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authorRoland McGrath <roland@redhat.com>2008-07-25 19:45:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-26 12:00:09 -0700
commitb787f7ba677840da16a2228c16571ce8a1fcb799 (patch)
treeb1838c4ae7f38c00efc2375871a255275500f245
parent2b2a1ff64afbadac842bbc58c5166962cf4f7664 (diff)
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>
-rw-r--r--include/linux/tracehook.h14
-rw-r--r--kernel/signal.c4
2 files changed, 17 insertions, 1 deletions
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 4c50e1b5734..43bc51b6bd3 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -423,6 +423,20 @@ static inline int tracehook_consider_fatal_signal(struct task_struct *task,
}
/**
+ * 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
* @regs: task_pt_regs(@current)
diff --git a/kernel/signal.c b/kernel/signal.c
index 0e862d3130f..954f77d7e3b 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -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);
}