[PATCH -tip v4 0/3] tracepoint: Add signal events

[PATCH -tip v4 0/3] tracepoint: Add signal events

[Masami Hiramatsu]

Hi,

These patches add signal related tracepoints including
signal generation, delivery, and loss. First patch also
moves signal-sending tracepoint from events/sched.h to
events/signal.h.

Changes in v4
- Fix typo of task_struct pointer

Changes in v3
- Add Docbook style comments

Changes in v2
- Add siginfo arguments

Thank you,

---

Masami Hiramatsu (3):
      tracepoint: Add signal loss events
      tracepoint: Add signal deliver event
      tracepoint: Move signal sending tracepoint to events/signal.h


 Documentation/DocBook/tracepoint.tmpl |    5 +
 include/trace/events/sched.h          |   25 -----
 include/trace/events/signal.h         |  173 +++++++++++++++++++++++++++++++++
 kernel/signal.c                       |   27 ++++-
 4 files changed, 198 insertions(+), 32 deletions(-)
 create mode 100644 include/trace/events/signal.h

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com

[PATCH -tip v4 1/3] tracepoint: Move signal sending tracepoint to events/signal.h

[Masami Hiramatsu]

Move signal sending event to events/signal.h. This patch also renames
sched_signal_send event to signal_generate.

Changes in v4:
 - Fix a typo of task_struct pointer.

Changes in v3:
 - Add docbook style comments

Changes in v2:
 - Add siginfo argument
 - Add siginfo storing macro

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

 Documentation/DocBook/tracepoint.tmpl |    5 +++
 include/trace/events/sched.h          |   25 -------------
 include/trace/events/signal.h         |   66 +++++++++++++++++++++++++++++++++
 kernel/signal.c                       |    5 ++-
 4 files changed, 74 insertions(+), 27 deletions(-)
 create mode 100644 include/trace/events/signal.h

diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
index b0756d0..8bca1d5 100644
--- a/Documentation/DocBook/tracepoint.tmpl
+++ b/Documentation/DocBook/tracepoint.tmpl
@@ -86,4 +86,9 @@
 !Iinclude/trace/events/irq.h
   </chapter>
 
+  <chapter id="signal">
+   <title>SIGNAL</title>
+!Iinclude/trace/events/signal.h
+  </chapter>
+
 </book>
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index b50b985..b221bb3 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -320,31 +320,6 @@ TRACE_EVENT(sched_process_fork,
 );
 
 /*
- * Tracepoint for sending a signal:
- */
-TRACE_EVENT(sched_signal_send,
-
-	TP_PROTO(int sig, struct task_struct *p),
-
-	TP_ARGS(sig, p),
-
-	TP_STRUCT__entry(
-		__field(	int,	sig			)
-		__array(	char,	comm,	TASK_COMM_LEN	)
-		__field(	pid_t,	pid			)
-	),
-
-	TP_fast_assign(
-		memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
-		__entry->pid	= p->pid;
-		__entry->sig	= sig;
-	),
-
-	TP_printk("sig=%d comm=%s pid=%d",
-		  __entry->sig, __entry->comm, __entry->pid)
-);
-
-/*
  * XXX the below sched_stat tracepoints only apply to SCHED_OTHER/BATCH/IDLE
  *     adding sched_stat support to SCHED_FIFO/RR would be welcome.
  */
diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
new file mode 100644
index 0000000..ef51756
--- /dev/null
+++ b/include/trace/events/signal.h
@@ -0,0 +1,66 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM signal
+
+#if !defined(_TRACE_SIGNAL_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SIGNAL_H
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/tracepoint.h>
+
+#define TP_STORE_SIGINFO(__entry, info)				\
+	do {							\
+		if (info == SEND_SIG_NOINFO) {			\
+			__entry->errno	= 0;			\
+			__entry->code	= SI_USER;		\
+		} else if (info == SEND_SIG_PRIV) {		\
+			__entry->errno	= 0;			\
+			__entry->code	= SI_KERNEL;		\
+		} else {					\
+			__entry->errno	= info->si_errno;	\
+			__entry->code	= info->si_code;	\
+		}						\
+	} while (0)
+
+/**
+ * signal_generate - called when a signal is generated
+ * @sig: signal number
+ * @info: pointer to struct siginfo
+ * @task: pointer to struct task_struct
+ *
+ * Current process sends a 'sig' signal to 'task' process with
+ * 'info' siginfo. If 'info' is SEND_SIG_NOINFO or SEND_SIG_PRIV,
+ * 'info' is not a pointer and you can't access its field. Instead,
+ * SEND_SIG_NOINFO means that si_code is SI_USER, and SEND_SIG_PRIV
+ * means that si_code is SI_KERNEL.
+ */
+TRACE_EVENT(signal_generate,
+
+	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task),
+
+	TP_ARGS(sig, info, task),
+
+	TP_STRUCT__entry(
+		__field(	int,	sig			)
+		__field(	int,	errno			)
+		__field(	int,	code			)
+		__array(	char,	comm,	TASK_COMM_LEN	)
+		__field(	pid_t,	pid			)
+	),
+
+	TP_fast_assign(
+		__entry->sig	= sig;
+		TP_STORE_SIGINFO(__entry, info);
+		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+		__entry->pid	= task->pid;
+	),
+
+	TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d",
+		  __entry->sig, __entry->errno, __entry->code,
+		  __entry->comm, __entry->pid)
+);
+
+#endif /* _TRACE_SIGNAL_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/signal.c b/kernel/signal.c
index fe08008..54ac4c5 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -28,7 +28,8 @@
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
 #include <linux/nsproxy.h>
-#include <trace/events/sched.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/signal.h>
 
 #include <asm/param.h>
 #include <asm/uaccess.h>
@@ -856,7 +857,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 	struct sigqueue *q;
 	int override_rlimit;
 
-	trace_sched_signal_send(sig, t);
+	trace_signal_generate(sig, info, t);
 
 	assert_spin_locked(&t->sighand->siglock);
 


-- 
Masami Hiramatsu

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

e-mail: mhiramat@redhat.com

[PATCH -tip v4 2/3] tracepoint: Add signal deliver event

[Masami Hiramatsu]

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@redhat.com>
Reviewed-by: Jason Baron <jbaron@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.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 ef51756..a6d71de 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@redhat.com

[PATCH -tip v4 3/3] tracepoint: Add signal loss events

[Masami Hiramatsu]

Add signal_overflow_fail and signal_lose_info tracepoints
for signal-lost events.

Changes in v3:
 - Add docbook style comments

Changes in v2:
 - Use siginfo string macro

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

 include/trace/events/signal.h |   68 +++++++++++++++++++++++++++++++++++++++++
 kernel/signal.c               |   19 ++++++++---
 2 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
index a6d71de..a510b75 100644
--- a/include/trace/events/signal.h
+++ b/include/trace/events/signal.h
@@ -99,6 +99,74 @@ TRACE_EVENT(signal_deliver,
 		  __entry->sig, __entry->errno, __entry->code,
 		  __entry->sa_handler, __entry->sa_flags)
 );
+
+/**
+ * signal_overflow_fail - called when signal queue is overflow
+ * @sig: signal number
+ * @group: signal to process group or not (bool)
+ * @info: pointer to struct siginfo
+ *
+ * Kernel fails to generate 'sig' signal with 'info' siginfo, because
+ * siginfo queue is overflow, and the signal is dropped.
+ * 'group' is not 0 if the signal will be sent to a process group.
+ * 'sig' is always one of RT signals.
+ */
+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)
+);
+
+/**
+ * signal_lose_info - called when siginfo is lost
+ * @sig: signal number
+ * @group: signal to process group or not (bool)
+ * @info: pointer to struct siginfo
+ *
+ * Kernel generates 'sig' signal but loses 'info' siginfo, because siginfo
+ * queue is overflow.
+ * 'group' is not 0 if the signal will be sent to a process group.
+ * 'sig' is always one of non-RT signals.
+ */
+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

Re: [PATCH -tip v4 0/3] tracepoint: Add signal events

[Roland McGrath]

Acked-by: Roland McGrath <roland@redhat.com>

There might be some more refinements that are worthwhile, but these look
like a sensible and clean enough set of tracepoints to start with.  If we
need to change them, that will become clear from the experiences of people
actually using these.


Thanks,
Roland

[tip:perf/core] tracepoint: Move signal sending tracepoint to events/signal.h

[tip-bot for Masami Hiramatsu]

Commit-ID:  d1eb650ff4130972fa21462fa49cd35a2865403b
Gitweb:     http://git.kernel.org/tip/d1eb650ff4130972fa21462fa49cd35a2865403b
Author:     Masami Hiramatsu <mhiramat@redhat.com>
AuthorDate: Tue, 24 Nov 2009 16:56:45 -0500
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 26 Nov 2009 10:55:37 +0100

tracepoint: Move signal sending tracepoint to events/signal.h

Move signal sending event to events/signal.h. This patch also
renames sched_signal_send event to signal_generate.

Changes in v4:
 - Fix a typo of task_struct pointer.

Changes in v3:
 - Add docbook style comments

Changes in v2:
 - Add siginfo argument
 - Add siginfo storing macro

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Reviewed-by: Jason Baron <jbaron@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Oleg Nesterov <oleg@redhat.com>
LKML-Reference: <20091124215645.30449.60208.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 Documentation/DocBook/tracepoint.tmpl |    5 ++
 include/trace/events/sched.h          |   25 ------------
 include/trace/events/signal.h         |   66 +++++++++++++++++++++++++++++++++
 kernel/signal.c                       |    5 +-
 4 files changed, 74 insertions(+), 27 deletions(-)

diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
index b0756d0..8bca1d5 100644
--- a/Documentation/DocBook/tracepoint.tmpl
+++ b/Documentation/DocBook/tracepoint.tmpl
@@ -86,4 +86,9 @@
 !Iinclude/trace/events/irq.h
   </chapter>
 
+  <chapter id="signal">
+   <title>SIGNAL</title>
+!Iinclude/trace/events/signal.h
+  </chapter>
+
 </book>
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 9d316b2..cfceb0b 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -288,31 +288,6 @@ TRACE_EVENT(sched_process_fork,
 );
 
 /*
- * Tracepoint for sending a signal:
- */
-TRACE_EVENT(sched_signal_send,
-
-	TP_PROTO(int sig, struct task_struct *p),
-
-	TP_ARGS(sig, p),
-
-	TP_STRUCT__entry(
-		__field(	int,	sig			)
-		__array(	char,	comm,	TASK_COMM_LEN	)
-		__field(	pid_t,	pid			)
-	),
-
-	TP_fast_assign(
-		memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
-		__entry->pid	= p->pid;
-		__entry->sig	= sig;
-	),
-
-	TP_printk("sig=%d comm=%s pid=%d",
-		  __entry->sig, __entry->comm, __entry->pid)
-);
-
-/*
  * XXX the below sched_stat tracepoints only apply to SCHED_OTHER/BATCH/IDLE
  *     adding sched_stat support to SCHED_FIFO/RR would be welcome.
  */
diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
new file mode 100644
index 0000000..ef51756
--- /dev/null
+++ b/include/trace/events/signal.h
@@ -0,0 +1,66 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM signal
+
+#if !defined(_TRACE_SIGNAL_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SIGNAL_H
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/tracepoint.h>
+
+#define TP_STORE_SIGINFO(__entry, info)				\
+	do {							\
+		if (info == SEND_SIG_NOINFO) {			\
+			__entry->errno	= 0;			\
+			__entry->code	= SI_USER;		\
+		} else if (info == SEND_SIG_PRIV) {		\
+			__entry->errno	= 0;			\
+			__entry->code	= SI_KERNEL;		\
+		} else {					\
+			__entry->errno	= info->si_errno;	\
+			__entry->code	= info->si_code;	\
+		}						\
+	} while (0)
+
+/**
+ * signal_generate - called when a signal is generated
+ * @sig: signal number
+ * @info: pointer to struct siginfo
+ * @task: pointer to struct task_struct
+ *
+ * Current process sends a 'sig' signal to 'task' process with
+ * 'info' siginfo. If 'info' is SEND_SIG_NOINFO or SEND_SIG_PRIV,
+ * 'info' is not a pointer and you can't access its field. Instead,
+ * SEND_SIG_NOINFO means that si_code is SI_USER, and SEND_SIG_PRIV
+ * means that si_code is SI_KERNEL.
+ */
+TRACE_EVENT(signal_generate,
+
+	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task),
+
+	TP_ARGS(sig, info, task),
+
+	TP_STRUCT__entry(
+		__field(	int,	sig			)
+		__field(	int,	errno			)
+		__field(	int,	code			)
+		__array(	char,	comm,	TASK_COMM_LEN	)
+		__field(	pid_t,	pid			)
+	),
+
+	TP_fast_assign(
+		__entry->sig	= sig;
+		TP_STORE_SIGINFO(__entry, info);
+		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
+		__entry->pid	= task->pid;
+	),
+
+	TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d",
+		  __entry->sig, __entry->errno, __entry->code,
+		  __entry->comm, __entry->pid)
+);
+
+#endif /* _TRACE_SIGNAL_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/kernel/signal.c b/kernel/signal.c
index 6705320..a1e0cc6 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -27,7 +27,8 @@
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
 #include <linux/nsproxy.h>
-#include <trace/events/sched.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/signal.h>
 
 #include <asm/param.h>
 #include <asm/uaccess.h>
@@ -834,7 +835,7 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 	struct sigqueue *q;
 	int override_rlimit;
 
-	trace_sched_signal_send(sig, t);
+	trace_signal_generate(sig, info, t);
 
 	assert_spin_locked(&t->sighand->siglock);
 

[tip:perf/core] tracepoint: Add signal loss events

[tip-bot for Masami Hiramatsu]

Commit-ID:  ba005e1f417295d28cd1563ab82bc33af07fb16a
Gitweb:     http://git.kernel.org/tip/ba005e1f417295d28cd1563ab82bc33af07fb16a
Author:     Masami Hiramatsu <mhiramat@redhat.com>
AuthorDate: Tue, 24 Nov 2009 16:56:58 -0500
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 26 Nov 2009 10:55:38 +0100

tracepoint: Add signal loss events

Add signal_overflow_fail and signal_lose_info tracepoints
for signal-lost events.

Changes in v3:
 - Add docbook style comments

Changes in v2:
 - Use siginfo string macro

Suggested-by: Roland McGrath <roland@redhat.com>
Reviewed-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Oleg Nesterov <oleg@redhat.com>
LKML-Reference: <20091124215658.30449.9934.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/trace/events/signal.h |   68 +++++++++++++++++++++++++++++++++++++++++
 kernel/signal.c               |   19 ++++++++---
 2 files changed, 82 insertions(+), 5 deletions(-)

diff --git a/include/trace/events/signal.h b/include/trace/events/signal.h
index a6d71de..a510b75 100644
--- a/include/trace/events/signal.h
+++ b/include/trace/events/signal.h
@@ -99,6 +99,74 @@ TRACE_EVENT(signal_deliver,
 		  __entry->sig, __entry->errno, __entry->code,
 		  __entry->sa_handler, __entry->sa_flags)
 );
+
+/**
+ * signal_overflow_fail - called when signal queue is overflow
+ * @sig: signal number
+ * @group: signal to process group or not (bool)
+ * @info: pointer to struct siginfo
+ *
+ * Kernel fails to generate 'sig' signal with 'info' siginfo, because
+ * siginfo queue is overflow, and the signal is dropped.
+ * 'group' is not 0 if the signal will be sent to a process group.
+ * 'sig' is always one of RT signals.
+ */
+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)
+);
+
+/**
+ * signal_lose_info - called when siginfo is lost
+ * @sig: signal number
+ * @group: signal to process group or not (bool)
+ * @info: pointer to struct siginfo
+ *
+ * Kernel generates 'sig' signal but loses 'info' siginfo, because siginfo
+ * queue is overflow.
+ * 'group' is not 0 if the signal will be sent to a process group.
+ * 'sig' is always one of non-RT signals.
+ */
+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 349d449..93e72e5 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -897,12 +897,21 @@ 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:

[tip:perf/core] tracepoint: Add signal deliver event

[tip-bot for Masami Hiramatsu]

Commit-ID:  f9d4257e01d266e67420cc99d456b6d4c8464f54
Gitweb:     http://git.kernel.org/tip/f9d4257e01d266e67420cc99d456b6d4c8464f54
Author:     Masami Hiramatsu <mhiramat@redhat.com>
AuthorDate: Tue, 24 Nov 2009 16:56:51 -0500
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 26 Nov 2009 10:55:38 +0100

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@redhat.com>
Reviewed-by: Jason Baron <jbaron@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Oleg Nesterov <oleg@redhat.com>
LKML-Reference: <20091124215651.30449.20926.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.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 ef51756..a6d71de 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 a1e0cc6..349d449 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1840,6 +1840,9 @@ 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) {