tracehook: force signal_pending()
This defines a new hook tracehook_force_sigpending() that lets tracing code decide to force TIF_SIGPENDING on in recalc_sigpending(). This is not used yet, so it compiles away to nothing for now. It lays the groundwork for new tracing code that can interrupt a task synthetically without actually sending a signal. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Reviewed-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -422,6 +422,20 @@ static inline int tracehook_consider_fatal_signal(struct task_struct *task,
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return (task_ptrace(task) & PT_PTRACED) != 0;
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}
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/**
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* tracehook_force_sigpending - let tracing force signal_pending(current) on
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*
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* Called when recomputing our signal_pending() flag. Return nonzero
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* to force the signal_pending() flag on, so that tracehook_get_signal()
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* will be called before the next return to user mode.
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*
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* Called with @current->sighand->siglock held.
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*/
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static inline int tracehook_force_sigpending(void)
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{
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return 0;
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}
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/**
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* tracehook_get_signal - deliver synthetic signal to traced task
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* @task: @current
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@ -134,7 +134,9 @@ void recalc_sigpending_and_wake(struct task_struct *t)
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void recalc_sigpending(void)
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{
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if (!recalc_sigpending_tsk(current) && !freezing(current))
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if (unlikely(tracehook_force_sigpending()))
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set_thread_flag(TIF_SIGPENDING);
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else if (!recalc_sigpending_tsk(current) && !freezing(current))
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clear_thread_flag(TIF_SIGPENDING);
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}
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