diff options
Diffstat (limited to 'fs/exec.c')
| -rw-r--r-- | fs/exec.c | 70 |
1 files changed, 38 insertions, 32 deletions
diff --git a/fs/exec.c b/fs/exec.c index c7397c46ad6d..3a79d97ac234 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -561,7 +561,7 @@ static int exec_mmap(struct mm_struct *mm) arch_pick_mmap_layout(mm); if (old_mm) { up_read(&old_mm->mmap_sem); - if (active_mm != old_mm) BUG(); + BUG_ON(active_mm != old_mm); mmput(old_mm); return 0; } @@ -616,6 +616,15 @@ static int de_thread(struct task_struct *tsk) kmem_cache_free(sighand_cachep, newsighand); return -EAGAIN; } + + /* + * child_reaper ignores SIGKILL, change it now. + * Reparenting needs write_lock on tasklist_lock, + * so it is safe to do it under read_lock. + */ + if (unlikely(current->group_leader == child_reaper)) + child_reaper = current; + zap_other_threads(current); read_unlock(&tasklist_lock); @@ -656,9 +665,7 @@ static int de_thread(struct task_struct *tsk) * and to assume its PID: */ if (!thread_group_leader(current)) { - struct task_struct *parent; struct dentry *proc_dentry1, *proc_dentry2; - unsigned long ptrace; /* * Wait for the thread group leader to be a zombie. @@ -669,6 +676,18 @@ static int de_thread(struct task_struct *tsk) while (leader->exit_state != EXIT_ZOMBIE) yield(); + /* + * The only record we have of the real-time age of a + * process, regardless of execs it's done, is start_time. + * All the past CPU time is accumulated in signal_struct + * from sister threads now dead. But in this non-leader + * exec, nothing survives from the original leader thread, + * whose birth marks the true age of this process now. + * When we take on its identity by switching to its PID, we + * also take its birthdate (always earlier than our own). + */ + current->start_time = leader->start_time; + spin_lock(&leader->proc_lock); spin_lock(¤t->proc_lock); proc_dentry1 = proc_pid_unhash(current); @@ -683,38 +702,26 @@ static int de_thread(struct task_struct *tsk) * two threads with a switched PID, and release * the former thread group leader: */ - ptrace = leader->ptrace; - parent = leader->parent; - if (unlikely(ptrace) && unlikely(parent == current)) { - /* - * Joker was ptracing his own group leader, - * and now he wants to be his own parent! - * We can't have that. - */ - ptrace = 0; - } - - ptrace_unlink(current); - ptrace_unlink(leader); - remove_parent(current); - remove_parent(leader); - switch_exec_pids(leader, current); + /* Become a process group leader with the old leader's pid. + * Note: The old leader also uses thispid until release_task + * is called. Odd but simple and correct. + */ + detach_pid(current, PIDTYPE_PID); + current->pid = leader->pid; + attach_pid(current, PIDTYPE_PID, current->pid); + attach_pid(current, PIDTYPE_PGID, current->signal->pgrp); + attach_pid(current, PIDTYPE_SID, current->signal->session); + list_add_tail_rcu(¤t->tasks, &init_task.tasks); - current->parent = current->real_parent = leader->real_parent; - leader->parent = leader->real_parent = child_reaper; current->group_leader = current; - leader->group_leader = leader; + leader->group_leader = current; - add_parent(current, current->parent); - add_parent(leader, leader->parent); - if (ptrace) { - current->ptrace = ptrace; - __ptrace_link(current, parent); - } + /* Reduce leader to a thread */ + detach_pid(leader, PIDTYPE_PGID); + detach_pid(leader, PIDTYPE_SID); + list_del_init(&leader->tasks); - list_del(¤t->tasks); - list_add_tail(¤t->tasks, &init_task.tasks); current->exit_signal = SIGCHLD; BUG_ON(leader->exit_state != EXIT_ZOMBIE); @@ -751,7 +758,6 @@ no_thread_group: /* * Move our state over to newsighand and switch it in. */ - spin_lock_init(&newsighand->siglock); atomic_set(&newsighand->count, 1); memcpy(newsighand->action, oldsighand->action, sizeof(newsighand->action)); @@ -768,7 +774,7 @@ no_thread_group: write_unlock_irq(&tasklist_lock); if (atomic_dec_and_test(&oldsighand->count)) - sighand_free(oldsighand); + kmem_cache_free(sighand_cachep, oldsighand); } BUG_ON(!thread_group_leader(current)); |
