+
         do {
                 reaper = next_thread(reaper);
                 if (reaper == father) {
@@ -768,58 +842,19 @@ static void forget_original_parent(struct task_struct *father)
                 }
         } while (reaper->flags & PF_EXITING);
 
-        /*
-         * 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_entry_safe(p, n, &father->children, sibling) {
-                int ptrace;
-
-                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 */
-                        p->real_parent = reaper;
-                        reparent_thread(p, father, 0);
-                } else {
-                        /* reparent ptraced task to its real parent */
-                        __ptrace_unlink (p);
-                        if (p->exit_state == EXIT_ZOMBIE && !task_detached(p) &&
-                            thread_group_empty(p))
-                                do_notify_parent(p, p->exit_signal);
-                }
-
-                /*
-                 * if the ptraced child is a detached zombie 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 && task_detached(p)))
-                        list_add(&p->ptrace_list, &ptrace_dead);
-        }
-
-        list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) {
                 p->real_parent = reaper;
-                reparent_thread(p, father, 1);
+                if (p->parent == father) {
+                        BUG_ON(p->ptrace);
+                        p->parent = p->real_parent;
+                }
+                reparent_thread(p, father);
         }
 
         write_unlock_irq(&tasklist_lock);
         BUG_ON(!list_empty(&father->children));
-        BUG_ON(!list_empty(&father->ptrace_children));
-
-        list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) {
-                list_del_init(&p->ptrace_list);
-                release_task(p);
-        }
 
+        ptrace_exit_finish(father, &ptrace_dead);
 }
 
 /*
@@ -1180,13 +1215,6 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options,
                         return 0;
         }
 
-        /*
-         * Do not consider detached threads that are
-         * not ptraced:
-         */
-        if (task_detached(p) && !p->ptrace)
-                return 0;
-
         /* Wait for all children (clone and not) if __WALL is set;
          * otherwise, wait for clone children *only* if __WCLONE is
          * set; otherwise, wait for non-clone children *only*.  (Note:
@@ -1197,14 +1225,10 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options,
                 return 0;
 
         err = security_task_wait(p);
-        if (likely(!err))
-                return 1;
+        if (err)
+                return err;
 
-        if (type != PIDTYPE_PID)
-                return 0;
-        /* This child was explicitly requested, abort */
-        read_unlock(&tasklist_lock);
-        return err;
+        return 1;
 }
 
 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
@@ -1238,7 +1262,7 @@ static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
  * 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(struct task_struct *p, int noreap,
+static int wait_task_zombie(struct task_struct *p, int options,
                             struct siginfo __user *infop,
                             int __user *stat_addr, struct rusage __user *ru)
 {
@@ -1246,7 +1270,10 @@ static int wait_task_zombie(struct task_struct *p, int noreap,
         int retval, status, traced;
         pid_t pid = task_pid_vnr(p);
 
-        if (unlikely(noreap)) {
+        if (!likely(options & WEXITED))
+                return 0;
+
+        if (unlikely(options & WNOWAIT)) {
                 uid_t uid = p->uid;
                 int exit_code = p->exit_code;
                 int why, status;
@@ -1396,21 +1423,24 @@ static int wait_task_zombie(struct task_struct *p, int noreap,
  * 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(struct task_struct *p,
-                             int noreap, struct siginfo __user *infop,
+static int wait_task_stopped(int ptrace, struct task_struct *p,
+                             int options, struct siginfo __user *infop,
                              int __user *stat_addr, struct rusage __user *ru)
 {
         int retval, exit_code, why;
         uid_t uid = 0; /* unneeded, required by compiler */
         pid_t pid;
 
+        if (!(options & WUNTRACED))
+                return 0;
+
         exit_code = 0;
         spin_lock_irq(&p->sighand->siglock);
 
         if (unlikely(!task_is_stopped_or_traced(p)))
                 goto unlock_sig;
 
-        if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0)
+        if (!ptrace && p->signal->group_stop_count > 0)
                 /*
                  * A group stop is in progress and this is the group leader.
                  * We won't report until all threads have stopped.
@@ -1421,7 +1451,7 @@ static int wait_task_stopped(struct task_struct *p,
         if (!exit_code)
                 goto unlock_sig;
 
-        if (!noreap)
+        if (!unlikely(options & WNOWAIT))
                 p->exit_code = 0;
 
         uid = p->uid;
@@ -1439,10 +1469,10 @@ unlock_sig:
          */
         get_task_struct(p);
         pid = task_pid_vnr(p);
-        why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
+        why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
         read_unlock(&tasklist_lock);
 
-        if (unlikely(noreap))
+        if (unlikely(options & WNOWAIT))
                 return wait_noreap_copyout(p, pid, uid,
                                            why, exit_code,
                                            infop, ru);
@@ -1476,7 +1506,7 @@ unlock_sig:
  * 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(struct task_struct *p, int noreap,
+static int wait_task_continued(struct task_struct *p, int options,
                                struct siginfo __user *infop,
                                int __user *stat_addr, struct rusage __user *ru)
 {
@@ -1484,6 +1514,9 @@ static int wait_task_continued(struct task_struct *p, int noreap,
         pid_t pid;
         uid_t uid;
 
+        if (!unlikely(options & WCONTINUED))
+                return 0;
+
         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
                 return 0;
 
@@ -1493,7 +1526,7 @@ static int wait_task_continued(struct task_struct *p, int noreap,
                 spin_unlock_irq(&p->sighand->siglock);
                 return 0;
         }
-        if (!noreap)
+        if (!unlikely(options & WNOWAIT))
                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
         spin_unlock_irq(&p->sighand->siglock);
 
@@ -1519,89 +1552,161 @@ static int wait_task_continued(struct task_struct *p, int noreap,
         return retval;
 }
 
+/*
+ * Consider @p for a wait by @parent.
+ *
+ * -ECHILD should be in *@notask_error before the first call.
+ * Returns nonzero for a final return, when we have unlocked tasklist_lock.
+ * Returns zero if the search for a child should continue;
+ * then *@notask_error is 0 if @p is an eligible child,
+ * or another error from security_task_wait(), or still -ECHILD.
+ */
+static int wait_consider_task(struct task_struct *parent, int ptrace,
+                              struct task_struct *p, int *notask_error,
+                              enum pid_type type, struct pid *pid, int options,
+                              struct siginfo __user *infop,
+                              int __user *stat_addr, struct rusage __user *ru)
+{
+        int ret = eligible_child(type, pid, options, p);
+        if (!ret)
+                return ret;
+
+        if (unlikely(ret < 0)) {
+                /*
+                 * If we have not yet seen any eligible child,
+                 * then let this error code replace -ECHILD.
+                 * A permission error will give the user a clue
+                 * to look for security policy problems, rather
+                 * than for mysterious wait bugs.
+                 */
+                if (*notask_error)
+                        *notask_error = ret;
+        }
+
+        if (likely(!ptrace) && unlikely(p->ptrace)) {
+                /*
+                 * This child is hidden by ptrace.
+                 * We aren't allowed to see it now, but eventually we will.
+                 */
+                *notask_error = 0;
+                return 0;
+        }
+
+        if (p->exit_state == EXIT_DEAD)
+                return 0;
+
+        /*
+         * We don't reap group leaders with subthreads.
+         */
+        if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
+                return wait_task_zombie(p, options, infop, stat_addr, ru);
+
+        /*
+         * It's stopped or running now, so it might
+         * later continue, exit, or stop again.
+         */
+        *notask_error = 0;
+
+        if (task_is_stopped_or_traced(p))
+                return wait_task_stopped(ptrace, p, options,
+                                         infop, stat_addr, ru);
+
+        return wait_task_continued(p, options, infop, stat_addr, ru);
+}
+
+/*
+ * Do the work of do_wait() for one thread in the group, @tsk.
+ *
+ * -ECHILD should be in *@notask_error before the first call.
+ * Returns nonzero for a final return, when we have unlocked tasklist_lock.
+ * Returns zero if the search for a child should continue; then
+ * *@notask_error is 0 if there were any eligible children,
+ * or another error from security_task_wait(), or still -ECHILD.
+ */
+static int do_wait_thread(struct task_struct *tsk, int *notask_error,
+                          enum pid_type type, struct pid *pid, int options,
+                          struct siginfo __user *infop, int __user *stat_addr,
+                          struct rusage __user *ru)
+{
+        struct task_struct *p;
+
+        list_for_each_entry(p, &tsk->children, sibling) {
+                /*
+                 * Do not consider detached threads.
+                 */
+                if (!task_detached(p)) {
+                        int ret = wait_consider_task(tsk, 0, p, notask_error,
+                                                     type, pid, options,
+                                                     infop, stat_addr, ru);
+                        if (ret)
+                                return ret;
+                }
+        }
+
+        return 0;
+}
+
+static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
+                          enum pid_type type, struct pid *pid, int options,
+                          struct siginfo __user *infop, int __user *stat_addr,
+                          struct rusage __user *ru)
+{
+        struct task_struct *p;
+
+        /*
+         * Traditionally we see ptrace'd stopped tasks regardless of options.
+         */
+        options |= WUNTRACED;
+
+        list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
+                int ret = wait_consider_task(tsk, 1, p, notask_error,
+                                             type, pid, options,
+                                             infop, stat_addr, ru);
+                if (ret)
+                        return ret;
+        }
+
+        return 0;
+}
+
 static long do_wait(enum pid_type type, struct pid *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;
+        int retval;
 
         add_wait_queue(&current->signal->wait_chldexit,&wait);
 repeat:
-        /* If there is nothing that can match our critier just get out */
+        /*
+         * If there is nothing that can match our critiera just get out.
+         * We will clear @retval to zero if we see any child that might later
+         * match our criteria, even if we are not able to reap it yet.
+         */
         retval = -ECHILD;
         if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
                 goto end;
 
-        /*
-         * 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 = retval = 0;
         current->state = TASK_INTERRUPTIBLE;
         read_lock(&tasklist_lock);
         tsk = current;
         do {
-                struct task_struct *p;
-
-                list_for_each_entry(p, &tsk->children, sibling) {
-                        int ret = eligible_child(type, pid, options, p);
-                        if (!ret)
-                                continue;
-
-                        if (unlikely(ret < 0)) {
-                                retval = ret;
-                        } else if (task_is_stopped_or_traced(p)) {
-                                /*
-                                 * It's stopped now, so it might later
-                                 * continue, exit, or stop again.
-                                 */
-                                flag = 1;
-                                if (!(p->ptrace & PT_PTRACED) &&
-                                    !(options & WUNTRACED))
-                                        continue;
-
-                                retval = wait_task_stopped(p,
-                                                (options & WNOWAIT), infop,
-                                                stat_addr, ru);
-                        } else if (p->exit_state == EXIT_ZOMBIE &&
-                                        !delay_group_leader(p)) {
-                                /*
-                                 * We don't reap group leaders with subthreads.
-                                 */
-                                if (!likely(options & WEXITED))
-                                        continue;
-                                retval = wait_task_zombie(p,
-                                                (options & WNOWAIT), infop,
-                                                stat_addr, ru);
-                        } else if (p->exit_state != EXIT_DEAD) {
-                                /*
-                                 * It's running now, so it might later
-                                 * exit, stop, or stop and then continue.
-                                 */
-                                flag = 1;
-                                if (!unlikely(options & WCONTINUED))
-                                        continue;
-                                retval = wait_task_continued(p,
-                                                (options & WNOWAIT), infop,
-                                                stat_addr, ru);
-                        }
-                        if (retval != 0) /* tasklist_lock released */
-                                goto end;
-                }
-                if (!flag) {
-                        list_for_each_entry(p, &tsk->ptrace_children,
-                                                                ptrace_list) {
-                                flag = eligible_child(type, pid, options, p);
-                                if (!flag)
-                                        continue;
-                                if (likely(flag > 0))
-                                        break;
-                                retval = flag;
-                                goto end;
-                        }
+                int tsk_result = do_wait_thread(tsk, &retval,
+                                                type, pid, options,
+                                                infop, stat_addr, ru);
+                if (!tsk_result)
+                        tsk_result = ptrace_do_wait(tsk, &retval,
+                                                    type, pid, options,
+                                                    infop, stat_addr, ru);
+                if (tsk_result) {
+                        /*
+                         * tasklist_lock is unlocked and we have a final result.
+                         */
+                        retval = tsk_result;
+                        goto end;
                 }
+
                 if (options & __WNOTHREAD)
                         break;
                 tsk = next_thread(tsk);
@@ -1609,16 +1714,14 @@ repeat:
         } while (tsk != current);
         read_unlock(&tasklist_lock);
 
-        if (flag) {
-                if (options & WNOHANG)
-                        goto end;
+        if (!retval && !(options & WNOHANG)) {
                 retval = -ERESTARTSYS;
-                if (signal_pending(current))
-                        goto end;
-                schedule();
-                goto repeat;
+                if (!signal_pending(current)) {
+                        schedule();
+                        goto repeat;
+                }
         }
-        retval = -ECHILD;
+
 end:
         current->state = TASK_RUNNING;
         remove_wait_queue(&current->signal->wait_chldexit,&wait);
diff --git a/kernel/fork.c b/kernel/fork.c
index 4bd2f516401f..adefc1131f27 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1125,8 +1125,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
          */
         p->group_leader = p;
         INIT_LIST_HEAD(&p->thread_group);
-        INIT_LIST_HEAD(&p->ptrace_children);
-        INIT_LIST_HEAD(&p->ptrace_list);
+        INIT_LIST_HEAD(&p->ptrace_entry);
+        INIT_LIST_HEAD(&p->ptraced);
 
         /* Now that the task is set up, run cgroup callbacks if
          * necessary. We need to run them before the task is visible
@@ -1198,7 +1198,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         }
 
         if (likely(p->pid)) {
-                add_parent(p);
+                list_add_tail(&p->sibling, &p->real_parent->children);
                 if (unlikely(p->ptrace & PT_PTRACED))
                         __ptrace_link(p, current->parent);
 
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 97747cdd37c9..ac3fb7326641 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -235,7 +235,7 @@ int kthreadd(void *unused)
         set_user_nice(tsk, KTHREAD_NICE_LEVEL);
         set_cpus_allowed(tsk, CPU_MASK_ALL);
 
-        current->flags |= PF_NOFREEZE;
+        current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;
 
         for (;;) {
                 set_current_state(TASK_INTERRUPTIBLE);
diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 14a656cdc652..f011e0870b52 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -180,6 +180,17 @@ static void platform_restore_cleanup(int platform_mode)
 }
 
 /**
+ *      platform_recover - recover the platform from a failure to suspend
+ *      devices.
+ */
+
+static void platform_recover(int platform_mode)
+{
+        if (platform_mode && hibernation_ops && hibernation_ops->recover)
+                hibernation_ops->recover();
+}
+
+/**
  *      create_image - freeze devices that need to be frozen with interrupts
  *      off, create the hibernation image and thaw those devices.  Control
  *      reappears in this routine after a restore.
@@ -193,6 +204,7 @@ static int create_image(int platform_mode)
         if (error)
                 return error;
 
+        device_pm_lock();
         local_irq_disable();
         /* At this point, device_suspend() has been called, but *not*
          * device_power_down(). We *must* call device_power_down() now.
@@ -224,9 +236,11 @@ static int create_image(int platform_mode)
         /* NOTE:  device_power_up() is just a resume() for devices
          * that suspended with irqs off ... no overall powerup.
          */
-        device_power_up();
+        device_power_up(in_suspend ?
+                (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
  Enable_irqs:
         local_irq_enable();
+        device_pm_unlock();
         return error;
 }
 
@@ -255,10 +269,10 @@ int hibernation_snapshot(int platform_mode)
         suspend_console();
         error = device_suspend(PMSG_FREEZE);
         if (error)
-                goto Resume_console;
+                goto Recover_platform;
 
         if (hibernation_test(TEST_DEVICES))
-                goto Resume_devices;
+                goto Recover_platform;
 
         error = platform_pre_snapshot(platform_mode);
         if (error || hibernation_test(TEST_PLATFORM))
@@ -280,12 +294,16 @@ int hibernation_snapshot(int platform_mode)
  Finish:
         platform_finish(platform_mode);
  Resume_devices:
-        device_resume();
- Resume_console:
+        device_resume(in_suspend ?
+                (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
         resume_console();
  Close:
         platform_end(platform_mode);
         return error;
+
+ Recover_platform:
+        platform_recover(platform_mode);
+        goto Resume_devices;
 }
 
 /**
@@ -300,8 +318,9 @@ static int resume_target_kernel(void)
 {
         int error;
 
+        device_pm_lock();
         local_irq_disable();
-        error = device_power_down(PMSG_PRETHAW);
+        error = device_power_down(PMSG_QUIESCE);
         if (error) {
                 printk(KERN_ERR "PM: Some devices failed to power down, "
                         "aborting resume\n");
@@ -329,9 +348,10 @@ static int resume_target_kernel(void)
         swsusp_free();
         restore_processor_state();
         touch_softlockup_watchdog();
-        device_power_up();
+        device_power_up(PMSG_RECOVER);
  Enable_irqs:
         local_irq_enable();
+        device_pm_unlock();
         return error;
 }
 
@@ -350,7 +370,7 @@ int hibernation_restore(int platform_mode)
 
         pm_prepare_console();
         suspend_console();
-        error = device_suspend(PMSG_PRETHAW);
+        error = device_suspend(PMSG_QUIESCE);
         if (error)
                 goto Finish;
 
@@ -362,7 +382,7 @@ int hibernation_restore(int platform_mode)
                 enable_nonboot_cpus();
         }
         platform_restore_cleanup(platform_mode);
-        device_resume();
+        device_resume(PMSG_RECOVER);
  Finish:
         resume_console();
         pm_restore_console();
@@ -392,8 +412,11 @@ int hibernation_platform_enter(void)
 
         suspend_console();
         error = device_suspend(PMSG_HIBERNATE);
-        if (error)
-                goto Resume_console;
+        if (error) {
+                if (hibernation_ops->recover)
+                        hibernation_ops->recover();
+                goto Resume_devices;
+        }
 
         error = hibernation_ops->prepare();
         if (error)
@@ -403,6 +426,7 @@ int hibernation_platform_enter(void)
         if (error)
                 goto Finish;
 
+        device_pm_lock();
         local_irq_disable();
         error = device_power_down(PMSG_HIBERNATE);
         if (!error) {
@@ -411,6 +435,7 @@ int hibernation_platform_enter(void)
                 while (1);
         }
         local_irq_enable();
+        device_pm_unlock();
 
         /*
          * We don't need to reenable the nonboot CPUs or resume consoles, since
@@ -419,8 +444,7 @@ int hibernation_platform_enter(void)
  Finish:
         hibernation_ops->finish();
  Resume_devices:
-        device_resume();
- Resume_console:
+        device_resume(PMSG_RESTORE);
         resume_console();
  Close:
         hibernation_ops->end();
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 6a6d5eb3524e..3398f4651aa1 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -228,6 +228,7 @@ static int suspend_enter(suspend_state_t state)
 {
         int error = 0;
 
+        device_pm_lock();
         arch_suspend_disable_irqs();
         BUG_ON(!irqs_disabled());
 
@@ -239,10 +240,11 @@ static int suspend_enter(suspend_state_t state)
         if (!suspend_test(TEST_CORE))
                 error = suspend_ops->enter(state);
 
-        device_power_up();
+        device_power_up(PMSG_RESUME);
  Done:
         arch_suspend_enable_irqs();
         BUG_ON(irqs_disabled());
+        device_pm_unlock();
         return error;
 }
 
@@ -267,11 +269,11 @@ int suspend_devices_and_enter(suspend_state_t state)
         error = device_suspend(PMSG_SUSPEND);
         if (error) {
                 printk(KERN_ERR "PM: Some devices failed to suspend\n");
-                goto Resume_console;
+                goto Recover_platform;
         }
 
         if (suspend_test(TEST_DEVICES))
-                goto Resume_devices;
+                goto Recover_platform;
 
         if (suspend_ops->prepare) {
                 error = suspend_ops->prepare();
@@ -291,13 +293,17 @@ int suspend_devices_and_enter(suspend_state_t state)
         if (suspend_ops->finish)
                 suspend_ops->finish();
  Resume_devices:
-        device_resume();
- Resume_console:
+        device_resume(PMSG_RESUME);
         resume_console();
  Close:
         if (suspend_ops->end)
                 suspend_ops->end();
         return error;
+
+ Recover_platform:
+        if (suspend_ops->recover)
+                suspend_ops->recover();
+        goto Resume_devices;
 }
 
 /**
diff --git a/kernel/power/process.c b/kernel/power/process.c
index f1d0b345c9ba..5fb87652f214 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -19,9 +19,6 @@
  */
 #define TIMEOUT (20 * HZ)
 
-#define FREEZER_KERNEL_THREADS 0
-#define FREEZER_USER_SPACE 1
-
 static inline int freezeable(struct task_struct * p)
 {
         if ((p == current) ||
@@ -84,63 +81,53 @@ static void fake_signal_wake_up(struct task_struct *p)
         spin_unlock_irqrestore(&p->sighand->siglock, flags);
 }
 
-static int has_mm(struct task_struct *p)
+static inline bool should_send_signal(struct task_struct *p)
 {
-        return (p->mm && !(p->flags & PF_BORROWED_MM));
+        return !(p->flags & PF_FREEZER_NOSIG);
 }
 
 /**
  *      freeze_task - send a freeze request to given task
  *      @p: task to send the request to
- *      @with_mm_only: if set, the request will only be sent if the task has its
- *              own mm
- *      Return value: 0, if @with_mm_only is set and the task has no mm of its
- *              own or the task is frozen, 1, otherwise
+ *      @sig_only: if set, the request will only be sent if the task has the
+ *              PF_FREEZER_NOSIG flag unset
+ *      Return value: 'false', if @sig_only is set and the task has
+ *              PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
  *
- *      The freeze request is sent by seting the tasks's TIF_FREEZE flag and
+ *      The freeze request is sent by setting the tasks's TIF_FREEZE flag and
  *      either sending a fake signal to it or waking it up, depending on whether
- *      or not it has its own mm (ie. it is a user land task).  If @with_mm_only
- *      is set and the task has no mm of its own (ie. it is a kernel thread),
- *      its TIF_FREEZE flag should not be set.
- *
- *      The task_lock() is necessary to prevent races with exit_mm() or
- *      use_mm()/unuse_mm() from occuring.
+ *      or not it has PF_FREEZER_NOSIG set.  If @sig_only is set and the task
+ *      has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
+ *      TIF_FREEZE flag will not be set.
  */
-static int freeze_task(struct task_struct *p, int with_mm_only)
+static bool freeze_task(struct task_struct *p, bool sig_only)
 {
-        int ret = 1;
+        /*
+         * We first check if the task is freezing and next if it has already
+         * been frozen to avoid the race with frozen_process() which first marks
+         * the task as frozen and next clears its TIF_FREEZE.
+         */
+        if (!freezing(p)) {
+                rmb();
+                if (frozen(p))
+                        return false;
 
-        task_lock(p);
-        if (freezing(p)) {
-                if (has_mm(p)) {
-                        if (!signal_pending(p))
-                                fake_signal_wake_up(p);
-                } else {
-                        if (with_mm_only)
-                                ret = 0;
-                        else
-                                wake_up_state(p, TASK_INTERRUPTIBLE);
-                }
+                if (!sig_only || should_send_signal(p))
+                        set_freeze_flag(p);
+                else
+                        return false;
+        }
+
+        if (should_send_signal(p)) {
+                if (!signal_pending(p))
+                        fake_signal_wake_up(p);
+        } else if (sig_only) {
+                return false;
         } else {
-                rmb();
-                if (frozen(p)) {
-                        ret = 0;
-                } else {
-                        if (has_mm(p)) {
-                                set_freeze_flag(p);
-                                fake_signal_wake_up(p);
-                        } else {
-                                if (with_mm_only) {
-                                        ret = 0;
-                                } else {
-                                        set_freeze_flag(p);
-                                        wake_up_state(p, TASK_INTERRUPTIBLE);
-                                }
-                        }
-                }
+                wake_up_state(p, TASK_INTERRUPTIBLE);
         }
-        task_unlock(p);
-        return ret;
+
+        return true;
 }
 
 static void cancel_freezing(struct task_struct *p)
@@ -156,7 +143,7 @@ static void cancel_freezing(struct task_struct *p)
         }
 }
 
-static int try_to_freeze_tasks(int freeze_user_space)
+static int try_to_freeze_tasks(bool sig_only)
 {
         struct task_struct *g, *p;
         unsigned long end_time;
@@ -175,7 +162,7 @@ static int try_to_freeze_tasks(int freeze_user_space)
                         if (frozen(p) || !freezeable(p))
                                 continue;
 
-                        if (!freeze_task(p, freeze_user_space))
+                        if (!freeze_task(p, sig_only))
                                 continue;
 
                         /*
@@ -235,13 +222,13 @@ int freeze_processes(void)
         int error;
 
         printk("Freezing user space processes ... ");
-        error = try_to_freeze_tasks(FREEZER_USER_SPACE);
+        error = try_to_freeze_tasks(true);
         if (error)
                 goto Exit;
         printk("done.\n");
 
         printk("Freezing remaining freezable tasks ... ");
-        error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
+        error = try_to_freeze_tasks(false);
         if (error)
                 goto Exit;
         printk("done.");
@@ -251,7 +238,7 @@ int freeze_processes(void)
         return error;
 }
 
-static void thaw_tasks(int thaw_user_space)
+static void thaw_tasks(bool nosig_only)
 {
         struct task_struct *g, *p;
 
@@ -260,7 +247,7 @@ static void thaw_tasks(int thaw_user_space)
                 if (!freezeable(p))
                         continue;
 
-                if (!p->mm == thaw_user_space)
+                if (nosig_only && should_send_signal(p))
                         continue;
 
                 thaw_process(p);
@@ -271,8 +258,8 @@ static void thaw_tasks(int thaw_user_space)
 void thaw_processes(void)
 {
         printk("Restarting tasks ... ");
-        thaw_tasks(FREEZER_KERNEL_THREADS);
-        thaw_tasks(FREEZER_USER_SPACE);
+        thaw_tasks(true);
+        thaw_tasks(false);
         schedule();
         printk("done.\n");
 }
diff --git a/kernel/power/user.c b/kernel/power/user.c
index f5512cb3aa86..a6332a313262 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -23,6 +23,7 @@
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
+#include <linux/smp_lock.h>
 
 #include <asm/uaccess.h>
 
@@ -69,16 +70,22 @@ static int snapshot_open(struct inode *inode, struct file *filp)
         struct snapshot_data *data;
         int error;
 
-        if (!atomic_add_unless(&snapshot_device_available, -1, 0))
-                return -EBUSY;
+        mutex_lock(&pm_mutex);
+
+        if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
+                error = -EBUSY;
+                goto Unlock;
+        }
 
         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
                 atomic_inc(&snapshot_device_available);
-                return -ENOSYS;
+                error = -ENOSYS;
+                goto Unlock;
         }
         if(create_basic_memory_bitmaps()) {
                 atomic_inc(&snapshot_device_available);
-                return -ENOMEM;
+                error = -ENOMEM;
+                goto Unlock;
         }
         nonseekable_open(inode, filp);
         data = &snapshot_state;
@@ -98,33 +105,36 @@ static int snapshot_open(struct inode *inode, struct file *filp)
                 if (error)
                         pm_notifier_call_chain(PM_POST_HIBERNATION);
         }
-        if (error) {
+        if (error)
                 atomic_inc(&snapshot_device_available);
-                return error;
-        }
         data->frozen = 0;
         data->ready = 0;
         data->platform_support = 0;
 
-        return 0;
+ Unlock:
+        mutex_unlock(&pm_mutex);
+
+        return error;
 }
 
 static int snapshot_release(struct inode *inode, struct file *filp)
 {
         struct snapshot_data *data;
 
+        mutex_lock(&pm_mutex);
+
         swsusp_free();
         free_basic_memory_bitmaps();
         data = filp->private_data;
         free_all_swap_pages(data->swap);
-        if (data->frozen) {
-                mutex_lock(&pm_mutex);
+        if (data->frozen)
                 thaw_processes();
-                mutex_unlock(&pm_mutex);
-        }
         pm_notifier_call_chain(data->mode == O_WRONLY ?
                         PM_POST_HIBERNATION : PM_POST_RESTORE);
         atomic_inc(&snapshot_device_available);
+
+        mutex_unlock(&pm_mutex);
+
         return 0;
 }
 
@@ -134,9 +144,13 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
         struct snapshot_data *data;
         ssize_t res;
 
+        mutex_lock(&pm_mutex);
+
         data = filp->private_data;
-        if (!data->ready)
-                return -ENODATA;
+        if (!data->ready) {
+                res = -ENODATA;
+                goto Unlock;
+        }
         res = snapshot_read_next(&data->handle, count);
         if (res > 0) {
                 if (copy_to_user(buf, data_of(data->handle), res))
@@ -144,6 +158,10 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
                 else
                         *offp = data->handle.offset;
         }
+
+ Unlock:
+        mutex_unlock(&pm_mutex);
+
         return res;
 }
 
@@ -153,6 +171,8 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,
         struct snapshot_data *data;
         ssize_t res;
 
+        mutex_lock(&pm_mutex);
+
         data = filp->private_data;
         res = snapshot_write_next(&data->handle, count);
         if (res > 0) {
@@ -161,11 +181,14 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,
                 else
                         *offp = data->handle.offset;
         }
+
+        mutex_unlock(&pm_mutex);
+
         return res;
 }
 
-static int snapshot_ioctl(struct inode *inode, struct file *filp,
-                          unsigned int cmd, unsigned long arg)
+static long snapshot_ioctl(struct file *filp, unsigned int cmd,
+                                                        unsigned long arg)
 {
         int error = 0;
         struct snapshot_data *data;
@@ -179,6 +202,9 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
+        if (!mutex_trylock(&pm_mutex))
+                return -EBUSY;
+
         data = filp->private_data;
 
         switch (cmd) {
@@ -186,7 +212,6 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
         case SNAPSHOT_FREEZE:
                 if (data->frozen)
                         break;
-                mutex_lock(&pm_mutex);
                 printk("Syncing filesystems ... ");
                 sys_sync();
                 printk("done.\n");
@@ -194,7 +219,6 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                 error = freeze_processes();
                 if (error)
                         thaw_processes();
-                mutex_unlock(&pm_mutex);
                 if (!error)
                         data->frozen = 1;
                 break;
@@ -202,9 +226,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
         case SNAPSHOT_UNFREEZE:
                 if (!data->frozen || data->ready)
                         break;
-                mutex_lock(&pm_mutex);
                 thaw_processes();
-                mutex_unlock(&pm_mutex);
                 data->frozen = 0;
                 break;
 
@@ -307,16 +329,11 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                         error = -EPERM;
                         break;
                 }
-                if (!mutex_trylock(&pm_mutex)) {
-                        error = -EBUSY;
-                        break;
-                }
                 /*
                  * Tasks are frozen and the notifiers have been called with
                  * PM_HIBERNATION_PREPARE
                  */
                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
-                mutex_unlock(&pm_mutex);
                 break;
 
         case SNAPSHOT_PLATFORM_SUPPORT:
@@ -390,6 +407,8 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
 
         }
 
+        mutex_unlock(&pm_mutex);
+
         return error;
 }
 
@@ -399,7 +418,7 @@ static const struct file_operations snapshot_fops = {
         .read = snapshot_read,
         .write = snapshot_write,
         .llseek = no_llseek,
-        .ioctl = snapshot_ioctl,
+        .unlocked_ioctl = snapshot_ioctl,
 };
 
 static struct miscdevice snapshot_device = {
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index e337390fce01..8392a9da6450 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -33,13 +33,9 @@
  */
 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 {
-        BUG_ON(!list_empty(&child->ptrace_list));
-        if (child->parent == new_parent)
-                return;
-        list_add(&child->ptrace_list, &child->parent->ptrace_children);
-        remove_parent(child);
+        BUG_ON(!list_empty(&child->ptrace_entry));
+        list_add(&child->ptrace_entry, &new_parent->ptraced);
         child->parent = new_parent;
-        add_parent(child);
 }
  
 /*
@@ -73,12 +69,8 @@ void __ptrace_unlink(struct task_struct *child)
         BUG_ON(!child->ptrace);
 
         child->ptrace = 0;
-        if (ptrace_reparented(child)) {
-                list_del_init(&child->ptrace_list);
-                remove_parent(child);
-                child->parent = child->real_parent;
-                add_parent(child);
-        }
+        child->parent = child->real_parent;
+        list_del_init(&child->ptrace_entry);
 
         if (task_is_traced(child))
                 ptrace_untrace(child);
@@ -492,15 +484,34 @@ int ptrace_traceme(void)
         /*
          * Are we already being traced?
          */
+repeat:
         task_lock(current);
         if (!(current->ptrace & PT_PTRACED)) {
+                /*
+                 * See ptrace_attach() comments about the locking here.
+                 */
+                unsigned long flags;
+                if (!write_trylock_irqsave(&tasklist_lock, flags)) {
+                        task_unlock(current);
+                        do {
+                                cpu_relax();
+                        } while (!write_can_lock(&tasklist_lock));
+                        goto repeat;
+                }
+
                 ret = security_ptrace(current->parent, current,
                                       PTRACE_MODE_ATTACH);
+
                 /*
                  * Set the ptrace bit in the process ptrace flags.
+                 * Then link us on our parent's ptraced list.
                  */
-                if (!ret)
+                if (!ret) {
                         current->ptrace |= PT_PTRACED;
+                        __ptrace_link(current, current->real_parent);
+                }
+
+                write_unlock_irqrestore(&tasklist_lock, flags);
         }
         task_unlock(current);
         return ret;