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Subject[PATCH -tip v2 3/3] tracepoint: Add signal loss events
Date
Add signal_overflow_fail and signal_lose_info tracepoints
for signal-lost events.

Changes in v2:
- Use siginfo string macro

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Suggested-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
---

include/trace/events/signal.h | 52 +++++++++++++++++++++++++++++++++++++++++
kernel/signal.c | 19 +++++++++++----
2 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
index 9a043db..f7215ed 100644
--- a/include/trace/events/signal.h
+++ b/include/trace/events/signal.h
@@ -79,6 +79,58 @@ TRACE_EVENT(signal_deliver,
__entry->sig, __entry->errno, __entry->code,
__entry->sa_handler, __entry->sa_flags)
);
+
+/*
+ * Tracepoint for losing a signal by overflow:
+ */
+TRACE_EVENT(signal_overflow_fail,
+
+ TP_PROTO(int sig, int group, struct siginfo *info),
+
+ TP_ARGS(sig, group, info),
+
+ TP_STRUCT__entry(
+ __field( int, sig )
+ __field( int, group )
+ __field( int, errno )
+ __field( int, code )
+ ),
+
+ TP_fast_assign(
+ __entry->sig = sig;
+ __entry->group = group;
+ TP_STORE_SIGINFO(__entry, info);
+ ),
+
+ TP_printk("sig=%d group=%d errno=%d code=%d",
+ __entry->sig, __entry->group, __entry->errno, __entry->code)
+);
+
+/*
+ * Tracepoint for losing a siginfo:
+ */
+TRACE_EVENT(signal_lose_info,
+
+ TP_PROTO(int sig, int group, struct siginfo *info),
+
+ TP_ARGS(sig, group, info),
+
+ TP_STRUCT__entry(
+ __field( int, sig )
+ __field( int, group )
+ __field( int, errno )
+ __field( int, code )
+ ),
+
+ TP_fast_assign(
+ __entry->sig = sig;
+ __entry->group = group;
+ TP_STORE_SIGINFO(__entry, info);
+ ),
+
+ TP_printk("sig=%d group=%d errno=%d code=%d",
+ __entry->sig, __entry->group, __entry->errno, __entry->code)
+);
#endif /* _TRACE_SIGNAL_H */

/* This part must be outside protection */
diff --git a/kernel/signal.c b/kernel/signal.c
index d518984..6b982f2 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -919,12 +919,21 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
break;
}
} else if (!is_si_special(info)) {
- if (sig >= SIGRTMIN && info->si_code != SI_USER)
- /*
- * Queue overflow, abort. We may abort if the signal was rt
- * and sent by user using something other than kill().
- */
+ if (sig >= SIGRTMIN && info->si_code != SI_USER) {
+ /*
+ * Queue overflow, abort. We may abort if the
+ * signal was rt and sent by user using something
+ * other than kill().
+ */
+ trace_signal_overflow_fail(sig, group, info);
return -EAGAIN;
+ } else {
+ /*
+ * This is a silent loss of information. We still
+ * send the signal, but the *info bits are lost.
+ */
+ trace_signal_lose_info(sig, group, info);
+ }
}

out_set:

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com


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