[for-next][PATCH 0/2] tracing: A couple of cleanups for 4.4

[for-next][PATCH 0/2] tracing: A couple of cleanups for 4.4

[Steven Rostedt]

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next

Head SHA1: 03e88ae6b369da2a26a6e09ad165e57d210789cd


Dmitry Safonov (1):
      tracing: Remove unused ftrace_cpu_disabled per cpu variable

Jiaxing Wang (1):
      tracing: Make tracing work when debugfs is not configured in

----
 kernel/trace/trace.c                 | 10 +++-------
 kernel/trace/trace.h                 |  1 -
 kernel/trace/trace_functions_graph.c |  6 ------
 3 files changed, 3 insertions(+), 14 deletions(-)

[for-next][PATCH 1/2] tracing: Make tracing work when debugfs is not configured in

[Steven Rostedt]

[-- Attachment #1: 0001-tracing-Make-tracing-work-when-debugfs-is-not-config.patch --]
[-- Type: text/plain, Size: 1263 bytes --]

From: Jiaxing Wang <hello.wjx@gmail.com>

Currently tracing_init_dentry() returns -ENODEV when debugfs is not
configured in, which causes tracefs not populated with tracing files and
directories, so we will get an empty directory even after we manually
mount tracefs.

We can make tracing_init_dentry() return NULL if debugfs is not
configured in and can manually mount tracefs. But return -ENODEV
if debugfs is configured in but not initialized or failed to create
automount point as that would break backward compatibility with older
tools.

Link: http://lkml.kernel.org/r/1446797056-11683-1-git-send-email-hello.wjx@gmail.com

Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2198a630ef58..08af79c106e1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6847,7 +6847,9 @@ struct dentry *tracing_init_dentry(void)
 	if (tr->dir)
 		return NULL;
 
-	if (WARN_ON(!debugfs_initialized()))
+	if (WARN_ON(!tracefs_initialized()) ||
+		(IS_ENABLED(CONFIG_DEBUG_FS) &&
+		 WARN_ON(!debugfs_initialized())))
 		return ERR_PTR(-ENODEV);
 
 	/*
-- 
2.6.1

[for-next][PATCH 2/2] tracing: Remove unused ftrace_cpu_disabled per cpu variable

[Steven Rostedt]

[-- Attachment #1: 0002-tracing-Remove-unused-ftrace_cpu_disabled-per-cpu-va.patch --]
[-- Type: text/plain, Size: 2888 bytes --]

From: Dmitry Safonov <0x7f454c46@gmail.com>

Since the ring buffer is lockless, there is no need to disable ftrace on
CPU. And no one doing so: after commit 68179686ac67cb ("tracing: Remove
ftrace_disable/enable_cpu()") ftrace_cpu_disabled stays the same after
initialization, nothing changes it.
ftrace_cpu_disabled shouldn't be used by any external module since it
disables only function and graph_function tracers but not any other
tracer.

Link: http://lkml.kernel.org/r/1446836846-22239-1-git-send-email-0x7f454c46@gmail.com

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c                 | 6 ------
 kernel/trace/trace.h                 | 1 -
 kernel/trace/trace_functions_graph.c | 6 ------
 3 files changed, 13 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 08af79c106e1..b11582618991 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -100,8 +100,6 @@ static DEFINE_PER_CPU(bool, trace_cmdline_save);
  */
 static int tracing_disabled = 1;
 
-DEFINE_PER_CPU(int, ftrace_cpu_disabled);
-
 cpumask_var_t __read_mostly	tracing_buffer_mask;
 
 /*
@@ -1775,10 +1773,6 @@ trace_function(struct trace_array *tr,
 	struct ring_buffer_event *event;
 	struct ftrace_entry *entry;
 
-	/* If we are reading the ring buffer, don't trace */
-	if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
-		return;
-
 	event = trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
 					  flags, pc);
 	if (!event)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index dd7620802e72..919d9d07686f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -667,7 +667,6 @@ extern int DYN_FTRACE_TEST_NAME2(void);
 
 extern bool ring_buffer_expanded;
 extern bool tracing_selftest_disabled;
-DECLARE_PER_CPU(int, ftrace_cpu_disabled);
 
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 extern int trace_selftest_startup_function(struct tracer *trace,
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 92382af7a213..a663cbb84107 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -288,9 +288,6 @@ int __trace_graph_entry(struct trace_array *tr,
 	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ftrace_graph_ent_entry *entry;
 
-	if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
-		return 0;
-
 	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
 					  sizeof(*entry), flags, pc);
 	if (!event)
@@ -403,9 +400,6 @@ void __trace_graph_return(struct trace_array *tr,
 	struct ring_buffer *buffer = tr->trace_buffer.buffer;
 	struct ftrace_graph_ret_entry *entry;
 
-	if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
-		return;
-
 	event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
 					  sizeof(*entry), flags, pc);
 	if (!event)
-- 
2.6.1