linux-kernel - [PATCH -tip v3 2/3] tracepoint: Add signal deliver event

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Date:	Fri, 20 Nov 2009 16:31:21 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, lkml <linux-kernel@...r.kernel.org>
Cc:	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Roland McGrath <roland@...hat.com>,
	Jason Baron <jbaron@...hat.com>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH -tip v3 2/3] tracepoint: Add signal deliver event

Add a tracepoint where a process gets a signal. This tracepoint
shows signal-number, sa-handler and sa-flag.

Changes in v3:
 - Add docbook style comments

Changes in v2:
 - Add siginfo argument
 - Fix comment

Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Roland McGrath <roland@...hat.com>
Cc: Jason Baron <jbaron@...hat.com>
Cc: Ingo Molnar <mingo@...e.hu>
---

 include/trace/events/signal.h |   39 +++++++++++++++++++++++++++++++++++++++
 kernel/signal.c               |    3 +++
 2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
index af2e6b1..ddf89c9 100644
--- a/include/trace/events/signal.h
+++ b/include/trace/events/signal.h
@@ -60,6 +60,45 @@ TRACE_EVENT(signal_generate,
 		  __entry->comm, __entry->pid)
 );
 
+/**
+ * signal_deliver - called when a signal is delivered
+ * @sig: signal number
+ * @info: pointer to struct siginfo
+ * @ka: pointer to struct k_sigaction
+ *
+ * A 'sig' signal is delivered to current process with 'info' siginfo,
+ * and it will be handled by 'ka'. ka->sa.sa_handler can be SIG_IGN or
+ * SIG_DFL.
+ * Note that some signals reported by signal_generate tracepoint can be
+ * lost, ignored or modified (by debugger) before hitting this tracepoint.
+ * This means, this can show which signals are actually delivered, but
+ * matching generated signals and delivered signals may not be correct.
+ */
+TRACE_EVENT(signal_deliver,
+
+	TP_PROTO(int sig, struct siginfo *info, struct k_sigaction *ka),
+
+	TP_ARGS(sig, info, ka),
+
+	TP_STRUCT__entry(
+		__field(	int,		sig		)
+		__field(	int,		errno		)
+		__field(	int,		code		)
+		__field(	unsigned long,	sa_handler	)
+		__field(	unsigned long,	sa_flags	)
+	),
+
+	TP_fast_assign(
+		__entry->sig	= sig;
+		TP_STORE_SIGINFO(__entry, info);
+		__entry->sa_handler	= (unsigned long)ka->sa.sa_handler;
+		__entry->sa_flags	= ka->sa.sa_flags;
+	),
+
+	TP_printk("sig=%d errno=%d code=%d sa_handler=%lx sa_flags=%lx",
+		  __entry->sig, __entry->errno, __entry->code,
+		  __entry->sa_handler, __entry->sa_flags)
+);
 #endif /* _TRACE_SIGNAL_H */
 
 /* This part must be outside protection */
diff --git a/kernel/signal.c b/kernel/signal.c
index 54ac4c5..d518984 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1860,6 +1860,9 @@ relock:
 			ka = &sighand->action[signr-1];
 		}
 
+		/* Trace actually delivered signals. */
+		trace_signal_deliver(signr, info, ka);
+
 		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
 			continue;
 		if (ka->sa.sa_handler != SIG_DFL) {


-- 
Masami Hiramatsu

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

e-mail: mhiramat@...hat.com
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