diff options
| -rw-r--r-- | kernel/signal.c | 53 |
1 files changed, 50 insertions, 3 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 9f10b24..f65403d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1694,6 +1694,15 @@ static int sigkill_pending(struct task_struct *tsk) } /* + * Test whether the target task of the usual cldstop notification - the + * real_parent of @child - is in the same group as the ptracer. + */ +static bool real_parent_is_ptracer(struct task_struct *child) +{ + return same_thread_group(child->parent, child->real_parent); +} + +/* * This must be called with current->sighand->siglock held. * * This should be the path for all ptrace stops. @@ -1708,6 +1717,8 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) __releases(¤t->sighand->siglock) __acquires(¤t->sighand->siglock) { + bool gstop_done = false; + if (arch_ptrace_stop_needed(exit_code, info)) { /* * The arch code has something special to do before a @@ -1735,7 +1746,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) * is entered - ignore it. */ if (why == CLD_STOPPED && (current->group_stop & GROUP_STOP_PENDING)) - task_participate_group_stop(current); + gstop_done = task_participate_group_stop(current); current->last_siginfo = info; current->exit_code = exit_code; @@ -1757,7 +1768,20 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) spin_unlock_irq(¤t->sighand->siglock); read_lock(&tasklist_lock); if (may_ptrace_stop()) { - do_notify_parent_cldstop(current, task_ptrace(current), why); + /* + * Notify parents of the stop. + * + * While ptraced, there are two parents - the ptracer and + * the real_parent of the group_leader. The ptracer should + * know about every stop while the real parent is only + * interested in the completion of group stop. The states + * for the two don't interact with each other. Notify + * separately unless they're gonna be duplicates. + */ + do_notify_parent_cldstop(current, true, why); + if (gstop_done && !real_parent_is_ptracer(current)) + do_notify_parent_cldstop(current, false, why); + /* * Don't want to allow preemption here, because * sys_ptrace() needs this task to be inactive. @@ -1772,7 +1796,16 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info) /* * By the time we got the lock, our tracer went away. * Don't drop the lock yet, another tracer may come. + * + * If @gstop_done, the ptracer went away between group stop + * completion and here. During detach, it would have set + * GROUP_STOP_PENDING on us and we'll re-enter TASK_STOPPED + * in do_signal_stop() on return, so notifying the real + * parent of the group stop completion is enough. */ + if (gstop_done) + do_notify_parent_cldstop(current, false, why); + __set_current_state(TASK_RUNNING); if (clear_code) current->exit_code = 0; @@ -2017,10 +2050,24 @@ relock: spin_unlock_irq(&sighand->siglock); + /* + * Notify the parent that we're continuing. This event is + * always per-process and doesn't make whole lot of sense + * for ptracers, who shouldn't consume the state via + * wait(2) either, but, for backward compatibility, notify + * the ptracer of the group leader too unless it's gonna be + * a duplicate. + */ read_lock(&tasklist_lock); + + do_notify_parent_cldstop(current, false, why); + leader = current->group_leader; - do_notify_parent_cldstop(leader, task_ptrace(leader), why); + if (task_ptrace(leader) && !real_parent_is_ptracer(leader)) + do_notify_parent_cldstop(leader, true, why); + read_unlock(&tasklist_lock); + goto relock; } |