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static int copy_signal(unsigned long clone_flags, struct task_struct *tsk){ struct signal_struct *sig;  if (clone_flags & CLONE_THREAD)  return 0;  sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); tsk->signal = sig; if (!sig)  return -ENOMEM;  sig->nr_threads = 1; atomic_set(&sig->live, 1); atomic_set(&sig->sigcnt, 1);  /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);  init_waitqueue_head(&sig->wait_chldexit); sig->curr_target = tsk; init_sigpending(&sig->shared_pending); INIT_LIST_HEAD(&sig->posix_timers); seqlock_init(&sig->stats_lock); prev_cputime_init(&sig->prev_cputime);  hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); sig->real_timer.function = it_real_fn;  task_lock(current->group_leader); memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); task_unlock(current->group_leader);  posix_cpu_timers_init_group(sig);  tty_audit_fork(sig); sched_autogroup_fork(sig);  sig->oom_score_adj = current->signal->oom_score_adj; sig->oom_score_adj_min = current->signal->oom_score_adj_min;  sig->has_child_subreaper = current->signal->has_child_subreaper ||       current->signal->is_child_subreaper;  mutex_init(&sig->cred_guard_mutex);  return 0;}

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