tracehook: tracehook_consider_ignored_signal

This defines tracehook_consider_ignored_signal() has a fine-grained hook
for deciding to prevent the normal short-circuit of sending an ignored
signal, as ptrace does.  There is no change, only cleanup.

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>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index 2d1426f8e33..8cffd34f88d 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -312,4 +312,23 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info,
                 ptrace_notify(SIGTRAP);
 }
 
+/**
+ * tracehook_consider_ignored_signal - suppress short-circuit of ignored signal
+ * @task:               task receiving the signal
+ * @sig:                signal number being sent
+ * @handler:            %SIG_IGN or %SIG_DFL
+ *
+ * Return zero iff tracing doesn't care to examine this ignored signal,
+ * so it can short-circuit normal delivery and never even get queued.
+ * Either @handler is %SIG_DFL and @sig's default is ignore, or it's %SIG_IGN.
+ *
+ * Called with @task->sighand->siglock held.
+ */
+static inline int tracehook_consider_ignored_signal(struct task_struct *task,
+                                                    int sig,
+                                                    void __user *handler)
+{
+        return (task_ptrace(task) & PT_PTRACED) != 0;
+}
+
 #endif  /* <linux/tracehook.h> */