[PATCH 00/19] [GIT PULL][3.8] tracing: updates (v2)

[PATCH 00/19] [GIT PULL][3.8] tracing: updates (v2)

[Steven Rostedt]

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Ingo,

I removed the few problem patches (and their dependencies) and
retested the result.

Please pull the latest tip/perf/core-2 tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/perf/core-2

Head SHA1: 7bcfaf54f591a0775254c4ea679faf615152ee3a


Daniel Walter (1):
      tracing: Replace strict_strto* with kstrto*

David Sharp (2):
      tracing: Trivial cleanup
      tracing: Reset ring buffer when changing trace_clocks

Hiraku Toyooka (1):
      tracing: Change tracer's integer flags to bool

Michal Hocko (1):
      linux/kernel.h: Remove duplicate trace_printk declaration

Slava Pestov (1):
      ring-buffer: Add a 'dropped events' counter

Steven Rostedt (11):
      tracing: Allow tracers to start at core initcall
      tracing: Expand ring buffer when trace_printk() is used
      tracing: Enable comm recording if trace_printk() is used
      tracing: Have tracing_sched_wakeup_trace() use standard unlock_commit
      tracing: Cache comms only after an event occurred
      tracing: Separate open function from set_event and available_events
      tracing: Remove unused function unregister_tracer()
      tracing: Make tracing_enabled be equal to tracing_on
      tracing: Remove deprecated tracing_enabled file
      tracing: Use irq_work for wake ups and remove *_nowake_*() functions
      tracing: Add trace_options kernel command line parameter

Vaibhav Nagarnaik (1):
      tracing: Cleanup unnecessary function declarations

Yoshihiro YUNOMAE (1):
      ring-buffer: Change unsigned long type of ring_buffer_oldest_event_ts() to u64

----
 Documentation/kernel-parameters.txt  |   16 ++
 include/linux/ftrace_event.h         |   14 +-
 include/linux/kernel.h               |    7 +-
 include/linux/ring_buffer.h          |    3 +-
 include/trace/ftrace.h               |    3 +-
 include/trace/syscall.h              |   23 ---
 kernel/trace/Kconfig                 |    1 +
 kernel/trace/ftrace.c                |    6 +-
 kernel/trace/ring_buffer.c           |   51 ++++-
 kernel/trace/trace.c                 |  372 +++++++++++++++++-----------------
 kernel/trace/trace.h                 |   14 +-
 kernel/trace/trace_branch.c          |    4 +-
 kernel/trace/trace_events.c          |   51 +++--
 kernel/trace/trace_events_filter.c   |    4 +-
 kernel/trace/trace_functions.c       |    5 +-
 kernel/trace/trace_functions_graph.c |    6 +-
 kernel/trace/trace_irqsoff.c         |   14 +-
 kernel/trace/trace_kprobe.c          |   10 +-
 kernel/trace/trace_probe.c           |   14 +-
 kernel/trace/trace_sched_switch.c    |    4 +-
 kernel/trace/trace_sched_wakeup.c    |   10 +-
 kernel/trace/trace_selftest.c        |   13 +-
 kernel/trace/trace_syscalls.c        |   61 +++---
 kernel/trace/trace_uprobe.c          |    2 +-
 24 files changed, 365 insertions(+), 343 deletions(-)

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[PATCH 01/19] tracing: Replace strict_strto* with kstrto*

[Steven Rostedt]

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From: Daniel Walter <sahne@0x90.at>

 * remove old string conversions with kstrto*

Link: http://lkml.kernel.org/r/20120926200838.GC1244@0x90.at

Signed-off-by: Daniel Walter <sahne@0x90.at>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c              |    2 +-
 kernel/trace/trace.c               |    2 +-
 kernel/trace/trace_events_filter.c |    4 ++--
 kernel/trace/trace_functions.c     |    2 +-
 kernel/trace/trace_kprobe.c        |    2 +-
 kernel/trace/trace_probe.c         |   14 +++++++-------
 kernel/trace/trace_uprobe.c        |    2 +-
 7 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9dcf15d..60ad606 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4381,7 +4381,7 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf,
 	if (strlen(tmp) == 0)
 		return 1;
 
-	ret = strict_strtol(tmp, 10, &val);
+	ret = kstrtol(tmp, 10, &val);
 	if (ret < 0)
 		return ret;
 
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 31e4f55..f6928ed 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -431,7 +431,7 @@ static int __init set_tracing_thresh(char *str)
 
 	if (!str)
 		return 0;
-	ret = strict_strtoul(str, 0, &threshold);
+	ret = kstrtoul(str, 0, &threshold);
 	if (ret < 0)
 		return 0;
 	tracing_thresh = threshold * 1000;
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index c154797..e5b0ca8 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1000,9 +1000,9 @@ static int init_pred(struct filter_parse_state *ps,
 		}
 	} else {
 		if (field->is_signed)
-			ret = strict_strtoll(pred->regex.pattern, 0, &val);
+			ret = kstrtoll(pred->regex.pattern, 0, &val);
 		else
-			ret = strict_strtoull(pred->regex.pattern, 0, &val);
+			ret = kstrtoull(pred->regex.pattern, 0, &val);
 		if (ret) {
 			parse_error(ps, FILT_ERR_ILLEGAL_INTVAL, 0);
 			return -EINVAL;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 507a7a9..618dcf8 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -366,7 +366,7 @@ ftrace_trace_onoff_callback(struct ftrace_hash *hash,
 	 * We use the callback data field (which is a pointer)
 	 * as our counter.
 	 */
-	ret = strict_strtoul(number, 0, (unsigned long *)&count);
+	ret = kstrtoul(number, 0, (unsigned long *)&count);
 	if (ret)
 		return ret;
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1a21170..5a3c533 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -444,7 +444,7 @@ static int create_trace_probe(int argc, char **argv)
 			return -EINVAL;
 		}
 		/* an address specified */
-		ret = strict_strtoul(&argv[1][0], 0, (unsigned long *)&addr);
+		ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
 		if (ret) {
 			pr_info("Failed to parse address.\n");
 			return ret;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index daa9980..412e959 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -441,7 +441,7 @@ static const struct fetch_type *find_fetch_type(const char *type)
 			goto fail;
 
 		type++;
-		if (strict_strtoul(type, 0, &bs))
+		if (kstrtoul(type, 0, &bs))
 			goto fail;
 
 		switch (bs) {
@@ -501,8 +501,8 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
 
 	tmp = strchr(symbol, '+');
 	if (tmp) {
-		/* skip sign because strict_strtol doesn't accept '+' */
-		ret = strict_strtoul(tmp + 1, 0, offset);
+		/* skip sign because kstrtoul doesn't accept '+' */
+		ret = kstrtoul(tmp + 1, 0, offset);
 		if (ret)
 			return ret;
 
@@ -533,7 +533,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 			else
 				ret = -EINVAL;
 		} else if (isdigit(arg[5])) {
-			ret = strict_strtoul(arg + 5, 10, &param);
+			ret = kstrtoul(arg + 5, 10, &param);
 			if (ret || param > PARAM_MAX_STACK)
 				ret = -EINVAL;
 			else {
@@ -579,7 +579,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 
 	case '@':	/* memory or symbol */
 		if (isdigit(arg[1])) {
-			ret = strict_strtoul(arg + 1, 0, &param);
+			ret = kstrtoul(arg + 1, 0, &param);
 			if (ret)
 				break;
 
@@ -597,14 +597,14 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
 		break;
 
 	case '+':	/* deref memory */
-		arg++;	/* Skip '+', because strict_strtol() rejects it. */
+		arg++;	/* Skip '+', because kstrtol() rejects it. */
 	case '-':
 		tmp = strchr(arg, '(');
 		if (!tmp)
 			break;
 
 		*tmp = '\0';
-		ret = strict_strtol(arg, 0, &offset);
+		ret = kstrtol(arg, 0, &offset);
 
 		if (ret)
 			break;
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 03003cd..4ff9ca4 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -252,7 +252,7 @@ static int create_trace_uprobe(int argc, char **argv)
 	if (ret)
 		goto fail_address_parse;
 
-	ret = strict_strtoul(arg, 0, &offset);
+	ret = kstrtoul(arg, 0, &offset);
 	if (ret)
 		goto fail_address_parse;
 
-- 
1.7.10.4



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[PATCH 02/19] tracing: Allow tracers to start at core initcall

[Steven Rostedt]

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From: Steven Rostedt <srostedt@redhat.com>

There's times during debugging that it is helpful to see traces of early
boot functions. But the tracers are initialized at device_initcall()
which is quite late during the boot process. Setting the kernel command
line parameter ftrace=function will not show anything until the function
tracer is initialized. This prevents being able to trace functions before
device_initcall().

There's no reason that the tracers need to be initialized so late in the
boot process. Move them up to core_initcall() as they still need to come
after early_initcall() which initializes the tracing buffers.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c                |    4 ++--
 kernel/trace/trace_branch.c          |    2 +-
 kernel/trace/trace_functions.c       |    3 +--
 kernel/trace/trace_functions_graph.c |    2 +-
 kernel/trace/trace_irqsoff.c         |    2 +-
 kernel/trace/trace_sched_wakeup.c    |    2 +-
 6 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 60ad606..4451aa3 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2868,7 +2868,7 @@ static int __init ftrace_mod_cmd_init(void)
 {
 	return register_ftrace_command(&ftrace_mod_cmd);
 }
-device_initcall(ftrace_mod_cmd_init);
+core_initcall(ftrace_mod_cmd_init);
 
 static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
 				      struct ftrace_ops *op, struct pt_regs *pt_regs)
@@ -4055,7 +4055,7 @@ static int __init ftrace_nodyn_init(void)
 	ftrace_enabled = 1;
 	return 0;
 }
-device_initcall(ftrace_nodyn_init);
+core_initcall(ftrace_nodyn_init);
 
 static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
 static inline void ftrace_startup_enable(int command) { }
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index 8d3538b..bd3e0ee 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -199,7 +199,7 @@ __init static int init_branch_tracer(void)
 	}
 	return register_tracer(&branch_trace);
 }
-device_initcall(init_branch_tracer);
+core_initcall(init_branch_tracer);
 
 #else
 static inline
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 618dcf8..bb227e3 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -411,5 +411,4 @@ static __init int init_function_trace(void)
 	init_func_cmd_traceon();
 	return register_tracer(&function_trace);
 }
-device_initcall(init_function_trace);
-
+core_initcall(init_function_trace);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 99b4378..a84b558 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1474,4 +1474,4 @@ static __init int init_graph_trace(void)
 	return register_tracer(&graph_trace);
 }
 
-device_initcall(init_graph_trace);
+core_initcall(init_graph_trace);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index d98ee82..11edebd 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -698,4 +698,4 @@ __init static int init_irqsoff_tracer(void)
 
 	return 0;
 }
-device_initcall(init_irqsoff_tracer);
+core_initcall(init_irqsoff_tracer);
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 02170c0..2f6af78 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -637,4 +637,4 @@ __init static int init_wakeup_tracer(void)
 
 	return 0;
 }
-device_initcall(init_wakeup_tracer);
+core_initcall(init_wakeup_tracer);
-- 
1.7.10.4



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[PATCH 03/19] tracing: Change tracers integer flags to bool

[Steven Rostedt]

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From: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>

print_max and use_max_tr in struct tracer are "int" variables and
used like flags. This is wasteful, so change the type to "bool".

Link: http://lkml.kernel.org/r/20121002082710.9807.86393.stgit@falsita

Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.h              |    4 ++--
 kernel/trace/trace_irqsoff.c      |   12 ++++++------
 kernel/trace/trace_sched_wakeup.c |    8 ++++----
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c15f528..c56a233 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -285,8 +285,8 @@ struct tracer {
 	int			(*set_flag)(u32 old_flags, u32 bit, int set);
 	struct tracer		*next;
 	struct tracer_flags	*flags;
-	int			print_max;
-	int			use_max_tr;
+	bool			print_max;
+	bool			use_max_tr;
 };
 
 
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 11edebd..5ffce7b 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -604,7 +604,7 @@ static struct tracer irqsoff_tracer __read_mostly =
 	.reset		= irqsoff_tracer_reset,
 	.start		= irqsoff_tracer_start,
 	.stop		= irqsoff_tracer_stop,
-	.print_max	= 1,
+	.print_max	= true,
 	.print_header   = irqsoff_print_header,
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
@@ -614,7 +614,7 @@ static struct tracer irqsoff_tracer __read_mostly =
 #endif
 	.open           = irqsoff_trace_open,
 	.close          = irqsoff_trace_close,
-	.use_max_tr	= 1,
+	.use_max_tr	= true,
 };
 # define register_irqsoff(trace) register_tracer(&trace)
 #else
@@ -637,7 +637,7 @@ static struct tracer preemptoff_tracer __read_mostly =
 	.reset		= irqsoff_tracer_reset,
 	.start		= irqsoff_tracer_start,
 	.stop		= irqsoff_tracer_stop,
-	.print_max	= 1,
+	.print_max	= true,
 	.print_header   = irqsoff_print_header,
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
@@ -647,7 +647,7 @@ static struct tracer preemptoff_tracer __read_mostly =
 #endif
 	.open		= irqsoff_trace_open,
 	.close		= irqsoff_trace_close,
-	.use_max_tr	= 1,
+	.use_max_tr	= true,
 };
 # define register_preemptoff(trace) register_tracer(&trace)
 #else
@@ -672,7 +672,7 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
 	.reset		= irqsoff_tracer_reset,
 	.start		= irqsoff_tracer_start,
 	.stop		= irqsoff_tracer_stop,
-	.print_max	= 1,
+	.print_max	= true,
 	.print_header   = irqsoff_print_header,
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
@@ -682,7 +682,7 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
 #endif
 	.open		= irqsoff_trace_open,
 	.close		= irqsoff_trace_close,
-	.use_max_tr	= 1,
+	.use_max_tr	= true,
 };
 
 # define register_preemptirqsoff(trace) register_tracer(&trace)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 2f6af78..bc64fc1 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -589,7 +589,7 @@ static struct tracer wakeup_tracer __read_mostly =
 	.reset		= wakeup_tracer_reset,
 	.start		= wakeup_tracer_start,
 	.stop		= wakeup_tracer_stop,
-	.print_max	= 1,
+	.print_max	= true,
 	.print_header	= wakeup_print_header,
 	.print_line	= wakeup_print_line,
 	.flags		= &tracer_flags,
@@ -599,7 +599,7 @@ static struct tracer wakeup_tracer __read_mostly =
 #endif
 	.open		= wakeup_trace_open,
 	.close		= wakeup_trace_close,
-	.use_max_tr	= 1,
+	.use_max_tr	= true,
 };
 
 static struct tracer wakeup_rt_tracer __read_mostly =
@@ -610,7 +610,7 @@ static struct tracer wakeup_rt_tracer __read_mostly =
 	.start		= wakeup_tracer_start,
 	.stop		= wakeup_tracer_stop,
 	.wait_pipe	= poll_wait_pipe,
-	.print_max	= 1,
+	.print_max	= true,
 	.print_header	= wakeup_print_header,
 	.print_line	= wakeup_print_line,
 	.flags		= &tracer_flags,
@@ -620,7 +620,7 @@ static struct tracer wakeup_rt_tracer __read_mostly =
 #endif
 	.open		= wakeup_trace_open,
 	.close		= wakeup_trace_close,
-	.use_max_tr	= 1,
+	.use_max_tr	= true,
 };
 
 __init static int init_wakeup_tracer(void)
-- 
1.7.10.4



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[PATCH 04/19] ring-buffer: Add a dropped events counter

[Steven Rostedt]

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From: Slava Pestov <slavapestov@google.com>

The existing 'overrun' counter is incremented when the ring
buffer wraps around, with overflow on (the default). We wanted
a way to count requests lost from the buffer filling up with
overflow off, too. I decided to add a new counter instead
of retro-fitting the existing one because it seems like a
different statistic to count conceptually, and also because
of how the code was structured.

Link: http://lkml.kernel.org/r/1310765038-26399-1-git-send-email-slavapestov@google.com

Signed-off-by: Slava Pestov <slavapestov@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ring_buffer.h |    1 +
 kernel/trace/ring_buffer.c  |   41 +++++++++++++++++++++++++++++++++++------
 kernel/trace/trace.c        |    3 +++
 3 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index 6c8835f..2007375 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -166,6 +166,7 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
+unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
 
 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b979426..0ebeb1d 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -460,9 +460,10 @@ struct ring_buffer_per_cpu {
 	unsigned long			lost_events;
 	unsigned long			last_overrun;
 	local_t				entries_bytes;
-	local_t				commit_overrun;
-	local_t				overrun;
 	local_t				entries;
+	local_t				overrun;
+	local_t				commit_overrun;
+	local_t				dropped_events;
 	local_t				committing;
 	local_t				commits;
 	unsigned long			read;
@@ -2155,8 +2156,10 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
 			 * If we are not in overwrite mode,
 			 * this is easy, just stop here.
 			 */
-			if (!(buffer->flags & RB_FL_OVERWRITE))
+			if (!(buffer->flags & RB_FL_OVERWRITE)) {
+				local_inc(&cpu_buffer->dropped_events);
 				goto out_reset;
+			}
 
 			ret = rb_handle_head_page(cpu_buffer,
 						  tail_page,
@@ -2995,7 +2998,8 @@ unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu)
 EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu);
 
 /**
- * ring_buffer_overrun_cpu - get the number of overruns in a cpu_buffer
+ * ring_buffer_overrun_cpu - get the number of overruns caused by the ring
+ * buffer wrapping around (only if RB_FL_OVERWRITE is on).
  * @buffer: The ring buffer
  * @cpu: The per CPU buffer to get the number of overruns from
  */
@@ -3015,7 +3019,9 @@ unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu)
 EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu);
 
 /**
- * ring_buffer_commit_overrun_cpu - get the number of overruns caused by commits
+ * ring_buffer_commit_overrun_cpu - get the number of overruns caused by
+ * commits failing due to the buffer wrapping around while there are uncommitted
+ * events, such as during an interrupt storm.
  * @buffer: The ring buffer
  * @cpu: The per CPU buffer to get the number of overruns from
  */
@@ -3036,6 +3042,28 @@ ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu)
 EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu);
 
 /**
+ * ring_buffer_dropped_events_cpu - get the number of dropped events caused by
+ * the ring buffer filling up (only if RB_FL_OVERWRITE is off).
+ * @buffer: The ring buffer
+ * @cpu: The per CPU buffer to get the number of overruns from
+ */
+unsigned long
+ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu)
+{
+	struct ring_buffer_per_cpu *cpu_buffer;
+	unsigned long ret;
+
+	if (!cpumask_test_cpu(cpu, buffer->cpumask))
+		return 0;
+
+	cpu_buffer = buffer->buffers[cpu];
+	ret = local_read(&cpu_buffer->dropped_events);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ring_buffer_dropped_events_cpu);
+
+/**
  * ring_buffer_entries - get the number of entries in a buffer
  * @buffer: The ring buffer
  *
@@ -3864,9 +3892,10 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer)
 	local_set(&cpu_buffer->reader_page->page->commit, 0);
 	cpu_buffer->reader_page->read = 0;
 
-	local_set(&cpu_buffer->commit_overrun, 0);
 	local_set(&cpu_buffer->entries_bytes, 0);
 	local_set(&cpu_buffer->overrun, 0);
+	local_set(&cpu_buffer->commit_overrun, 0);
+	local_set(&cpu_buffer->dropped_events, 0);
 	local_set(&cpu_buffer->entries, 0);
 	local_set(&cpu_buffer->committing, 0);
 	local_set(&cpu_buffer->commits, 0);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f6928ed..36c213f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4385,6 +4385,9 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 	usec_rem = do_div(t, USEC_PER_SEC);
 	trace_seq_printf(s, "now ts: %5llu.%06lu\n", t, usec_rem);
 
+	cnt = ring_buffer_dropped_events_cpu(tr->buffer, cpu);
+	trace_seq_printf(s, "dropped events: %ld\n", cnt);
+
 	count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
 
 	kfree(s);
-- 
1.7.10.4



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[PATCH 05/19] tracing: Expand ring buffer when trace_printk() is used

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 1673 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Since tracing is not used by 99% of Linux users, even though tracing
may be configured in, it does not make sense to allocate 1.4 Megs
per CPU for the ring buffers if they are not used. Thus, on boot up
the ring buffers are set to a minimal size until something needs the
and they are expanded.

This works well for events and tracers (function, etc), but for the
asynchronous use of trace_printk() which can write to the ring buffer
at any time, does not expand the buffers.

On boot up a check is made to see if any trace_printk() is used to
see if the trace_printk() temp buffer pages should be allocated. This
same code can be used to expand the buffers as well.

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 36c213f..a5411b7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1571,6 +1571,9 @@ void trace_printk_init_buffers(void)
 
 	pr_info("ftrace: Allocated trace_printk buffers\n");
 
+	/* Expand the buffers to set size */
+	tracing_update_buffers();
+
 	buffers_allocated = 1;
 }
 
@@ -3030,6 +3033,10 @@ static int __tracing_resize_ring_buffer(unsigned long size, int cpu)
 	 */
 	ring_buffer_expanded = 1;
 
+	/* May be called before buffers are initialized */
+	if (!global_trace.buffer)
+		return 0;
+
 	ret = ring_buffer_resize(global_trace.buffer, size, cpu);
 	if (ret < 0)
 		return ret;
-- 
1.7.10.4



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[PATCH 06/19] tracing: Enable comm recording if trace_printk() is used

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 3831 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

If comm recording is not enabled when trace_printk() is used then
you just get this type of output:

[ adding trace_printk("hello! %d", irq); in do_IRQ ]

           <...>-2843  [001] d.h.    80.812300: do_IRQ: hello! 14
           <...>-2734  [002] d.h2    80.824664: do_IRQ: hello! 14
           <...>-2713  [003] d.h.    80.829971: do_IRQ: hello! 14
           <...>-2814  [000] d.h.    80.833026: do_IRQ: hello! 14

By enabling the comm recorder when trace_printk is enabled:

       hackbench-6715  [001] d.h.   193.233776: do_IRQ: hello! 21
            sshd-2659  [001] d.h.   193.665862: do_IRQ: hello! 21
          <idle>-0     [001] d.h1   193.665996: do_IRQ: hello! 21

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c        |   36 ++++++++++++++++++++++++++++++++++--
 kernel/trace/trace.h        |    1 +
 kernel/trace/trace_events.c |    3 +++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a5411b7..b90a827 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1559,10 +1559,10 @@ static int alloc_percpu_trace_buffer(void)
 	return -ENOMEM;
 }
 
+static int buffers_allocated;
+
 void trace_printk_init_buffers(void)
 {
-	static int buffers_allocated;
-
 	if (buffers_allocated)
 		return;
 
@@ -1575,6 +1575,34 @@ void trace_printk_init_buffers(void)
 	tracing_update_buffers();
 
 	buffers_allocated = 1;
+
+	/*
+	 * trace_printk_init_buffers() can be called by modules.
+	 * If that happens, then we need to start cmdline recording
+	 * directly here. If the global_trace.buffer is already
+	 * allocated here, then this was called by module code.
+	 */
+	if (global_trace.buffer)
+		tracing_start_cmdline_record();
+}
+
+void trace_printk_start_comm(void)
+{
+	/* Start tracing comms if trace printk is set */
+	if (!buffers_allocated)
+		return;
+	tracing_start_cmdline_record();
+}
+
+static void trace_printk_start_stop_comm(int enabled)
+{
+	if (!buffers_allocated)
+		return;
+
+	if (enabled)
+		tracing_start_cmdline_record();
+	else
+		tracing_stop_cmdline_record();
 }
 
 /**
@@ -2797,6 +2825,9 @@ static void set_tracer_flags(unsigned int mask, int enabled)
 
 	if (mask == TRACE_ITER_OVERWRITE)
 		ring_buffer_change_overwrite(global_trace.buffer, enabled);
+
+	if (mask == TRACE_ITER_PRINTK)
+		trace_printk_start_stop_comm(enabled);
 }
 
 static ssize_t
@@ -5099,6 +5130,7 @@ __init static int tracer_alloc_buffers(void)
 
 	/* Only allocate trace_printk buffers if a trace_printk exists */
 	if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
+		/* Must be called before global_trace.buffer is allocated */
 		trace_printk_init_buffers();
 
 	/* To save memory, keep the ring buffer size to its minimum */
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c56a233..7824a55 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -841,6 +841,7 @@ extern const char *__start___trace_bprintk_fmt[];
 extern const char *__stop___trace_bprintk_fmt[];
 
 void trace_printk_init_buffers(void);
+void trace_printk_start_comm(void);
 
 #undef FTRACE_ENTRY
 #define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter)	\
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index d608d09..dec47e7 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1489,6 +1489,9 @@ static __init int event_trace_enable(void)
 		if (ret)
 			pr_warn("Failed to enable trace event: %s\n", token);
 	}
+
+	trace_printk_start_comm();
+
 	return 0;
 }
 
-- 
1.7.10.4



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[PATCH 07/19] tracing: Have tracing_sched_wakeup_trace() use standard unlock_commit

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 979 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The functon tracing_sched_wakeup_trace() does an open coded unlock
commit and save stack. This is what the trace_nowake_buffer_unlock_commit()
is for.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_sched_switch.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 7e62c0a..b0a136a 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -102,9 +102,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
 	entry->next_cpu			= task_cpu(wakee);
 
 	if (!filter_check_discard(call, entry, buffer, event))
-		ring_buffer_unlock_commit(buffer, event);
-	ftrace_trace_stack(tr->buffer, flags, 6, pc);
-	ftrace_trace_userstack(tr->buffer, flags, pc);
+		trace_nowake_buffer_unlock_commit(buffer, event, flags, pc);
 }
 
 static void
-- 
1.7.10.4



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[PATCH 08/19] tracing: Cache comms only after an event occurred

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 9974 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Whenever an event is registered, the comm of tasks are saved at
every task switch instead of saving them at every event. But if
an event isn't executed much, the comm cache will be filled up
by tasks that did not record the event and you lose out on the comms
that did.

Here's an example, if you enable the following events:

echo 1 > /debug/tracing/events/kvm/kvm_cr/enable
echo 1 > /debug/tracing/events/net/net_dev_xmit/enable

Note, there's no kvm running on this machine so the first event will
never be triggered, but because it is enabled, the storing of comms
will continue. If we now disable the network event:

echo 0 > /debug/tracing/events/net/net_dev_xmit/enable

and look at the trace:

cat /debug/tracing/trace
            sshd-2672  [001] ..s2   375.731616: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s1   375.731617: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s2   375.859356: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s1   375.859357: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s2   375.947351: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s1   375.947352: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s2   376.035383: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s1   376.035383: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
            sshd-2672  [001] ..s2   377.563806: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=226 rc=0
            sshd-2672  [001] ..s1   377.563807: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=226 rc=0
            sshd-2672  [001] ..s2   377.563834: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6be0 len=114 rc=0
            sshd-2672  [001] ..s1   377.563842: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6be0 len=114 rc=0

We see that process 2672 which triggered the events has the comm "sshd".
But if we run hackbench for a bit and look again:

cat /debug/tracing/trace
           <...>-2672  [001] ..s2   375.731616: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s1   375.731617: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s2   375.859356: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s1   375.859357: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s2   375.947351: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s1   375.947352: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s2   376.035383: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s1   376.035383: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0
           <...>-2672  [001] ..s2   377.563806: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=226 rc=0
           <...>-2672  [001] ..s1   377.563807: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=226 rc=0
           <...>-2672  [001] ..s2   377.563834: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6be0 len=114 rc=0
           <...>-2672  [001] ..s1   377.563842: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6be0 len=114 rc=0

The stored "sshd" comm has been flushed out and we get a useless "<...>".

But by only storing comms after a trace event occurred, we can run
hackbench all day and still get the same output.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c                 |   35 ++++++++++++++++++++++++++--------
 kernel/trace/trace.h                 |    3 +++
 kernel/trace/trace_branch.c          |    2 +-
 kernel/trace/trace_functions_graph.c |    4 ++--
 4 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b90a827..88111b0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -78,6 +78,13 @@ static int dummy_set_flag(u32 old_flags, u32 bit, int set)
 }
 
 /*
+ * To prevent the comm cache from being overwritten when no
+ * tracing is active, only save the comm when a trace event
+ * occurred.
+ */
+static DEFINE_PER_CPU(bool, trace_cmdline_save);
+
+/*
  * Kill all tracing for good (never come back).
  * It is initialized to 1 but will turn to zero if the initialization
  * of the tracer is successful. But that is the only place that sets
@@ -1135,6 +1142,11 @@ void tracing_record_cmdline(struct task_struct *tsk)
 	    !tracing_is_on())
 		return;
 
+	if (!__this_cpu_read(trace_cmdline_save))
+		return;
+
+	__this_cpu_write(trace_cmdline_save, false);
+
 	trace_save_cmdline(tsk);
 }
 
@@ -1178,13 +1190,20 @@ trace_buffer_lock_reserve(struct ring_buffer *buffer,
 	return event;
 }
 
+void
+__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
+{
+	__this_cpu_write(trace_cmdline_save, true);
+	ring_buffer_unlock_commit(buffer, event);
+}
+
 static inline void
 __trace_buffer_unlock_commit(struct ring_buffer *buffer,
 			     struct ring_buffer_event *event,
 			     unsigned long flags, int pc,
 			     int wake)
 {
-	ring_buffer_unlock_commit(buffer, event);
+	__buffer_unlock_commit(buffer, event);
 
 	ftrace_trace_stack(buffer, flags, 6, pc);
 	ftrace_trace_userstack(buffer, flags, pc);
@@ -1232,7 +1251,7 @@ void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
 					    unsigned long flags, int pc,
 					    struct pt_regs *regs)
 {
-	ring_buffer_unlock_commit(buffer, event);
+	__buffer_unlock_commit(buffer, event);
 
 	ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
 	ftrace_trace_userstack(buffer, flags, pc);
@@ -1269,7 +1288,7 @@ trace_function(struct trace_array *tr,
 	entry->parent_ip		= parent_ip;
 
 	if (!filter_check_discard(call, entry, buffer, event))
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 }
 
 void
@@ -1362,7 +1381,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
 	entry->size = trace.nr_entries;
 
 	if (!filter_check_discard(call, entry, buffer, event))
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 
  out:
 	/* Again, don't let gcc optimize things here */
@@ -1458,7 +1477,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
 
 	save_stack_trace_user(&trace);
 	if (!filter_check_discard(call, entry, buffer, event))
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 
  out_drop_count:
 	__this_cpu_dec(user_stack_count);
@@ -1653,7 +1672,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
 
 	memcpy(entry->buf, tbuffer, sizeof(u32) * len);
 	if (!filter_check_discard(call, entry, buffer, event)) {
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 		ftrace_trace_stack(buffer, flags, 6, pc);
 	}
 
@@ -1724,7 +1743,7 @@ int trace_array_vprintk(struct trace_array *tr,
 	memcpy(&entry->buf, tbuffer, len);
 	entry->buf[len] = '\0';
 	if (!filter_check_discard(call, entry, buffer, event)) {
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 		ftrace_trace_stack(buffer, flags, 6, pc);
 	}
  out:
@@ -3993,7 +4012,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	} else
 		entry->buf[cnt] = '\0';
 
-	ring_buffer_unlock_commit(buffer, event);
+	__buffer_unlock_commit(buffer, event);
 
 	written = cnt;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7824a55..839ae00 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -359,6 +359,9 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 					  int *ent_cpu, u64 *ent_ts);
 
+void __buffer_unlock_commit(struct ring_buffer *buffer,
+			    struct ring_buffer_event *event);
+
 int trace_empty(struct trace_iterator *iter);
 
 void *trace_find_next_entry_inc(struct trace_iterator *iter);
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c
index bd3e0ee..95e9684 100644
--- a/kernel/trace/trace_branch.c
+++ b/kernel/trace/trace_branch.c
@@ -77,7 +77,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
 	entry->correct = val == expect;
 
 	if (!filter_check_discard(call, entry, buffer, event))
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 
  out:
 	atomic_dec(&tr->data[cpu]->disabled);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index a84b558..4edb4b7 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -223,7 +223,7 @@ int __trace_graph_entry(struct trace_array *tr,
 	entry	= ring_buffer_event_data(event);
 	entry->graph_ent			= *trace;
 	if (!filter_current_check_discard(buffer, call, entry, event))
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 
 	return 1;
 }
@@ -327,7 +327,7 @@ void __trace_graph_return(struct trace_array *tr,
 	entry	= ring_buffer_event_data(event);
 	entry->ret				= *trace;
 	if (!filter_current_check_discard(buffer, call, entry, event))
-		ring_buffer_unlock_commit(buffer, event);
+		__buffer_unlock_commit(buffer, event);
 }
 
 void trace_graph_return(struct ftrace_graph_ret *trace)
-- 
1.7.10.4



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[PATCH 09/19] tracing: Trivial cleanup

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 2191 bytes --]

From: David Sharp <dhsharp@google.com>

Remove ftrace_format_syscall() declaration; it is neither defined nor
used. Also update a comment and formatting.

Link: http://lkml.kernel.org/r/1339112785-21806-1-git-send-email-vnagarnaik@google.com

Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/trace/syscall.h    |    2 --
 kernel/trace/ring_buffer.c |    6 +++---
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 31966a4..0c95796 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -39,8 +39,6 @@ extern int reg_event_syscall_enter(struct ftrace_event_call *call);
 extern void unreg_event_syscall_enter(struct ftrace_event_call *call);
 extern int reg_event_syscall_exit(struct ftrace_event_call *call);
 extern void unreg_event_syscall_exit(struct ftrace_event_call *call);
-extern int
-ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s);
 enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags,
 				      struct trace_event *event);
 enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags,
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 0ebeb1d..23a384b 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1821,7 +1821,7 @@ rb_add_time_stamp(struct ring_buffer_event *event, u64 delta)
 }
 
 /**
- * ring_buffer_update_event - update event type and data
+ * rb_update_event - update event type and data
  * @event: the even to update
  * @type: the type of event
  * @length: the size of the event field in the ring buffer
@@ -2723,8 +2723,8 @@ EXPORT_SYMBOL_GPL(ring_buffer_discard_commit);
  * and not the length of the event which would hold the header.
  */
 int ring_buffer_write(struct ring_buffer *buffer,
-			unsigned long length,
-			void *data)
+		      unsigned long length,
+		      void *data)
 {
 	struct ring_buffer_per_cpu *cpu_buffer;
 	struct ring_buffer_event *event;
-- 
1.7.10.4



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[PATCH 10/19] tracing: Cleanup unnecessary function declarations

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 5894 bytes --]

From: Vaibhav Nagarnaik <vnagarnaik@google.com>

The functions defined in include/trace/syscalls.h are not used directly
since struct ftrace_event_class was introduced. Remove them from the
header file and rearrange the ftrace_event_class declarations in
trace_syscalls.c.

Link: http://lkml.kernel.org/r/1339112785-21806-2-git-send-email-vnagarnaik@google.com

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/trace/syscall.h       |   21 --------------
 kernel/trace/trace_syscalls.c |   61 ++++++++++++++++++++---------------------
 2 files changed, 29 insertions(+), 53 deletions(-)

diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index 0c95796..84bc419 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -31,25 +31,4 @@ struct syscall_metadata {
 	struct ftrace_event_call *exit_event;
 };
 
-#ifdef CONFIG_FTRACE_SYSCALLS
-extern unsigned long arch_syscall_addr(int nr);
-extern int init_syscall_trace(struct ftrace_event_call *call);
-
-extern int reg_event_syscall_enter(struct ftrace_event_call *call);
-extern void unreg_event_syscall_enter(struct ftrace_event_call *call);
-extern int reg_event_syscall_exit(struct ftrace_event_call *call);
-extern void unreg_event_syscall_exit(struct ftrace_event_call *call);
-enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags,
-				      struct trace_event *event);
-enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags,
-				     struct trace_event *event);
-#endif
-
-#ifdef CONFIG_PERF_EVENTS
-int perf_sysenter_enable(struct ftrace_event_call *call);
-void perf_sysenter_disable(struct ftrace_event_call *call);
-int perf_sysexit_enable(struct ftrace_event_call *call);
-void perf_sysexit_disable(struct ftrace_event_call *call);
-#endif
-
 #endif /* _TRACE_SYSCALL_H */
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 2485a7d..7609dd6 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -21,9 +21,6 @@ static int syscall_enter_register(struct ftrace_event_call *event,
 static int syscall_exit_register(struct ftrace_event_call *event,
 				 enum trace_reg type, void *data);
 
-static int syscall_enter_define_fields(struct ftrace_event_call *call);
-static int syscall_exit_define_fields(struct ftrace_event_call *call);
-
 static struct list_head *
 syscall_get_enter_fields(struct ftrace_event_call *call)
 {
@@ -32,30 +29,6 @@ syscall_get_enter_fields(struct ftrace_event_call *call)
 	return &entry->enter_fields;
 }
 
-struct trace_event_functions enter_syscall_print_funcs = {
-	.trace		= print_syscall_enter,
-};
-
-struct trace_event_functions exit_syscall_print_funcs = {
-	.trace		= print_syscall_exit,
-};
-
-struct ftrace_event_class event_class_syscall_enter = {
-	.system		= "syscalls",
-	.reg		= syscall_enter_register,
-	.define_fields	= syscall_enter_define_fields,
-	.get_fields	= syscall_get_enter_fields,
-	.raw_init	= init_syscall_trace,
-};
-
-struct ftrace_event_class event_class_syscall_exit = {
-	.system		= "syscalls",
-	.reg		= syscall_exit_register,
-	.define_fields	= syscall_exit_define_fields,
-	.fields		= LIST_HEAD_INIT(event_class_syscall_exit.fields),
-	.raw_init	= init_syscall_trace,
-};
-
 extern struct syscall_metadata *__start_syscalls_metadata[];
 extern struct syscall_metadata *__stop_syscalls_metadata[];
 
@@ -432,7 +405,7 @@ void unreg_event_syscall_exit(struct ftrace_event_call *call)
 	mutex_unlock(&syscall_trace_lock);
 }
 
-int init_syscall_trace(struct ftrace_event_call *call)
+static int init_syscall_trace(struct ftrace_event_call *call)
 {
 	int id;
 	int num;
@@ -457,6 +430,30 @@ int init_syscall_trace(struct ftrace_event_call *call)
 	return id;
 }
 
+struct trace_event_functions enter_syscall_print_funcs = {
+	.trace		= print_syscall_enter,
+};
+
+struct trace_event_functions exit_syscall_print_funcs = {
+	.trace		= print_syscall_exit,
+};
+
+struct ftrace_event_class event_class_syscall_enter = {
+	.system		= "syscalls",
+	.reg		= syscall_enter_register,
+	.define_fields	= syscall_enter_define_fields,
+	.get_fields	= syscall_get_enter_fields,
+	.raw_init	= init_syscall_trace,
+};
+
+struct ftrace_event_class event_class_syscall_exit = {
+	.system		= "syscalls",
+	.reg		= syscall_exit_register,
+	.define_fields	= syscall_exit_define_fields,
+	.fields		= LIST_HEAD_INIT(event_class_syscall_exit.fields),
+	.raw_init	= init_syscall_trace,
+};
+
 unsigned long __init __weak arch_syscall_addr(int nr)
 {
 	return (unsigned long)sys_call_table[nr];
@@ -537,7 +534,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 	perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
-int perf_sysenter_enable(struct ftrace_event_call *call)
+static int perf_sysenter_enable(struct ftrace_event_call *call)
 {
 	int ret = 0;
 	int num;
@@ -558,7 +555,7 @@ int perf_sysenter_enable(struct ftrace_event_call *call)
 	return ret;
 }
 
-void perf_sysenter_disable(struct ftrace_event_call *call)
+static void perf_sysenter_disable(struct ftrace_event_call *call)
 {
 	int num;
 
@@ -615,7 +612,7 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 	perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 }
 
-int perf_sysexit_enable(struct ftrace_event_call *call)
+static int perf_sysexit_enable(struct ftrace_event_call *call)
 {
 	int ret = 0;
 	int num;
@@ -636,7 +633,7 @@ int perf_sysexit_enable(struct ftrace_event_call *call)
 	return ret;
 }
 
-void perf_sysexit_disable(struct ftrace_event_call *call)
+static void perf_sysexit_disable(struct ftrace_event_call *call)
 {
 	int num;
 
-- 
1.7.10.4



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[PATCH 11/19] linux/kernel.h: Remove duplicate trace_printk declaration

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 1301 bytes --]

From: Michal Hocko <mhocko@suse.cz>

!CONFIG_TRACING both declares and defines (empty) trace_printk.
The first one is not redundant so it can be removed.

Link: http://lkml.kernel.org/r/1351172511-18125-1-git-send-email-mhocko@suse.cz

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/kernel.h |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index a123b13..7785d5d 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -527,9 +527,6 @@ __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 
 extern void ftrace_dump(enum ftrace_dump_mode oops_dump_mode);
 #else
-static inline __printf(1, 2)
-int trace_printk(const char *fmt, ...);
-
 static inline void tracing_start(void) { }
 static inline void tracing_stop(void) { }
 static inline void ftrace_off_permanent(void) { }
@@ -539,8 +536,8 @@ static inline void tracing_on(void) { }
 static inline void tracing_off(void) { }
 static inline int tracing_is_on(void) { return 0; }
 
-static inline int
-trace_printk(const char *fmt, ...)
+static inline __printf(1, 2)
+int trace_printk(const char *fmt, ...)
 {
 	return 0;
 }
-- 
1.7.10.4



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[PATCH 12/19] tracing: Reset ring buffer when changing trace_clocks

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 1290 bytes --]

From: David Sharp <dhsharp@google.com>

Because the "tsc" clock isn't in nanoseconds, the ring buffer must be
reset when changing clocks so that incomparable timestamps don't end up
in the same trace.

Tested: Confirmed switching clocks resets the trace buffer.

Google-Bug-Id: 6980623
Link: http://lkml.kernel.org/r/1349998076-15495-3-git-send-email-dhsharp@google.com

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 88111b0..6ed6013 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4073,6 +4073,14 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
 	if (max_tr.buffer)
 		ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
 
+	/*
+	 * New clock may not be consistent with the previous clock.
+	 * Reset the buffer so that it doesn't have incomparable timestamps.
+	 */
+	tracing_reset_online_cpus(&global_trace);
+	if (max_tr.buffer)
+		tracing_reset_online_cpus(&max_tr);
+
 	mutex_unlock(&trace_types_lock);
 
 	*fpos += cnt;
-- 
1.7.10.4



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[PATCH 13/19] ring-buffer: Change unsigned long type of ring_buffer_oldest_event_ts() to u64

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 2176 bytes --]

From: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>

ring_buffer_oldest_event_ts() should return a value of u64 type, because
ring_buffer_per_cpu->buffer_page->buffer_data_page->time_stamp is u64 type.

Link: http://lkml.kernel.org/r/1349998076-15495-5-git-send-email-dhsharp@google.com

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ring_buffer.h |    2 +-
 kernel/trace/ring_buffer.c  |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index 2007375..519777e 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -159,7 +159,7 @@ int ring_buffer_record_is_on(struct ring_buffer *buffer);
 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 
-unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
+u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 23a384b..3c7834c 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2932,12 +2932,12 @@ rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer)
  * @buffer: The ring buffer
  * @cpu: The per CPU buffer to read from.
  */
-unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
+u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu)
 {
 	unsigned long flags;
 	struct ring_buffer_per_cpu *cpu_buffer;
 	struct buffer_page *bpage;
-	unsigned long ret;
+	u64 ret;
 
 	if (!cpumask_test_cpu(cpu, buffer->cpumask))
 		return 0;
-- 
1.7.10.4



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[PATCH 14/19] tracing: Separate open function from set_event and available_events

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 3619 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The open function used by available_events is the same as set_event even
though it uses different seq functions. This causes a side effect of
writing into available_events clearing all events, even though
available_events is suppose to be read only.

There's no reason to keep a single function for just the open and have
both use different functions for everything else. It is a little
confusing and causes strange behavior. Just have each have their own
function.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c |   46 +++++++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index dec47e7..cb2df3b 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -491,19 +491,6 @@ static void t_stop(struct seq_file *m, void *p)
 	mutex_unlock(&event_mutex);
 }
 
-static int
-ftrace_event_seq_open(struct inode *inode, struct file *file)
-{
-	const struct seq_operations *seq_ops;
-
-	if ((file->f_mode & FMODE_WRITE) &&
-	    (file->f_flags & O_TRUNC))
-		ftrace_clear_events();
-
-	seq_ops = inode->i_private;
-	return seq_open(file, seq_ops);
-}
-
 static ssize_t
 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 		  loff_t *ppos)
@@ -980,6 +967,9 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	return r;
 }
 
+static int ftrace_event_avail_open(struct inode *inode, struct file *file);
+static int ftrace_event_set_open(struct inode *inode, struct file *file);
+
 static const struct seq_operations show_event_seq_ops = {
 	.start = t_start,
 	.next = t_next,
@@ -995,14 +985,14 @@ static const struct seq_operations show_set_event_seq_ops = {
 };
 
 static const struct file_operations ftrace_avail_fops = {
-	.open = ftrace_event_seq_open,
+	.open = ftrace_event_avail_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = seq_release,
 };
 
 static const struct file_operations ftrace_set_event_fops = {
-	.open = ftrace_event_seq_open,
+	.open = ftrace_event_set_open,
 	.read = seq_read,
 	.write = ftrace_event_write,
 	.llseek = seq_lseek,
@@ -1078,6 +1068,26 @@ static struct dentry *event_trace_events_dir(void)
 	return d_events;
 }
 
+static int
+ftrace_event_avail_open(struct inode *inode, struct file *file)
+{
+	const struct seq_operations *seq_ops = &show_event_seq_ops;
+
+	return seq_open(file, seq_ops);
+}
+
+static int
+ftrace_event_set_open(struct inode *inode, struct file *file)
+{
+	const struct seq_operations *seq_ops = &show_set_event_seq_ops;
+
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (file->f_flags & O_TRUNC))
+		ftrace_clear_events();
+
+	return seq_open(file, seq_ops);
+}
+
 static struct dentry *
 event_subsystem_dir(const char *name, struct dentry *d_events)
 {
@@ -1508,15 +1518,13 @@ static __init int event_trace_init(void)
 		return 0;
 
 	entry = debugfs_create_file("available_events", 0444, d_tracer,
-				    (void *)&show_event_seq_ops,
-				    &ftrace_avail_fops);
+				    NULL, &ftrace_avail_fops);
 	if (!entry)
 		pr_warning("Could not create debugfs "
 			   "'available_events' entry\n");
 
 	entry = debugfs_create_file("set_event", 0644, d_tracer,
-				    (void *)&show_set_event_seq_ops,
-				    &ftrace_set_event_fops);
+				    NULL, &ftrace_set_event_fops);
 	if (!entry)
 		pr_warning("Could not create debugfs "
 			   "'set_event' entry\n");
-- 
1.7.10.4



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[PATCH 15/19] tracing: Remove unused function unregister_tracer()

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 1985 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The function register_tracer() is only used by kernel core code,
that never needs to remove the tracer. As trace_events have become
the main way to add new tracing to the kernel, the need to
unregister a tracer has diminished. Remove the unused function
unregister_tracer(). If a need arises where we need it, then we
can always add it back.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c |   26 --------------------------
 kernel/trace/trace.h |    1 -
 2 files changed, 27 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6ed6013..d1d8039 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -882,32 +882,6 @@ int register_tracer(struct tracer *type)
 	return ret;
 }
 
-void unregister_tracer(struct tracer *type)
-{
-	struct tracer **t;
-
-	mutex_lock(&trace_types_lock);
-	for (t = &trace_types; *t; t = &(*t)->next) {
-		if (*t == type)
-			goto found;
-	}
-	pr_info("Tracer %s not registered\n", type->name);
-	goto out;
-
- found:
-	*t = (*t)->next;
-
-	if (type == current_trace && tracer_enabled) {
-		tracer_enabled = 0;
-		tracing_stop();
-		if (current_trace->stop)
-			current_trace->stop(&global_trace);
-		current_trace = &nop_trace;
-	}
-out:
-	mutex_unlock(&trace_types_lock);
-}
-
 void tracing_reset(struct trace_array *tr, int cpu)
 {
 	struct ring_buffer *buffer = tr->buffer;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 839ae00..3e8a176 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -410,7 +410,6 @@ void tracing_sched_switch_assign_trace(struct trace_array *tr);
 void tracing_stop_sched_switch_record(void);
 void tracing_start_sched_switch_record(void);
 int register_tracer(struct tracer *type);
-void unregister_tracer(struct tracer *type);
 int is_tracing_stopped(void);
 enum trace_file_type {
 	TRACE_FILE_LAT_FMT	= 1,
-- 
1.7.10.4



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[PATCH 16/19] tracing: Make tracing_enabled be equal to tracing_on

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 7891 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

The tracing_enabled file has been deprecated as it never was able
to serve its purpose well. The tracing_on file has taken over.
Instead of having code to keep tracing_enabled, have the tracing_enabled
file just set tracing_on, and remove the tracing_enabled variable.

This allows us to remove the tracing_enabled file. The reason that
the remove is in a different change set and not removed here is
in case we find some lonely userspace tool that requires the file
to exist. Then the removal patch will get reverted, but this one
will not.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c          |   79 +++--------------------------------------
 kernel/trace/trace_selftest.c |   12 -------
 2 files changed, 5 insertions(+), 86 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d1d8039..3c9b96a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -205,20 +205,9 @@ static struct trace_array	max_tr;
 
 static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
 
-/* tracer_enabled is used to toggle activation of a tracer */
-static int			tracer_enabled = 1;
-
-/**
- * tracing_is_enabled - return tracer_enabled status
- *
- * This function is used by other tracers to know the status
- * of the tracer_enabled flag.  Tracers may use this function
- * to know if it should enable their features when starting
- * up. See irqsoff tracer for an example (start_irqsoff_tracer).
- */
 int tracing_is_enabled(void)
 {
-	return tracer_enabled;
+	return tracing_is_on();
 }
 
 /*
@@ -1112,8 +1101,7 @@ void trace_find_cmdline(int pid, char comm[])
 
 void tracing_record_cmdline(struct task_struct *tsk)
 {
-	if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
-	    !tracing_is_on())
+	if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on())
 		return;
 
 	if (!__this_cpu_read(trace_cmdline_save))
@@ -2967,56 +2955,6 @@ static const struct file_operations tracing_saved_cmdlines_fops = {
 };
 
 static ssize_t
-tracing_ctrl_read(struct file *filp, char __user *ubuf,
-		  size_t cnt, loff_t *ppos)
-{
-	char buf[64];
-	int r;
-
-	r = sprintf(buf, "%u\n", tracer_enabled);
-	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
-}
-
-static ssize_t
-tracing_ctrl_write(struct file *filp, const char __user *ubuf,
-		   size_t cnt, loff_t *ppos)
-{
-	struct trace_array *tr = filp->private_data;
-	unsigned long val;
-	int ret;
-
-	ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
-	if (ret)
-		return ret;
-
-	val = !!val;
-
-	mutex_lock(&trace_types_lock);
-	if (tracer_enabled ^ val) {
-
-		/* Only need to warn if this is used to change the state */
-		WARN_ONCE(1, "tracing_enabled is deprecated. Use tracing_on");
-
-		if (val) {
-			tracer_enabled = 1;
-			if (current_trace->start)
-				current_trace->start(tr);
-			tracing_start();
-		} else {
-			tracer_enabled = 0;
-			tracing_stop();
-			if (current_trace->stop)
-				current_trace->stop(tr);
-		}
-	}
-	mutex_unlock(&trace_types_lock);
-
-	*ppos += cnt;
-
-	return cnt;
-}
-
-static ssize_t
 tracing_set_trace_read(struct file *filp, char __user *ubuf,
 		       size_t cnt, loff_t *ppos)
 {
@@ -3469,7 +3407,7 @@ static int tracing_wait_pipe(struct file *filp)
 			return -EINTR;
 
 		/*
-		 * We block until we read something and tracing is disabled.
+		 * We block until we read something and tracing is enabled.
 		 * We still block if tracing is disabled, but we have never
 		 * read anything. This allows a user to cat this file, and
 		 * then enable tracing. But after we have read something,
@@ -3477,7 +3415,7 @@ static int tracing_wait_pipe(struct file *filp)
 		 *
 		 * iter->pos will be 0 if we haven't read anything.
 		 */
-		if (!tracer_enabled && iter->pos)
+		if (tracing_is_enabled() && iter->pos)
 			break;
 	}
 
@@ -4076,13 +4014,6 @@ static const struct file_operations tracing_max_lat_fops = {
 	.llseek		= generic_file_llseek,
 };
 
-static const struct file_operations tracing_ctrl_fops = {
-	.open		= tracing_open_generic,
-	.read		= tracing_ctrl_read,
-	.write		= tracing_ctrl_write,
-	.llseek		= generic_file_llseek,
-};
-
 static const struct file_operations set_tracer_fops = {
 	.open		= tracing_open_generic,
 	.read		= tracing_set_trace_read,
@@ -4858,7 +4789,7 @@ static __init int tracer_init_debugfs(void)
 	d_tracer = tracing_init_dentry();
 
 	trace_create_file("tracing_enabled", 0644, d_tracer,
-			&global_trace, &tracing_ctrl_fops);
+			  &global_trace, &rb_simple_fops);
 
 	trace_create_file("trace_options", 0644, d_tracer,
 			NULL, &tracing_iter_fops);
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 2c00a69..091b815 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -320,7 +320,6 @@ int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 					   int (*func)(void))
 {
 	int save_ftrace_enabled = ftrace_enabled;
-	int save_tracer_enabled = tracer_enabled;
 	unsigned long count;
 	char *func_name;
 	int ret;
@@ -331,7 +330,6 @@ int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 
 	/* enable tracing, and record the filter function */
 	ftrace_enabled = 1;
-	tracer_enabled = 1;
 
 	/* passed in by parameter to fool gcc from optimizing */
 	func();
@@ -395,7 +393,6 @@ int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 
  out:
 	ftrace_enabled = save_ftrace_enabled;
-	tracer_enabled = save_tracer_enabled;
 
 	/* Enable tracing on all functions again */
 	ftrace_set_global_filter(NULL, 0, 1);
@@ -452,7 +449,6 @@ static int
 trace_selftest_function_recursion(void)
 {
 	int save_ftrace_enabled = ftrace_enabled;
-	int save_tracer_enabled = tracer_enabled;
 	char *func_name;
 	int len;
 	int ret;
@@ -465,7 +461,6 @@ trace_selftest_function_recursion(void)
 
 	/* enable tracing, and record the filter function */
 	ftrace_enabled = 1;
-	tracer_enabled = 1;
 
 	/* Handle PPC64 '.' name */
 	func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
@@ -534,7 +529,6 @@ trace_selftest_function_recursion(void)
 	ret = 0;
 out:
 	ftrace_enabled = save_ftrace_enabled;
-	tracer_enabled = save_tracer_enabled;
 
 	return ret;
 }
@@ -569,7 +563,6 @@ static int
 trace_selftest_function_regs(void)
 {
 	int save_ftrace_enabled = ftrace_enabled;
-	int save_tracer_enabled = tracer_enabled;
 	char *func_name;
 	int len;
 	int ret;
@@ -586,7 +579,6 @@ trace_selftest_function_regs(void)
 
 	/* enable tracing, and record the filter function */
 	ftrace_enabled = 1;
-	tracer_enabled = 1;
 
 	/* Handle PPC64 '.' name */
 	func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
@@ -648,7 +640,6 @@ trace_selftest_function_regs(void)
 	ret = 0;
 out:
 	ftrace_enabled = save_ftrace_enabled;
-	tracer_enabled = save_tracer_enabled;
 
 	return ret;
 }
@@ -662,7 +653,6 @@ int
 trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 {
 	int save_ftrace_enabled = ftrace_enabled;
-	int save_tracer_enabled = tracer_enabled;
 	unsigned long count;
 	int ret;
 
@@ -671,7 +661,6 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 
 	/* start the tracing */
 	ftrace_enabled = 1;
-	tracer_enabled = 1;
 
 	ret = tracer_init(trace, tr);
 	if (ret) {
@@ -708,7 +697,6 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 	ret = trace_selftest_function_regs();
  out:
 	ftrace_enabled = save_ftrace_enabled;
-	tracer_enabled = save_tracer_enabled;
 
 	/* kill ftrace totally if we failed */
 	if (ret)
-- 
1.7.10.4



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[PATCH 17/19] tracing: Remove deprecated tracing_enabled file

[Steven Rostedt]

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From: Steven Rostedt <srostedt@redhat.com>

The tracing_enabled file was used as a quick way to stop
tracers, and try to bring down overhead for things like
the latency tracers (irqsoff, wakeup, etc). But it didn't
work that well.

The tracing_on file was created as a really fast way to
stop recording into the ftrace ring buffer and can interact
with the kernel. That is a tracing_off() call in the kernel
can disable recording of events, and then from userspace one
could echo 1 into the tracing_on file to continue it. The
tracing_enabled function did too much to allow for this.

The tracing_on has taken over as a way to start and stop tracing
and the tracing_enabled file should not be used. But because of
its existance, it still confuses people. Over a year ago the
following commit was added:

 commit 6752ab4a9c30d5411b2dfdb251a3f1cb18aae487
 Author: Steven Rostedt <srostedt@redhat.com>
 Date:   Tue Feb 8 13:54:06 2011 -0500

    tracing: Deprecate tracing_enabled for tracing_on

This commit added a WARN_ON() if the tracing_enabled file's variable
was changed. After this was added, only LatencyTop complained, and
they soon fixed their tool as there was no reason that LatencyTop
should touch this file as it was using the perf ring buffers which
this file does not interact with. But since that time no one else
has complained about this WARN_ON(). Thus it is safe to assume that
this file is no longer needed. Time to get rid of it.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c |    3 ---
 1 file changed, 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3c9b96a..d5cbc0d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4788,9 +4788,6 @@ static __init int tracer_init_debugfs(void)
 
 	d_tracer = tracing_init_dentry();
 
-	trace_create_file("tracing_enabled", 0644, d_tracer,
-			  &global_trace, &rb_simple_fops);
-
 	trace_create_file("trace_options", 0644, d_tracer,
 			NULL, &tracing_iter_fops);
 
-- 
1.7.10.4



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[PATCH 18/19] tracing: Use irq_work for wake ups and remove *_nowake_*() functions

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 14135 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Have the ring buffer commit function use the irq_work infrastructure to
wake up any waiters waiting on the ring buffer for new data. The irq_work
was created for such a purpose, where doing the actual wake up at the
time of adding data is too dangerous, as an event or function trace may
be in the midst of the work queue locks and cause deadlocks. The irq_work
will either delay the action to the next timer interrupt, or trigger an IPI
to itself forcing an interrupt to do the work (in a safe location).

With irq_work, all ring buffer commits can safely do wakeups, removing
the need for the ring buffer commit "nowake" variants, which were used
by events and function tracing. All commits can now safely use the
normal commit, and the "nowake" variants can be removed.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace_event.h      |   14 ++---
 include/trace/ftrace.h            |    3 +-
 kernel/trace/Kconfig              |    1 +
 kernel/trace/trace.c              |  121 +++++++++++++++++++++----------------
 kernel/trace/trace.h              |    5 --
 kernel/trace/trace_events.c       |    2 +-
 kernel/trace/trace_kprobe.c       |    8 +--
 kernel/trace/trace_sched_switch.c |    2 +-
 kernel/trace/trace_selftest.c     |    1 +
 9 files changed, 84 insertions(+), 73 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 642928c..b80c8dd 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -127,13 +127,13 @@ trace_current_buffer_lock_reserve(struct ring_buffer **current_buffer,
 void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
 					struct ring_buffer_event *event,
 					unsigned long flags, int pc);
-void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
-				       struct ring_buffer_event *event,
-					unsigned long flags, int pc);
-void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
-					    struct ring_buffer_event *event,
-					    unsigned long flags, int pc,
-					    struct pt_regs *regs);
+void trace_buffer_unlock_commit(struct ring_buffer *buffer,
+				struct ring_buffer_event *event,
+				unsigned long flags, int pc);
+void trace_buffer_unlock_commit_regs(struct ring_buffer *buffer,
+				     struct ring_buffer_event *event,
+				     unsigned long flags, int pc,
+				     struct pt_regs *regs);
 void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
 					 struct ring_buffer_event *event);
 
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index a763888..698f2a8 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -545,8 +545,7 @@ ftrace_raw_event_##call(void *__data, proto)				\
 	{ assign; }							\
 									\
 	if (!filter_current_check_discard(buffer, event_call, entry, event)) \
-		trace_nowake_buffer_unlock_commit(buffer,		\
-						  event, irq_flags, pc); \
+		trace_buffer_unlock_commit(buffer, event, irq_flags, pc); \
 }
 /*
  * The ftrace_test_probe is compiled out, it is only here as a build time check
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 4cea4f4..5d89335 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -119,6 +119,7 @@ config TRACING
 	select BINARY_PRINTF
 	select EVENT_TRACING
 	select TRACE_CLOCK
+	select IRQ_WORK
 
 config GENERIC_TRACER
 	bool
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d5cbc0d..37d1c70 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -19,6 +19,7 @@
 #include <linux/seq_file.h>
 #include <linux/notifier.h>
 #include <linux/irqflags.h>
+#include <linux/irq_work.h>
 #include <linux/debugfs.h>
 #include <linux/pagemap.h>
 #include <linux/hardirq.h>
@@ -85,6 +86,14 @@ static int dummy_set_flag(u32 old_flags, u32 bit, int set)
 static DEFINE_PER_CPU(bool, trace_cmdline_save);
 
 /*
+ * When a reader is waiting for data, then this variable is
+ * set to true.
+ */
+static bool trace_wakeup_needed;
+
+static struct irq_work trace_work_wakeup;
+
+/*
  * Kill all tracing for good (never come back).
  * It is initialized to 1 but will turn to zero if the initialization
  * of the tracer is successful. But that is the only place that sets
@@ -329,12 +338,18 @@ unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
 static int trace_stop_count;
 static DEFINE_RAW_SPINLOCK(tracing_start_lock);
 
-static void wakeup_work_handler(struct work_struct *work)
+/**
+ * trace_wake_up - wake up tasks waiting for trace input
+ *
+ * Schedules a delayed work to wake up any task that is blocked on the
+ * trace_wait queue. These is used with trace_poll for tasks polling the
+ * trace.
+ */
+static void trace_wake_up(struct irq_work *work)
 {
-	wake_up(&trace_wait);
-}
+	wake_up_all(&trace_wait);
 
-static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
+}
 
 /**
  * tracing_on - enable tracing buffers
@@ -389,22 +404,6 @@ int tracing_is_on(void)
 }
 EXPORT_SYMBOL_GPL(tracing_is_on);
 
-/**
- * trace_wake_up - wake up tasks waiting for trace input
- *
- * Schedules a delayed work to wake up any task that is blocked on the
- * trace_wait queue. These is used with trace_poll for tasks polling the
- * trace.
- */
-void trace_wake_up(void)
-{
-	const unsigned long delay = msecs_to_jiffies(2);
-
-	if (trace_flags & TRACE_ITER_BLOCK)
-		return;
-	schedule_delayed_work(&wakeup_work, delay);
-}
-
 static int __init set_buf_size(char *str)
 {
 	unsigned long buf_size;
@@ -753,6 +752,40 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 }
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
+static void default_wait_pipe(struct trace_iterator *iter)
+{
+	DEFINE_WAIT(wait);
+
+	prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
+
+	/*
+	 * The events can happen in critical sections where
+	 * checking a work queue can cause deadlocks.
+	 * After adding a task to the queue, this flag is set
+	 * only to notify events to try to wake up the queue
+	 * using irq_work.
+	 *
+	 * We don't clear it even if the buffer is no longer
+	 * empty. The flag only causes the next event to run
+	 * irq_work to do the work queue wake up. The worse
+	 * that can happen if we race with !trace_empty() is that
+	 * an event will cause an irq_work to try to wake up
+	 * an empty queue.
+	 *
+	 * There's no reason to protect this flag either, as
+	 * the work queue and irq_work logic will do the necessary
+	 * synchronization for the wake ups. The only thing
+	 * that is necessary is that the wake up happens after
+	 * a task has been queued. It's OK for spurious wake ups.
+	 */
+	trace_wakeup_needed = true;
+
+	if (trace_empty(iter))
+		schedule();
+
+	finish_wait(&trace_wait, &wait);
+}
+
 /**
  * register_tracer - register a tracer with the ftrace system.
  * @type - the plugin for the tracer
@@ -1156,30 +1189,32 @@ void
 __buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
 {
 	__this_cpu_write(trace_cmdline_save, true);
+	if (trace_wakeup_needed) {
+		trace_wakeup_needed = false;
+		/* irq_work_queue() supplies it's own memory barriers */
+		irq_work_queue(&trace_work_wakeup);
+	}
 	ring_buffer_unlock_commit(buffer, event);
 }
 
 static inline void
 __trace_buffer_unlock_commit(struct ring_buffer *buffer,
 			     struct ring_buffer_event *event,
-			     unsigned long flags, int pc,
-			     int wake)
+			     unsigned long flags, int pc)
 {
 	__buffer_unlock_commit(buffer, event);
 
 	ftrace_trace_stack(buffer, flags, 6, pc);
 	ftrace_trace_userstack(buffer, flags, pc);
-
-	if (wake)
-		trace_wake_up();
 }
 
 void trace_buffer_unlock_commit(struct ring_buffer *buffer,
 				struct ring_buffer_event *event,
 				unsigned long flags, int pc)
 {
-	__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
+	__trace_buffer_unlock_commit(buffer, event, flags, pc);
 }
+EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit);
 
 struct ring_buffer_event *
 trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
@@ -1196,29 +1231,21 @@ void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
 					struct ring_buffer_event *event,
 					unsigned long flags, int pc)
 {
-	__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
+	__trace_buffer_unlock_commit(buffer, event, flags, pc);
 }
 EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
 
-void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
-				       struct ring_buffer_event *event,
-				       unsigned long flags, int pc)
-{
-	__trace_buffer_unlock_commit(buffer, event, flags, pc, 0);
-}
-EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
-
-void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
-					    struct ring_buffer_event *event,
-					    unsigned long flags, int pc,
-					    struct pt_regs *regs)
+void trace_buffer_unlock_commit_regs(struct ring_buffer *buffer,
+				     struct ring_buffer_event *event,
+				     unsigned long flags, int pc,
+				     struct pt_regs *regs)
 {
 	__buffer_unlock_commit(buffer, event);
 
 	ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
 	ftrace_trace_userstack(buffer, flags, pc);
 }
-EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit_regs);
+EXPORT_SYMBOL_GPL(trace_buffer_unlock_commit_regs);
 
 void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
 					 struct ring_buffer_event *event)
@@ -3354,19 +3381,6 @@ 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:
@@ -5107,6 +5121,7 @@ __init static int tracer_alloc_buffers(void)
 #endif
 
 	trace_init_cmdlines();
+	init_irq_work(&trace_work_wakeup, trace_wake_up);
 
 	register_tracer(&nop_trace);
 	current_trace = &nop_trace;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3e8a176..55010ed 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -327,7 +327,6 @@ trace_buffer_iter(struct trace_iterator *iter, int cpu)
 
 int tracer_init(struct tracer *t, struct trace_array *tr);
 int tracing_is_enabled(void);
-void trace_wake_up(void);
 void tracing_reset(struct trace_array *tr, int cpu);
 void tracing_reset_online_cpus(struct trace_array *tr);
 void tracing_reset_current(int cpu);
@@ -349,9 +348,6 @@ trace_buffer_lock_reserve(struct ring_buffer *buffer,
 			  unsigned long len,
 			  unsigned long flags,
 			  int pc);
-void trace_buffer_unlock_commit(struct ring_buffer *buffer,
-				struct ring_buffer_event *event,
-				unsigned long flags, int pc);
 
 struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 						struct trace_array_cpu *data);
@@ -370,7 +366,6 @@ void trace_init_global_iter(struct trace_iterator *iter);
 
 void tracing_iter_reset(struct trace_iterator *iter, int cpu);
 
-void default_wait_pipe(struct trace_iterator *iter);
 void poll_wait_pipe(struct trace_iterator *iter);
 
 void ftrace(struct trace_array *tr,
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index cb2df3b..880073d 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1760,7 +1760,7 @@ function_test_events_call(unsigned long ip, unsigned long parent_ip,
 	entry->ip			= ip;
 	entry->parent_ip		= parent_ip;
 
-	trace_nowake_buffer_unlock_commit(buffer, event, flags, pc);
+	trace_buffer_unlock_commit(buffer, event, flags, pc);
 
  out:
 	atomic_dec(&per_cpu(ftrace_test_event_disable, cpu));
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5a3c533..1865d5f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -751,8 +751,8 @@ static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 	store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
 	if (!filter_current_check_discard(buffer, call, entry, event))
-		trace_nowake_buffer_unlock_commit_regs(buffer, event,
-						       irq_flags, pc, regs);
+		trace_buffer_unlock_commit_regs(buffer, event,
+						irq_flags, pc, regs);
 }
 
 /* Kretprobe handler */
@@ -784,8 +784,8 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
 	store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
 	if (!filter_current_check_discard(buffer, call, entry, event))
-		trace_nowake_buffer_unlock_commit_regs(buffer, event,
-						       irq_flags, pc, regs);
+		trace_buffer_unlock_commit_regs(buffer, event,
+						irq_flags, pc, regs);
 }
 
 /* Event entry printers */
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index b0a136a..3374c79 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -102,7 +102,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
 	entry->next_cpu			= task_cpu(wakee);
 
 	if (!filter_check_discard(call, entry, buffer, event))
-		trace_nowake_buffer_unlock_commit(buffer, event, flags, pc);
+		trace_buffer_unlock_commit(buffer, event, flags, pc);
 }
 
 static void
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 091b815..4762316 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -1094,6 +1094,7 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
 	tracing_stop();
 	/* check both trace buffers */
 	ret = trace_test_buffer(tr, NULL);
+	printk("ret = %d\n", ret);
 	if (!ret)
 		ret = trace_test_buffer(&max_tr, &count);
 
-- 
1.7.10.4



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[PATCH 19/19] tracing: Add trace_options kernel command line parameter

[Steven Rostedt]

[-- Attachment #1: Type: text/plain, Size: 4004 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Add trace_options to the kernel command line parameter to be able to
set options at early boot. For example, to enable stack dumps of
events, add the following:

  trace_options=stacktrace

This along with the trace_event option, you can get not only
traces of the events but also the stack dumps with them.

Requested-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 Documentation/kernel-parameters.txt |   16 +++++++++++
 kernel/trace/trace.c                |   54 +++++++++++++++++++++++++----------
 2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9776f06..2b48c52 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2859,6 +2859,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			to facilitate early boot debugging.
 			See also Documentation/trace/events.txt
 
+	trace_options=[option-list]
+			[FTRACE] Enable or disable tracer options at boot.
+			The option-list is a comma delimited list of options
+			that can be enabled or disabled just as if you were
+			to echo the option name into
+
+			    /sys/kernel/debug/tracing/trace_options
+
+			For example, to enable stacktrace option (to dump the
+			stack trace of each event), add to the command line:
+
+			      trace_options=stacktrace
+
+			See also Documentation/trace/ftrace.txt "trace options"
+			section.
+
 	transparent_hugepage=
 			[KNL]
 			Format: [always|madvise|never]
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 37d1c70..c1434b5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -155,6 +155,18 @@ static int __init set_ftrace_dump_on_oops(char *str)
 }
 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
 
+
+static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
+static char *trace_boot_options __initdata;
+
+static int __init set_trace_boot_options(char *str)
+{
+	strncpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
+	trace_boot_options = trace_boot_options_buf;
+	return 0;
+}
+__setup("trace_options=", set_trace_boot_options);
+
 unsigned long long ns2usecs(cycle_t nsec)
 {
 	nsec += 500;
@@ -2838,24 +2850,14 @@ static void set_tracer_flags(unsigned int mask, int enabled)
 		trace_printk_start_stop_comm(enabled);
 }
 
-static ssize_t
-tracing_trace_options_write(struct file *filp, const char __user *ubuf,
-			size_t cnt, loff_t *ppos)
+static int trace_set_options(char *option)
 {
-	char buf[64];
 	char *cmp;
 	int neg = 0;
-	int ret;
+	int ret = 0;
 	int i;
 
-	if (cnt >= sizeof(buf))
-		return -EINVAL;
-
-	if (copy_from_user(&buf, ubuf, cnt))
-		return -EFAULT;
-
-	buf[cnt] = 0;
-	cmp = strstrip(buf);
+	cmp = strstrip(option);
 
 	if (strncmp(cmp, "no", 2) == 0) {
 		neg = 1;
@@ -2874,10 +2876,25 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 		mutex_lock(&trace_types_lock);
 		ret = set_tracer_option(current_trace, cmp, neg);
 		mutex_unlock(&trace_types_lock);
-		if (ret)
-			return ret;
 	}
 
+	return ret;
+}
+
+static ssize_t
+tracing_trace_options_write(struct file *filp, const char __user *ubuf,
+			size_t cnt, loff_t *ppos)
+{
+	char buf[64];
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	trace_set_options(buf);
+
 	*ppos += cnt;
 
 	return cnt;
@@ -5133,6 +5150,13 @@ __init static int tracer_alloc_buffers(void)
 
 	register_die_notifier(&trace_die_notifier);
 
+	while (trace_boot_options) {
+		char *option;
+
+		option = strsep(&trace_boot_options, ",");
+		trace_set_options(option);
+	}
+
 	return 0;
 
 out_free_cpumask:
-- 
1.7.10.4



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Re: [PATCH 00/19] [GIT PULL][3.8] tracing: updates (v2)

[Steven Rostedt]

On Fri, 2012-11-02 at 14:13 -0400, Steven Rostedt wrote:
> Ingo,
> 
> I removed the few problem patches (and their dependencies) and
> retested the result.
> 
> Please pull the latest tip/perf/core-2 tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> tip/perf/core-2
> 
> Head SHA1: 7bcfaf54f591a0775254c4ea679faf615152ee3a
> 

Hi Ingo,

Any hold up for pulling this patch set into tip?

-- Steve

> 
> Daniel Walter (1):
>       tracing: Replace strict_strto* with kstrto*
> 
> David Sharp (2):
>       tracing: Trivial cleanup
>       tracing: Reset ring buffer when changing trace_clocks
> 
> Hiraku Toyooka (1):
>       tracing: Change tracer's integer flags to bool
> 
> Michal Hocko (1):
>       linux/kernel.h: Remove duplicate trace_printk declaration
> 
> Slava Pestov (1):
>       ring-buffer: Add a 'dropped events' counter
> 
> Steven Rostedt (11):
>       tracing: Allow tracers to start at core initcall
>       tracing: Expand ring buffer when trace_printk() is used
>       tracing: Enable comm recording if trace_printk() is used
>       tracing: Have tracing_sched_wakeup_trace() use standard unlock_commit
>       tracing: Cache comms only after an event occurred
>       tracing: Separate open function from set_event and available_events
>       tracing: Remove unused function unregister_tracer()
>       tracing: Make tracing_enabled be equal to tracing_on
>       tracing: Remove deprecated tracing_enabled file
>       tracing: Use irq_work for wake ups and remove *_nowake_*() functions
>       tracing: Add trace_options kernel command line parameter
> 
> Vaibhav Nagarnaik (1):
>       tracing: Cleanup unnecessary function declarations
> 
> Yoshihiro YUNOMAE (1):
>       ring-buffer: Change unsigned long type of ring_buffer_oldest_event_ts() to u64
> 
> ----
>  Documentation/kernel-parameters.txt  |   16 ++
>  include/linux/ftrace_event.h         |   14 +-
>  include/linux/kernel.h               |    7 +-
>  include/linux/ring_buffer.h          |    3 +-
>  include/trace/ftrace.h               |    3 +-
>  include/trace/syscall.h              |   23 ---
>  kernel/trace/Kconfig                 |    1 +
>  kernel/trace/ftrace.c                |    6 +-
>  kernel/trace/ring_buffer.c           |   51 ++++-
>  kernel/trace/trace.c                 |  372 +++++++++++++++++-----------------
>  kernel/trace/trace.h                 |   14 +-
>  kernel/trace/trace_branch.c          |    4 +-
>  kernel/trace/trace_events.c          |   51 +++--
>  kernel/trace/trace_events_filter.c   |    4 +-
>  kernel/trace/trace_functions.c       |    5 +-
>  kernel/trace/trace_functions_graph.c |    6 +-
>  kernel/trace/trace_irqsoff.c         |   14 +-
>  kernel/trace/trace_kprobe.c          |   10 +-
>  kernel/trace/trace_probe.c           |   14 +-
>  kernel/trace/trace_sched_switch.c    |    4 +-
>  kernel/trace/trace_sched_wakeup.c    |   10 +-
>  kernel/trace/trace_selftest.c        |   13 +-
>  kernel/trace/trace_syscalls.c        |   61 +++---
>  kernel/trace/trace_uprobe.c          |    2 +-
>  24 files changed, 365 insertions(+), 343 deletions(-)

Re: [PATCH 00/19] [GIT PULL][3.8] tracing: updates (v2)

[Ingo Molnar]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Fri, 2012-11-02 at 14:13 -0400, Steven Rostedt wrote:
> > Ingo,
> > 
> > I removed the few problem patches (and their dependencies) and
> > retested the result.
> > 
> > Please pull the latest tip/perf/core-2 tree, which can be found at:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> > tip/perf/core-2
> > 
> > Head SHA1: 7bcfaf54f591a0775254c4ea679faf615152ee3a
> > 
> 
> Hi Ingo,
> 
> Any hold up for pulling this patch set into tip?

No, it's looking good, I've pulled it, thanks Steve!

	Ingo