tracehook: force signal_pending() (b787f7ba) · Commits · 戴 / test

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>

include/linux/tracehook.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -422,6 +422,20 @@ static inline int tracehook_consider_fatal_signal(struct task_struct *task,
		return (task_ptrace(task) & PT_PTRACED) != 0;
		}

		/**
		* tracehook_force_sigpending - let tracing force signal_pending(current) on
		*
		* Called when recomputing our signal_pending() flag. Return nonzero
		* to force the signal_pending() flag on, so that tracehook_get_signal()
		* will be called before the next return to user mode.
		*
		* Called with @current->sighand->siglock held.
		*/
		static inline int tracehook_force_sigpending(void)
		{
		return 0;
		}

		/**
		* tracehook_get_signal - deliver synthetic signal to traced task
		* @task: @current

kernel/signal.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -134,7 +134,9 @@ void recalc_sigpending_and_wake(struct task_struct *t)

		void recalc_sigpending(void)
		{
		if (!recalc_sigpending_tsk(current) && !freezing(current))
		if (unlikely(tracehook_force_sigpending()))
		set_thread_flag(TIF_SIGPENDING);
		else if (!recalc_sigpending_tsk(current) && !freezing(current))
		clear_thread_flag(TIF_SIGPENDING);

		}

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