diff options
| -rw-r--r-- | include/linux/sched/signal.h | 8 | ||||
| -rw-r--r-- | init/init_task.c | 1 | ||||
| -rw-r--r-- | kernel/fork.c | 43 | ||||
| -rw-r--r-- | kernel/signal.c | 15 |
4 files changed, 49 insertions, 18 deletions
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index ae2b0b81be25..4e9b77fb702d 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -69,6 +69,11 @@ struct thread_group_cputimer { bool checking_timer; }; +struct multiprocess_signals { + sigset_t signal; + struct hlist_node node; +}; + /* * NOTE! "signal_struct" does not have its own * locking, because a shared signal_struct always @@ -90,6 +95,9 @@ struct signal_struct { /* shared signal handling: */ struct sigpending shared_pending; + /* For collecting multiprocess signals during fork */ + struct hlist_head multiprocess; + /* thread group exit support */ int group_exit_code; /* overloaded: diff --git a/init/init_task.c b/init/init_task.c index 4f97846256d7..5aebe3be4d7c 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -22,6 +22,7 @@ static struct signal_struct init_signals = { .list = LIST_HEAD_INIT(init_signals.shared_pending.list), .signal = {{0}} }, + .multiprocess = HLIST_HEAD_INIT, .rlim = INIT_RLIMITS, .cred_guard_mutex = __MUTEX_INITIALIZER(init_signals.cred_guard_mutex), #ifdef CONFIG_POSIX_TIMERS diff --git a/kernel/fork.c b/kernel/fork.c index ab731e15a600..411e34acace7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1456,6 +1456,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) init_waitqueue_head(&sig->wait_chldexit); sig->curr_target = tsk; init_sigpending(&sig->shared_pending); + INIT_HLIST_HEAD(&sig->multiprocess); seqlock_init(&sig->stats_lock); prev_cputime_init(&sig->prev_cputime); @@ -1602,6 +1603,7 @@ static __latent_entropy struct task_struct *copy_process( { int retval; struct task_struct *p; + struct multiprocess_signals delayed; /* * Don't allow sharing the root directory with processes in a different @@ -1649,6 +1651,24 @@ static __latent_entropy struct task_struct *copy_process( return ERR_PTR(-EINVAL); } + /* + * Force any signals received before this point to be delivered + * before the fork happens. Collect up signals sent to multiple + * processes that happen during the fork and delay them so that + * they appear to happen after the fork. + */ + sigemptyset(&delayed.signal); + INIT_HLIST_NODE(&delayed.node); + + spin_lock_irq(¤t->sighand->siglock); + if (!(clone_flags & CLONE_THREAD)) + hlist_add_head(&delayed.node, ¤t->signal->multiprocess); + recalc_sigpending(); + spin_unlock_irq(¤t->sighand->siglock); + retval = -ERESTARTNOINTR; + if (signal_pending(current)) + goto fork_out; + retval = -ENOMEM; p = dup_task_struct(current, node); if (!p) @@ -1934,22 +1954,6 @@ static __latent_entropy struct task_struct *copy_process( goto bad_fork_cancel_cgroup; } - if (!(clone_flags & CLONE_THREAD)) { - /* - * Process group and session signals need to be delivered to just the - * parent before the fork or both the parent and the child after the - * fork. Restart if a signal comes in before we add the new process to - * it's process group. - * A fatal signal pending means that current will exit, so the new - * thread can't slip out of an OOM kill (or normal SIGKILL). - */ - recalc_sigpending(); - if (signal_pending(current)) { - retval = -ERESTARTNOINTR; - goto bad_fork_cancel_cgroup; - } - } - init_task_pid_links(p); if (likely(p->pid)) { @@ -1965,7 +1969,7 @@ static __latent_entropy struct task_struct *copy_process( ns_of_pid(pid)->child_reaper = p; p->signal->flags |= SIGNAL_UNKILLABLE; } - + p->signal->shared_pending.signal = delayed.signal; p->signal->tty = tty_kref_get(current->signal->tty); /* * Inherit has_child_subreaper flag under the same @@ -1993,8 +1997,8 @@ static __latent_entropy struct task_struct *copy_process( attach_pid(p, PIDTYPE_PID); nr_threads++; } - total_forks++; + hlist_del_init(&delayed.node); spin_unlock(¤t->sighand->siglock); syscall_tracepoint_update(p); write_unlock_irq(&tasklist_lock); @@ -2059,6 +2063,9 @@ bad_fork_free: put_task_stack(p); free_task(p); fork_out: + spin_lock_irq(¤t->sighand->siglock); + hlist_del_init(&delayed.node); + spin_unlock_irq(¤t->sighand->siglock); return ERR_PTR(retval); } diff --git a/kernel/signal.c b/kernel/signal.c index 9f0eafb6d474..cfa9d10e731a 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1121,6 +1121,21 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, out_set: signalfd_notify(t, sig); sigaddset(&pending->signal, sig); + + /* Let multiprocess signals appear after on-going forks */ + if (type > PIDTYPE_TGID) { + struct multiprocess_signals *delayed; + hlist_for_each_entry(delayed, &t->signal->multiprocess, node) { + sigset_t *signal = &delayed->signal; + /* Can't queue both a stop and a continue signal */ + if (sig == SIGCONT) + sigdelsetmask(signal, SIG_KERNEL_STOP_MASK); + else if (sig_kernel_stop(sig)) + sigdelset(signal, SIGCONT); + sigaddset(signal, sig); + } + } + complete_signal(sig, t, type); ret: trace_signal_generate(sig, info, t, type != PIDTYPE_PID, result); |