From 745b1626dd71ce9661a05ea4db57859ed5c773d2 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Thu, 15 Jan 2009 23:40:11 -0500
Subject: trace: set max latency variable to zero on default

Impact: trace max latencies on start of latency tracing

This patch sets the max latency to zero whenever one of the
irq variant tracers or the wakeup tracer is set to current tracer.

Most developers expect to see output when starting up a latency
tracer. But since the max_latency is already set to max, and
it takes a latency greater than max_latency to be recorded, there
is no trace. This is not the expected behavior and has even confused
myself.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace_sched_wakeup.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 43586b689e3..42ae1e77b6b 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -333,6 +333,7 @@ static void stop_wakeup_tracer(struct trace_array *tr)
 
 static int wakeup_tracer_init(struct trace_array *tr)
 {
+	tracing_max_latency = 0;
 	wakeup_trace = tr;
 	start_wakeup_tracer(tr);
 	return 0;
-- 
cgit v1.2.3-70-g09d2


From 5bc4564b224c3d9fe6dddafa25f56059bd978231 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 21 Jan 2009 14:36:52 -0500
Subject: trace: do not disable wake up tracer on output of trace

Impact: fix to erased trace output

To try not to have the outputing of a trace interfere with the wakeup
tracer, it would disable tracing while the output was printing. But
if a trace had started when it was disabled, it can show a partial
trace. To try to solve this, on closing of the tracer, it would
clear the trace buffer.

The latency tracers (wakeup and irqsoff) have two buffers. One for
recording and one for holding the max trace that is printed. The
clearing of the trace above should only affect the recording buffer.
But for some reason it would move the erased trace to the print
buffer. Probably due to a race with the closing of the trace and
the saving ofhe max race.

The above is all pretty useless, and if the user does not want the
printing of the trace to be traced itself, then the user can manual
disable tracing. This patch removes all the code that tries to keep
the output of the tracer from modifying the trace.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace_sched_wakeup.c | 33 ++-------------------------------
 1 file changed, 2 insertions(+), 31 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 42ae1e77b6b..e27adef0171 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -262,12 +262,6 @@ out:
 	atomic_dec(&wakeup_trace->data[cpu]->disabled);
 }
 
-/*
- * save_tracer_enabled is used to save the state of the tracer_enabled
- * variable when we disable it when we open a trace output file.
- */
-static int save_tracer_enabled;
-
 static void start_wakeup_tracer(struct trace_array *tr)
 {
 	int ret;
@@ -306,13 +300,10 @@ static void start_wakeup_tracer(struct trace_array *tr)
 
 	register_ftrace_function(&trace_ops);
 
-	if (tracing_is_enabled()) {
+	if (tracing_is_enabled())
 		tracer_enabled = 1;
-		save_tracer_enabled = 1;
-	} else {
+	else
 		tracer_enabled = 0;
-		save_tracer_enabled = 0;
-	}
 
 	return;
 fail_deprobe_wake_new:
@@ -324,7 +315,6 @@ fail_deprobe:
 static void stop_wakeup_tracer(struct trace_array *tr)
 {
 	tracer_enabled = 0;
-	save_tracer_enabled = 0;
 	unregister_ftrace_function(&trace_ops);
 	unregister_trace_sched_switch(probe_wakeup_sched_switch);
 	unregister_trace_sched_wakeup_new(probe_wakeup);
@@ -350,28 +340,11 @@ static void wakeup_tracer_start(struct trace_array *tr)
 {
 	wakeup_reset(tr);
 	tracer_enabled = 1;
-	save_tracer_enabled = 1;
 }
 
 static void wakeup_tracer_stop(struct trace_array *tr)
 {
 	tracer_enabled = 0;
-	save_tracer_enabled = 0;
-}
-
-static void wakeup_tracer_open(struct trace_iterator *iter)
-{
-	/* stop the trace while dumping */
-	tracer_enabled = 0;
-}
-
-static void wakeup_tracer_close(struct trace_iterator *iter)
-{
-	/* forget about any processes we were recording */
-	if (save_tracer_enabled) {
-		wakeup_reset(iter->tr);
-		tracer_enabled = 1;
-	}
 }
 
 static struct tracer wakeup_tracer __read_mostly =
@@ -381,8 +354,6 @@ static struct tracer wakeup_tracer __read_mostly =
 	.reset		= wakeup_tracer_reset,
 	.start		= wakeup_tracer_start,
 	.stop		= wakeup_tracer_stop,
-	.open		= wakeup_tracer_open,
-	.close		= wakeup_tracer_close,
 	.print_max	= 1,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_wakeup,
-- 
cgit v1.2.3-70-g09d2


From 3244351c31211a8b1ba8b4b34c3de04d5dfa03e4 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 21 Jan 2009 16:24:46 -0500
Subject: trace: separate out rt tasks from wakeup tracer

Impact: add option to trace all tasks or just RT tasks

The current wakeup tracer only traces RT task wakeups. This is
fine for those interested in wake up timings of RT tasks, but
it is useless for those that are interested in the causes
of long wakeups for non RT tasks.

This patch creates a "wakeup_rt" to implement the tracing of just
RT tasks (as the current "wakeup" does). And makes "wakeup" now
trace all tasks as an average developer would expect.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace_sched_wakeup.c | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index e27adef0171..f4895788610 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -25,6 +25,7 @@ static int __read_mostly	tracer_enabled;
 static struct task_struct	*wakeup_task;
 static int			wakeup_cpu;
 static unsigned			wakeup_prio = -1;
+static int			wakeup_rt;
 
 static raw_spinlock_t wakeup_lock =
 	(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
@@ -224,7 +225,7 @@ probe_wakeup(struct rq *rq, struct task_struct *p, int success)
 	tracing_record_cmdline(p);
 	tracing_record_cmdline(current);
 
-	if (likely(!rt_task(p)) ||
+	if ((wakeup_rt && !rt_task(p)) ||
 			p->prio >= wakeup_prio ||
 			p->prio >= current->prio)
 		return;
@@ -321,7 +322,7 @@ static void stop_wakeup_tracer(struct trace_array *tr)
 	unregister_trace_sched_wakeup(probe_wakeup);
 }
 
-static int wakeup_tracer_init(struct trace_array *tr)
+static int __wakeup_tracer_init(struct trace_array *tr)
 {
 	tracing_max_latency = 0;
 	wakeup_trace = tr;
@@ -329,6 +330,18 @@ static int wakeup_tracer_init(struct trace_array *tr)
 	return 0;
 }
 
+static int wakeup_tracer_init(struct trace_array *tr)
+{
+	wakeup_rt = 0;
+	return __wakeup_tracer_init(tr);
+}
+
+static int wakeup_rt_tracer_init(struct trace_array *tr)
+{
+	wakeup_rt = 1;
+	return __wakeup_tracer_init(tr);
+}
+
 static void wakeup_tracer_reset(struct trace_array *tr)
 {
 	stop_wakeup_tracer(tr);
@@ -360,6 +373,19 @@ static struct tracer wakeup_tracer __read_mostly =
 #endif
 };
 
+static struct tracer wakeup_rt_tracer __read_mostly =
+{
+	.name		= "wakeup_rt",
+	.init		= wakeup_rt_tracer_init,
+	.reset		= wakeup_tracer_reset,
+	.start		= wakeup_tracer_start,
+	.stop		= wakeup_tracer_stop,
+	.print_max	= 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_wakeup,
+#endif
+};
+
 __init static int init_wakeup_tracer(void)
 {
 	int ret;
@@ -368,6 +394,10 @@ __init static int init_wakeup_tracer(void)
 	if (ret)
 		return ret;
 
+	ret = register_tracer(&wakeup_rt_tracer);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 device_initcall(init_wakeup_tracer);
-- 
cgit v1.2.3-70-g09d2


From f8ec1062f589cdb1cffcffab1376124a1bc08500 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 21 Jan 2009 17:17:04 -0500
Subject: wakeup-tracer: show scheduling data in output

Impact: better data for wakeup tracer

This patch adds the wakeup and schedule calls that are used by
the scheduler tracer to make the wakeup tracer more readable.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace_sched_wakeup.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index f4895788610..93cecda650b 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -153,6 +153,7 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
 		goto out_unlock;
 
 	trace_function(wakeup_trace, data, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
+	tracing_sched_switch_trace(wakeup_trace, data, prev, next, flags, pc);
 
 	/*
 	 * usecs conversion is slow so we try to delay the conversion
@@ -214,6 +215,7 @@ static void wakeup_reset(struct trace_array *tr)
 static void
 probe_wakeup(struct rq *rq, struct task_struct *p, int success)
 {
+	struct trace_array_cpu *data;
 	int cpu = smp_processor_id();
 	unsigned long flags;
 	long disabled;
@@ -253,9 +255,12 @@ probe_wakeup(struct rq *rq, struct task_struct *p, int success)
 
 	local_save_flags(flags);
 
-	wakeup_trace->data[wakeup_cpu]->preempt_timestamp = ftrace_now(cpu);
-	trace_function(wakeup_trace, wakeup_trace->data[wakeup_cpu],
-		       CALLER_ADDR1, CALLER_ADDR2, flags, pc);
+	data = wakeup_trace->data[wakeup_cpu];
+	data->preempt_timestamp = ftrace_now(cpu);
+	tracing_sched_wakeup_trace(wakeup_trace, data, p, current,
+				   flags, pc);
+	trace_function(wakeup_trace, data, CALLER_ADDR1, CALLER_ADDR2,
+		       flags, pc);
 
 out_locked:
 	__raw_spin_unlock(&wakeup_lock);
-- 
cgit v1.2.3-70-g09d2


From b3a8c34886d0e3dd3a24a5b614ee025181da2f41 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Wed, 28 Jan 2009 13:08:37 -0200
Subject: trace_sched_wakeup: Remove unused variable

Impact: cleanup

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace_sched_wakeup.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 93cecda650b..a48c9b4b0c8 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -184,13 +184,10 @@ out:
 
 static void __wakeup_reset(struct trace_array *tr)
 {
-	struct trace_array_cpu *data;
 	int cpu;
 
-	for_each_possible_cpu(cpu) {
-		data = tr->data[cpu];
+	for_each_possible_cpu(cpu)
 		tracing_reset(tr, cpu);
-	}
 
 	wakeup_cpu = -1;
 	wakeup_prio = -1;
-- 
cgit v1.2.3-70-g09d2


From 7be421510b91491d5aa5a29fa1005712039b95af Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Thu, 5 Feb 2009 01:13:37 -0500
Subject: trace: Remove unused trace_array_cpu parameter

Impact: cleanup

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 block/blktrace.c                  |  2 +-
 kernel/trace/trace.c              | 47 +++++++++++++++------------------------
 kernel/trace/trace.h              |  4 ----
 kernel/trace/trace_functions.c    |  8 +++----
 kernel/trace/trace_irqsoff.c      | 10 ++++-----
 kernel/trace/trace_sched_switch.c |  4 ++--
 kernel/trace/trace_sched_wakeup.c | 12 +++++-----
 7 files changed, 35 insertions(+), 52 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/block/blktrace.c b/block/blktrace.c
index 1ebd068061e..d9d7146ee02 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -245,7 +245,7 @@ record_it:
 			if (pid != 0 &&
 			    !(blk_tracer_flags.val & TRACE_BLK_OPT_CLASSIC) &&
 			    (trace_flags & TRACE_ITER_STACKTRACE) != 0)
-				__trace_stack(blk_tr, NULL, flags, 5, pc);
+				__trace_stack(blk_tr, flags, 5, pc);
 			trace_wake_up();
 			return;
 		}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a5e4c0af9bb..1d4ff568cc4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -776,7 +776,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
 }
 
 void
-trace_function(struct trace_array *tr, struct trace_array_cpu *data,
+trace_function(struct trace_array *tr,
 	       unsigned long ip, unsigned long parent_ip, unsigned long flags,
 	       int pc)
 {
@@ -802,7 +802,6 @@ trace_function(struct trace_array *tr, struct trace_array_cpu *data,
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static void __trace_graph_entry(struct trace_array *tr,
-				struct trace_array_cpu *data,
 				struct ftrace_graph_ent *trace,
 				unsigned long flags,
 				int pc)
@@ -826,7 +825,6 @@ static void __trace_graph_entry(struct trace_array *tr,
 }
 
 static void __trace_graph_return(struct trace_array *tr,
-				struct trace_array_cpu *data,
 				struct ftrace_graph_ret *trace,
 				unsigned long flags,
 				int pc)
@@ -856,11 +854,10 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data,
        int pc)
 {
 	if (likely(!atomic_read(&data->disabled)))
-		trace_function(tr, data, ip, parent_ip, flags, pc);
+		trace_function(tr, ip, parent_ip, flags, pc);
 }
 
 static void __ftrace_trace_stack(struct trace_array *tr,
-				 struct trace_array_cpu *data,
 				 unsigned long flags,
 				 int skip, int pc)
 {
@@ -891,27 +888,24 @@ static void __ftrace_trace_stack(struct trace_array *tr,
 }
 
 static void ftrace_trace_stack(struct trace_array *tr,
-			       struct trace_array_cpu *data,
 			       unsigned long flags,
 			       int skip, int pc)
 {
 	if (!(trace_flags & TRACE_ITER_STACKTRACE))
 		return;
 
-	__ftrace_trace_stack(tr, data, flags, skip, pc);
+	__ftrace_trace_stack(tr, flags, skip, pc);
 }
 
 void __trace_stack(struct trace_array *tr,
-		   struct trace_array_cpu *data,
 		   unsigned long flags,
 		   int skip, int pc)
 {
-	__ftrace_trace_stack(tr, data, flags, skip, pc);
+	__ftrace_trace_stack(tr, flags, skip, pc);
 }
 
 static void ftrace_trace_userstack(struct trace_array *tr,
-		   struct trace_array_cpu *data,
-		   unsigned long flags, int pc)
+				   unsigned long flags, int pc)
 {
 #ifdef CONFIG_STACKTRACE
 	struct ring_buffer_event *event;
@@ -942,20 +936,17 @@ static void ftrace_trace_userstack(struct trace_array *tr,
 #endif
 }
 
-void __trace_userstack(struct trace_array *tr,
-		   struct trace_array_cpu *data,
-		   unsigned long flags)
+void __trace_userstack(struct trace_array *tr, unsigned long flags)
 {
-	ftrace_trace_userstack(tr, data, flags, preempt_count());
+	ftrace_trace_userstack(tr, flags, preempt_count());
 }
 
 static void
-ftrace_trace_special(void *__tr, void *__data,
+ftrace_trace_special(void *__tr,
 		     unsigned long arg1, unsigned long arg2, unsigned long arg3,
 		     int pc)
 {
 	struct ring_buffer_event *event;
-	struct trace_array_cpu *data = __data;
 	struct trace_array *tr = __tr;
 	struct special_entry *entry;
 	unsigned long irq_flags;
@@ -971,8 +962,8 @@ ftrace_trace_special(void *__tr, void *__data,
 	entry->arg2			= arg2;
 	entry->arg3			= arg3;
 	ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
-	ftrace_trace_stack(tr, data, irq_flags, 4, pc);
-	ftrace_trace_userstack(tr, data, irq_flags, pc);
+	ftrace_trace_stack(tr, irq_flags, 4, pc);
+	ftrace_trace_userstack(tr, irq_flags, pc);
 
 	trace_wake_up();
 }
@@ -981,12 +972,11 @@ void
 __trace_special(void *__tr, void *__data,
 		unsigned long arg1, unsigned long arg2, unsigned long arg3)
 {
-	ftrace_trace_special(__tr, __data, arg1, arg2, arg3, preempt_count());
+	ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
 }
 
 void
 tracing_sched_switch_trace(struct trace_array *tr,
-			   struct trace_array_cpu *data,
 			   struct task_struct *prev,
 			   struct task_struct *next,
 			   unsigned long flags, int pc)
@@ -1010,13 +1000,12 @@ tracing_sched_switch_trace(struct trace_array *tr,
 	entry->next_state		= next->state;
 	entry->next_cpu	= task_cpu(next);
 	ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
-	ftrace_trace_stack(tr, data, flags, 5, pc);
-	ftrace_trace_userstack(tr, data, flags, pc);
+	ftrace_trace_stack(tr, flags, 5, pc);
+	ftrace_trace_userstack(tr, flags, pc);
 }
 
 void
 tracing_sched_wakeup_trace(struct trace_array *tr,
-			   struct trace_array_cpu *data,
 			   struct task_struct *wakee,
 			   struct task_struct *curr,
 			   unsigned long flags, int pc)
@@ -1040,8 +1029,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
 	entry->next_state		= wakee->state;
 	entry->next_cpu			= task_cpu(wakee);
 	ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
-	ftrace_trace_stack(tr, data, flags, 6, pc);
-	ftrace_trace_userstack(tr, data, flags, pc);
+	ftrace_trace_stack(tr, flags, 6, pc);
+	ftrace_trace_userstack(tr, flags, pc);
 
 	trace_wake_up();
 }
@@ -1064,7 +1053,7 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
 	data = tr->data[cpu];
 
 	if (likely(atomic_inc_return(&data->disabled) == 1))
-		ftrace_trace_special(tr, data, arg1, arg2, arg3, pc);
+		ftrace_trace_special(tr, arg1, arg2, arg3, pc);
 
 	atomic_dec(&data->disabled);
 	local_irq_restore(flags);
@@ -1092,7 +1081,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
 	disabled = atomic_inc_return(&data->disabled);
 	if (likely(disabled == 1)) {
 		pc = preempt_count();
-		__trace_graph_entry(tr, data, trace, flags, pc);
+		__trace_graph_entry(tr, trace, flags, pc);
 	}
 	/* Only do the atomic if it is not already set */
 	if (!test_tsk_trace_graph(current))
@@ -1118,7 +1107,7 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
 	disabled = atomic_inc_return(&data->disabled);
 	if (likely(disabled == 1)) {
 		pc = preempt_count();
-		__trace_graph_return(tr, data, trace, flags, pc);
+		__trace_graph_return(tr, trace, flags, pc);
 	}
 	if (!trace->depth)
 		clear_tsk_trace_graph(current);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f0c7a0f08ca..df627a94869 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -419,14 +419,12 @@ void ftrace(struct trace_array *tr,
 			    unsigned long parent_ip,
 			    unsigned long flags, int pc);
 void tracing_sched_switch_trace(struct trace_array *tr,
-				struct trace_array_cpu *data,
 				struct task_struct *prev,
 				struct task_struct *next,
 				unsigned long flags, int pc);
 void tracing_record_cmdline(struct task_struct *tsk);
 
 void tracing_sched_wakeup_trace(struct trace_array *tr,
-				struct trace_array_cpu *data,
 				struct task_struct *wakee,
 				struct task_struct *cur,
 				unsigned long flags, int pc);
@@ -436,7 +434,6 @@ void trace_special(struct trace_array *tr,
 		   unsigned long arg2,
 		   unsigned long arg3, int pc);
 void trace_function(struct trace_array *tr,
-		    struct trace_array_cpu *data,
 		    unsigned long ip,
 		    unsigned long parent_ip,
 		    unsigned long flags, int pc);
@@ -462,7 +459,6 @@ void update_max_tr_single(struct trace_array *tr,
 			  struct task_struct *tsk, int cpu);
 
 void __trace_stack(struct trace_array *tr,
-		   struct trace_array_cpu *data,
 		   unsigned long flags,
 		   int skip, int pc);
 
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index b3a320f8aba..d067cea2ccc 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -78,7 +78,7 @@ function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
 	disabled = atomic_inc_return(&data->disabled);
 
 	if (likely(disabled == 1))
-		trace_function(tr, data, ip, parent_ip, flags, pc);
+		trace_function(tr, ip, parent_ip, flags, pc);
 
 	atomic_dec(&data->disabled);
 	ftrace_preempt_enable(resched);
@@ -108,7 +108,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
 
 	if (likely(disabled == 1)) {
 		pc = preempt_count();
-		trace_function(tr, data, ip, parent_ip, flags, pc);
+		trace_function(tr, ip, parent_ip, flags, pc);
 	}
 
 	atomic_dec(&data->disabled);
@@ -139,7 +139,7 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
 
 	if (likely(disabled == 1)) {
 		pc = preempt_count();
-		trace_function(tr, data, ip, parent_ip, flags, pc);
+		trace_function(tr, ip, parent_ip, flags, pc);
 		/*
 		 * skip over 5 funcs:
 		 *    __ftrace_trace_stack,
@@ -148,7 +148,7 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
 		 *    ftrace_list_func
 		 *    ftrace_call
 		 */
-		__trace_stack(tr, data, flags, 5, pc);
+		__trace_stack(tr, flags, 5, pc);
 	}
 
 	atomic_dec(&data->disabled);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index ed344b022a1..c6b442d88de 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -95,7 +95,7 @@ irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
 	disabled = atomic_inc_return(&data->disabled);
 
 	if (likely(disabled == 1))
-		trace_function(tr, data, ip, parent_ip, flags, preempt_count());
+		trace_function(tr, ip, parent_ip, flags, preempt_count());
 
 	atomic_dec(&data->disabled);
 }
@@ -153,7 +153,7 @@ check_critical_timing(struct trace_array *tr,
 	if (!report_latency(delta))
 		goto out_unlock;
 
-	trace_function(tr, data, CALLER_ADDR0, parent_ip, flags, pc);
+	trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
 
 	latency = nsecs_to_usecs(delta);
 
@@ -177,7 +177,7 @@ out:
 	data->critical_sequence = max_sequence;
 	data->preempt_timestamp = ftrace_now(cpu);
 	tracing_reset(tr, cpu);
-	trace_function(tr, data, CALLER_ADDR0, parent_ip, flags, pc);
+	trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
 }
 
 static inline void
@@ -210,7 +210,7 @@ start_critical_timing(unsigned long ip, unsigned long parent_ip)
 
 	local_save_flags(flags);
 
-	trace_function(tr, data, ip, parent_ip, flags, preempt_count());
+	trace_function(tr, ip, parent_ip, flags, preempt_count());
 
 	per_cpu(tracing_cpu, cpu) = 1;
 
@@ -244,7 +244,7 @@ stop_critical_timing(unsigned long ip, unsigned long parent_ip)
 	atomic_inc(&data->disabled);
 
 	local_save_flags(flags);
-	trace_function(tr, data, ip, parent_ip, flags, preempt_count());
+	trace_function(tr, ip, parent_ip, flags, preempt_count());
 	check_critical_timing(tr, data, parent_ip ? : ip, cpu);
 	data->critical_start = 0;
 	atomic_dec(&data->disabled);
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index df175cb4564..c4f9add5ec9 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -43,7 +43,7 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
 	data = ctx_trace->data[cpu];
 
 	if (likely(!atomic_read(&data->disabled)))
-		tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
+		tracing_sched_switch_trace(ctx_trace, prev, next, flags, pc);
 
 	local_irq_restore(flags);
 }
@@ -66,7 +66,7 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
 	data = ctx_trace->data[cpu];
 
 	if (likely(!atomic_read(&data->disabled)))
-		tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
+		tracing_sched_wakeup_trace(ctx_trace, wakee, current,
 					   flags, pc);
 
 	local_irq_restore(flags);
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index a48c9b4b0c8..96d71648589 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -72,7 +72,7 @@ wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
 	if (task_cpu(wakeup_task) != cpu)
 		goto unlock;
 
-	trace_function(tr, data, ip, parent_ip, flags, pc);
+	trace_function(tr, ip, parent_ip, flags, pc);
 
  unlock:
 	__raw_spin_unlock(&wakeup_lock);
@@ -152,8 +152,8 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
 	if (unlikely(!tracer_enabled || next != wakeup_task))
 		goto out_unlock;
 
-	trace_function(wakeup_trace, data, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
-	tracing_sched_switch_trace(wakeup_trace, data, prev, next, flags, pc);
+	trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
+	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 
 	/*
 	 * usecs conversion is slow so we try to delay the conversion
@@ -254,10 +254,8 @@ probe_wakeup(struct rq *rq, struct task_struct *p, int success)
 
 	data = wakeup_trace->data[wakeup_cpu];
 	data->preempt_timestamp = ftrace_now(cpu);
-	tracing_sched_wakeup_trace(wakeup_trace, data, p, current,
-				   flags, pc);
-	trace_function(wakeup_trace, data, CALLER_ADDR1, CALLER_ADDR2,
-		       flags, pc);
+	tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
+	trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 
 out_locked:
 	__raw_spin_unlock(&wakeup_lock);
-- 
cgit v1.2.3-70-g09d2


From 73d8b8bc4f24a97a406d09c8268ac019f4ac661e Mon Sep 17 00:00:00 2001
From: Wenji Huang <wenji.huang@oracle.com>
Date: Tue, 17 Feb 2009 01:10:02 -0500
Subject: tracing: fix typing mistake in hint message and comments

Impact: cleanup

Fix incorrect hint message in code and typos in comments.

Signed-off-by: Wenji Huang <wenji.huang@oracle.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace_irqsoff.c      | 2 +-
 kernel/trace/trace_sched_switch.c | 2 +-
 kernel/trace/trace_sched_wakeup.c | 2 +-
 kernel/trace/trace_selftest.c     | 4 ++--
 kernel/trace/trace_stat.c         | 2 +-
 kernel/trace/trace_sysprof.c      | 2 +-
 6 files changed, 7 insertions(+), 7 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index c6b442d88de..9e5ebd84415 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -1,5 +1,5 @@
 /*
- * trace irqs off criticall timings
+ * trace irqs off critical timings
  *
  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 30e14fe8589..82fbb5a2df8 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -93,7 +93,7 @@ static int tracing_sched_register(void)
 	ret = register_trace_sched_switch(probe_sched_switch);
 	if (ret) {
 		pr_info("sched trace: Couldn't activate tracepoint"
-			" probe to kernel_sched_schedule\n");
+			" probe to kernel_sched_switch\n");
 		goto fail_deprobe_wake_new;
 	}
 
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 96d71648589..276c51aaf31 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -284,7 +284,7 @@ static void start_wakeup_tracer(struct trace_array *tr)
 	ret = register_trace_sched_switch(probe_wakeup_sched_switch);
 	if (ret) {
 		pr_info("sched trace: Couldn't activate tracepoint"
-			" probe to kernel_sched_schedule\n");
+			" probe to kernel_sched_switch\n");
 		goto fail_deprobe_wake_new;
 	}
 
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index c72e749bcbe..01415f4edaa 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -107,9 +107,9 @@ int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 	func();
 
 	/*
-	 * Some archs *cough*PowerPC*cough* add charachters to the
+	 * Some archs *cough*PowerPC*cough* add characters to the
 	 * start of the function names. We simply put a '*' to
-	 * accomodate them.
+	 * accommodate them.
 	 */
 	func_name = "*" STR(DYN_FTRACE_TEST_NAME);
 
diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index eae9cef3929..39310e3434e 100644
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -30,7 +30,7 @@ struct tracer_stat_session {
 	struct dentry		*file;
 };
 
-/* All of the sessions currently in use. Each stat file embeed one session */
+/* All of the sessions currently in use. Each stat file embed one session */
 static LIST_HEAD(all_stat_sessions);
 static DEFINE_MUTEX(all_stat_sessions_mutex);
 
diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index 7c9a2d82a7d..c771af4e8f1 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -327,5 +327,5 @@ void init_tracer_sysprof_debugfs(struct dentry *d_tracer)
 			d_tracer, NULL, &sysprof_sample_fops);
 	if (entry)
 		return;
-	pr_warning("Could not create debugfs 'dyn_ftrace_total_info' entry\n");
+	pr_warning("Could not create debugfs 'sysprof_sample_period' entry\n");
 }
-- 
cgit v1.2.3-70-g09d2


From 6eaaa5d57e76c454479833fc8594cd7c3b75c789 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Wed, 11 Feb 2009 02:25:00 +0100
Subject: tracing/core: use appropriate waiting on trace_pipe

Impact: api and pipe waiting change

Currently, the waiting used in tracing_read_pipe() is done through a
100 msecs schedule_timeout() loop which periodically check if there
are traces on the buffer.

This can cause small latencies for programs which are reading the incoming
events.

This patch makes the reader waiting for the trace_wait waitqueue except
for few tracers such as the sched and functions tracers which might be
already hold the runqueue lock while waking up the reader.

This is performed through a new callback wait_pipe() on struct tracer.
If none is implemented on a specific tracer, the default waiting for
trace_wait queue is attached.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace.c                 | 62 ++++++++++++++++++++++++------------
 kernel/trace/trace.h                 | 25 +++++++++++++--
 kernel/trace/trace_functions.c       |  1 +
 kernel/trace/trace_functions_graph.c |  1 +
 kernel/trace/trace_sched_switch.c    |  1 +
 kernel/trace/trace_sched_wakeup.c    |  1 +
 6 files changed, 67 insertions(+), 24 deletions(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dc61e82faad..881a94474d7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -499,6 +499,9 @@ __acquires(kernel_lock)
 	else
 		if (!type->flags->opts)
 			type->flags->opts = dummy_tracer_opt;
+	if (!type->wait_pipe)
+		type->wait_pipe = default_wait_pipe;
+
 
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 	if (type->selftest && !tracing_selftest_disabled) {
@@ -1064,7 +1067,10 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
 	entry->next_prio		= wakee->prio;
 	entry->next_state		= wakee->state;
 	entry->next_cpu			= task_cpu(wakee);
-	trace_buffer_unlock_commit(tr, event, flags, pc);
+
+	ring_buffer_unlock_commit(tr->buffer, event);
+	ftrace_trace_stack(tr, flags, 6, pc);
+	ftrace_trace_userstack(tr, flags, pc);
 }
 
 void
@@ -2392,6 +2398,38 @@ tracing_poll_pipe(struct file *filp, poll_table *poll_table)
 	}
 }
 
+
+void default_wait_pipe(struct trace_iterator *iter)
+{
+	DEFINE_WAIT(wait);
+
+	prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
+
+	if (trace_empty(iter))
+		schedule();
+
+	finish_wait(&trace_wait, &wait);
+}
+
+/*
+ * This is a make-shift waitqueue.
+ * A tracer might use this callback on some rare cases:
+ *
+ *  1) the current tracer might hold the runqueue lock when it wakes up
+ *     a reader, hence a deadlock (sched, function, and function graph tracers)
+ *  2) the function tracers, trace all functions, we don't want
+ *     the overhead of calling wake_up and friends
+ *     (and tracing them too)
+ *
+ *     Anyway, this is really very primitive wakeup.
+ */
+void poll_wait_pipe(struct trace_iterator *iter)
+{
+	set_current_state(TASK_INTERRUPTIBLE);
+	/* sleep for 100 msecs, and try again. */
+	schedule_timeout(HZ / 10);
+}
+
 /* Must be called with trace_types_lock mutex held. */
 static int tracing_wait_pipe(struct file *filp)
 {
@@ -2403,30 +2441,14 @@ static int tracing_wait_pipe(struct file *filp)
 			return -EAGAIN;
 		}
 
-		/*
-		 * This is a make-shift waitqueue. The reason we don't use
-		 * an actual wait queue is because:
-		 *  1) we only ever have one waiter
-		 *  2) the tracing, traces all functions, we don't want
-		 *     the overhead of calling wake_up and friends
-		 *     (and tracing them too)
-		 *     Anyway, this is really very primitive wakeup.
-		 */
-		set_current_state(TASK_INTERRUPTIBLE);
-		iter->tr->waiter = current;
-
 		mutex_unlock(&trace_types_lock);
 
-		/* sleep for 100 msecs, and try again. */
-		schedule_timeout(HZ/10);
+		iter->trace->wait_pipe(iter);
 
 		mutex_lock(&trace_types_lock);
 
-		iter->tr->waiter = NULL;
-
-		if (signal_pending(current)) {
+		if (signal_pending(current))
 			return -EINTR;
-		}
 
 		if (iter->trace != current_trace)
 			return 0;
@@ -2442,8 +2464,6 @@ static int tracing_wait_pipe(struct file *filp)
 		 */
 		if (!tracer_enabled && iter->pos)
 			break;
-
-		continue;
 	}
 
 	return 1;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index dbff0207b21..eed732c151f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -337,18 +337,34 @@ struct tracer_flags {
 #define TRACER_OPT(s, b)	.name = #s, .bit = b
 
 
-/*
- * A specific tracer, represented by methods that operate on a trace array:
+/**
+ * struct tracer - a specific tracer and its callbacks to interact with debugfs
+ * @name: the name chosen to select it on the available_tracers file
+ * @init: called when one switches to this tracer (echo name > current_tracer)
+ * @reset: called when one switches to another tracer
+ * @start: called when tracing is unpaused (echo 1 > tracing_enabled)
+ * @stop: called when tracing is paused (echo 0 > tracing_enabled)
+ * @open: called when the trace file is opened
+ * @pipe_open: called when the trace_pipe file is opened
+ * @wait_pipe: override how the user waits for traces on trace_pipe
+ * @close: called when the trace file is released
+ * @read: override the default read callback on trace_pipe
+ * @splice_read: override the default splice_read callback on trace_pipe
+ * @selftest: selftest to run on boot (see trace_selftest.c)
+ * @print_headers: override the first lines that describe your columns
+ * @print_line: callback that prints a trace
+ * @set_flag: signals one of your private flags changed (trace_options file)
+ * @flags: your private flags
  */
 struct tracer {
 	const char		*name;
-	/* Your tracer should raise a warning if init fails */
 	int			(*init)(struct trace_array *tr);
 	void			(*reset)(struct trace_array *tr);
 	void			(*start)(struct trace_array *tr);
 	void			(*stop)(struct trace_array *tr);
 	void			(*open)(struct trace_iterator *iter);
 	void			(*pipe_open)(struct trace_iterator *iter);
+	void			(*wait_pipe)(struct trace_iterator *iter);
 	void			(*close)(struct trace_iterator *iter);
 	ssize_t			(*read)(struct trace_iterator *iter,
 					struct file *filp, char __user *ubuf,
@@ -432,6 +448,9 @@ void tracing_generic_entry_update(struct trace_entry *entry,
 				  unsigned long flags,
 				  int pc);
 
+void default_wait_pipe(struct trace_iterator *iter);
+void poll_wait_pipe(struct trace_iterator *iter);
+
 void ftrace(struct trace_array *tr,
 			    struct trace_array_cpu *data,
 			    unsigned long ip,
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 4c113a8c466..c9a0b7df44f 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -225,6 +225,7 @@ static struct tracer function_trace __read_mostly =
 	.init		= function_trace_init,
 	.reset		= function_trace_reset,
 	.start		= function_trace_start,
+	.wait_pipe	= poll_wait_pipe,
 	.flags		= &func_flags,
 	.set_flag	= func_set_flag,
 #ifdef CONFIG_FTRACE_SELFTEST
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 519a0cab153..0ff5cb66190 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -757,6 +757,7 @@ static struct tracer graph_trace __read_mostly = {
 	.name	     	= "function_graph",
 	.open		= graph_trace_open,
 	.close		= graph_trace_close,
+	.wait_pipe	= poll_wait_pipe,
 	.init	     	= graph_trace_init,
 	.reset	     	= graph_trace_reset,
 	.print_line	= print_graph_function,
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 82fbb5a2df8..77132c2cf3d 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -221,6 +221,7 @@ static struct tracer sched_switch_trace __read_mostly =
 	.reset		= sched_switch_trace_reset,
 	.start		= sched_switch_trace_start,
 	.stop		= sched_switch_trace_stop,
+	.wait_pipe	= poll_wait_pipe,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_sched_switch,
 #endif
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 276c51aaf31..db55f7aaa64 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -380,6 +380,7 @@ static struct tracer wakeup_rt_tracer __read_mostly =
 	.reset		= wakeup_tracer_reset,
 	.start		= wakeup_tracer_start,
 	.stop		= wakeup_tracer_stop,
+	.wait_pipe	= poll_wait_pipe,
 	.print_max	= 1,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_wakeup,
-- 
cgit v1.2.3-70-g09d2


From e9d25fe6eaa2c720bb3ea661b660e58d54fa38bf Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Wed, 4 Mar 2009 22:15:30 -0500
Subject: tracing: have latency tracers set the latency format

The latency tracers (irqsoff, preemptoff, preemptirqsoff, and wakeup)
are pretty useless with the default output format. This patch makes them
automatically enable the latency format when they are selected. They
also record the state of the latency option, and if it was not enabled
when selected, they disable it on reset.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
 kernel/trace/trace_irqsoff.c      | 8 ++++++++
 kernel/trace/trace_sched_wakeup.c | 8 ++++++++
 2 files changed, 16 insertions(+)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 9e5ebd84415..b923d13e2fa 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -32,6 +32,8 @@ enum {
 
 static int trace_type __read_mostly;
 
+static int save_lat_flag;
+
 #ifdef CONFIG_PREEMPT_TRACER
 static inline int
 preempt_trace(void)
@@ -370,6 +372,9 @@ static void stop_irqsoff_tracer(struct trace_array *tr)
 
 static void __irqsoff_tracer_init(struct trace_array *tr)
 {
+	save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
+	trace_flags |= TRACE_ITER_LATENCY_FMT;
+
 	tracing_max_latency = 0;
 	irqsoff_trace = tr;
 	/* make sure that the tracer is visible */
@@ -380,6 +385,9 @@ static void __irqsoff_tracer_init(struct trace_array *tr)
 static void irqsoff_tracer_reset(struct trace_array *tr)
 {
 	stop_irqsoff_tracer(tr);
+
+	if (!save_lat_flag)
+		trace_flags &= ~TRACE_ITER_LATENCY_FMT;
 }
 
 static void irqsoff_tracer_start(struct trace_array *tr)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index db55f7aaa64..3c5ad6b2ec8 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -32,6 +32,8 @@ static raw_spinlock_t wakeup_lock =
 
 static void __wakeup_reset(struct trace_array *tr);
 
+static int save_lat_flag;
+
 #ifdef CONFIG_FUNCTION_TRACER
 /*
  * irqsoff uses its own tracer function to keep the overhead down:
@@ -324,6 +326,9 @@ static void stop_wakeup_tracer(struct trace_array *tr)
 
 static int __wakeup_tracer_init(struct trace_array *tr)
 {
+	save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
+	trace_flags |= TRACE_ITER_LATENCY_FMT;
+
 	tracing_max_latency = 0;
 	wakeup_trace = tr;
 	start_wakeup_tracer(tr);
@@ -347,6 +352,9 @@ static void wakeup_tracer_reset(struct trace_array *tr)
 	stop_wakeup_tracer(tr);
 	/* make sure we put back any tasks we are tracing */
 	wakeup_reset(tr);
+
+	if (!save_lat_flag)
+		trace_flags &= ~TRACE_ITER_LATENCY_FMT;
 }
 
 static void wakeup_tracer_start(struct trace_array *tr)
-- 
cgit v1.2.3-70-g09d2


From 301fd748e2c81e78e74edbc694a64caa7b95dda2 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Fri, 3 Apr 2009 11:12:23 -0400
Subject: tracing: remove CALLER_ADDR2 from wakeup tracer

Maneesh Soni was getting a crash when running the wakeup tracer.
We debugged it down to the recording of the function with the
CALLER_ADDR2 macro.  This is used to get the location of the caller
to schedule.

But the problem comes when schedule is called by assmebly. In the case
that Maneesh had, retint_careful would call schedule. But retint_careful
does not set up a proper frame pointer. CALLER_ADDR2 is defined as
__builtin_return_address(2). This produces the following assembly in
the wakeup tracer code.

   mov    0x0(%rbp),%rcx  <--- get the frame pointer of the caller
   mov    %r14d,%r8d
   mov    0xf2de8e(%rip),%rdi

   mov    0x8(%rcx),%rsi  <-- this is __builtin_return_address(1)
   mov    0x28(%rdi,%rax,8),%rbx

   mov    (%rcx),%rax  <-- get the frame pointer of the caller's caller
   mov    %r12,%rcx
   mov    0x8(%rax),%rdx <-- this is __builtin_return_address(2)

At the reading of 0x8(%rax) Maneesh's machine would take a fault.
The reason is that retint_careful did not set up the return address
and the content of %rax here was zero.

To verify this, I sent Maneesh a patch to create a frame pointer
in retint_careful. He ran the test again but this time he would take
the same type of fault from sysret_careful. The retint_careful was no
longer an issue, but there are other callers that still have issues.

Instead of adding frame pointers for all callers to schedule (in possibly
all archs), it is much safer to simply not use CALLER_ADDR2. This
loses out on knowing what called schedule, but the function tracer
will help there if needed.

Reported-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/trace/trace_sched_wakeup.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'kernel/trace/trace_sched_wakeup.c')

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 3c5ad6b2ec8..5bc00e8f153 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -154,7 +154,7 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
 	if (unlikely(!tracer_enabled || next != wakeup_task))
 		goto out_unlock;
 
-	trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
+	trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
 	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 
 	/*
@@ -257,6 +257,12 @@ probe_wakeup(struct rq *rq, struct task_struct *p, int success)
 	data = wakeup_trace->data[wakeup_cpu];
 	data->preempt_timestamp = ftrace_now(cpu);
 	tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
+
+	/*
+	 * We must be careful in using CALLER_ADDR2. But since wake_up
+	 * is not called by an assembly function  (where as schedule is)
+	 * it should be safe to use it here.
+	 */
 	trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
 
 out_locked:
-- 
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