tracing: Remove unused ftrace_cpu_disabled per cpu variable

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>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 08af79c106e114c284517dfda2708d4f6c36b879..b115826189917f669b8fa714ae332d852616639b 100644 (file)
--- 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 dd7620802e725e1e2f262f77ba7d8c76dda98ef9..919d9d07686f5bcaad65699f400748a4b4db8a5e 100644 (file)
--- 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 92382af7a21312c03ecef0cabdfbce19e2c8111e..a663cbb84107d71039200011e4b3ec5f897c9213 100644 (file)
--- 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)