6 files changed, 120 insertions, 48 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 113aea9447ec..ff1e9ed9b587 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -150,6 +150,19 @@ static DEFINE_PER_CPU(struct trace_array_cpu, max_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;
+}
+
 /* function tracing enabled */
 int                             ftrace_function_enabled;
 
@@ -1041,8 +1054,7 @@ void tracing_start_function_trace(void)
                 trace_ops.func = function_trace_call;
 
         register_ftrace_function(&trace_ops);
-        if (tracer_enabled)
-                ftrace_function_enabled = 1;
+        ftrace_function_enabled = 1;
 }
 
 void tracing_stop_function_trace(void)
@@ -1189,10 +1201,6 @@ static void *s_start(struct seq_file *m, loff_t *pos)
 
         atomic_inc(&trace_record_cmdline_disabled);
 
-        /* let the tracer grab locks here if needed */
-        if (current_trace->start)
-                current_trace->start(iter);
-
         if (*pos != iter->pos) {
                 iter->ent = NULL;
                 iter->cpu = 0;
@@ -1219,14 +1227,7 @@ static void *s_start(struct seq_file *m, loff_t *pos)
 
 static void s_stop(struct seq_file *m, void *p)
 {
-        struct trace_iterator *iter = m->private;
-
         atomic_dec(&trace_record_cmdline_disabled);
-
-        /* let the tracer release locks here if needed */
-        if (current_trace && current_trace == iter->trace && iter->trace->stop)
-                iter->trace->stop(iter);
-
         mutex_unlock(&trace_types_lock);
 }
 
@@ -2056,10 +2057,7 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
         m->private = iter;
 
         /* stop the trace while dumping */
-        if (iter->tr->ctrl) {
-                tracer_enabled = 0;
-                ftrace_function_enabled = 0;
-        }
+        tracing_stop();
 
         if (iter->trace && iter->trace->open)
                         iter->trace->open(iter);
@@ -2104,14 +2102,7 @@ int tracing_release(struct inode *inode, struct file *file)
                 iter->trace->close(iter);
 
         /* reenable tracing if it was previously enabled */
-        if (iter->tr->ctrl) {
-                tracer_enabled = 1;
-                /*
-                 * It is safe to enable function tracing even if it
-                 * isn't used
-                 */
-                ftrace_function_enabled = 1;
-        }
+        tracing_start();
         mutex_unlock(&trace_types_lock);
 
         seq_release(inode, file);
@@ -2449,11 +2440,10 @@ static ssize_t
 tracing_ctrl_read(struct file *filp, char __user *ubuf,
                   size_t cnt, loff_t *ppos)
 {
-        struct trace_array *tr = filp->private_data;
         char buf[64];
         int r;
 
-        r = sprintf(buf, "%ld\n", tr->ctrl);
+        r = sprintf(buf, "%u\n", tracer_enabled);
         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
 
@@ -2481,16 +2471,18 @@ tracing_ctrl_write(struct file *filp, const char __user *ubuf,
         val = !!val;
 
         mutex_lock(&trace_types_lock);
-        if (tr->ctrl ^ val) {
-                if (val)
+        if (tracer_enabled ^ val) {
+                if (val) {
                         tracer_enabled = 1;
-                else
+                        if (current_trace->start)
+                                current_trace->start(tr);
+                        tracing_start();
+                } else {
                         tracer_enabled = 0;
-
-                tr->ctrl = val;
-
-                if (current_trace && current_trace->ctrl_update)
-                        current_trace->ctrl_update(tr);
+                        tracing_stop();
+                        if (current_trace->stop)
+                                current_trace->stop(tr);
+                }
         }
         mutex_unlock(&trace_types_lock);
 
@@ -3372,7 +3364,7 @@ __init static int tracer_alloc_buffers(void)
 #endif
 
         /* All seems OK, enable tracing */
-        global_trace.ctrl = tracer_enabled;
+        global_trace.ctrl = 1;
         tracing_disabled = 0;
 
         atomic_notifier_chain_register(&panic_notifier_list,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index cc14a6bc1094..3422489fad5e 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -237,11 +237,11 @@ struct tracer {
         const char              *name;
         void                    (*init)(struct trace_array *tr);
         void                    (*reset)(struct trace_array *tr);
+        void                    (*start)(struct trace_array *tr);
+        void                    (*stop)(struct trace_array *tr);
         void                    (*open)(struct trace_iterator *iter);
         void                    (*pipe_open)(struct trace_iterator *iter);
         void                    (*close)(struct trace_iterator *iter);
-        void                    (*start)(struct trace_iterator *iter);
-        void                    (*stop)(struct trace_iterator *iter);
         ssize_t                 (*read)(struct trace_iterator *iter,
                                         struct file *filp, char __user *ubuf,
                                         size_t cnt, loff_t *ppos);
@@ -282,6 +282,7 @@ struct trace_iterator {
         long                    idx;
 };
 
+int tracing_is_enabled(void);
 void trace_wake_up(void);
 void tracing_reset(struct trace_array *tr, int cpu);
 int tracing_open_generic(struct inode *inode, struct file *filp);
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 0f85a64003d3..9f1b0de71284 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -62,11 +62,17 @@ static void function_trace_ctrl_update(struct trace_array *tr)
                 stop_function_trace(tr);
 }
 
+static void function_trace_start(struct trace_array *tr)
+{
+        function_reset(tr);
+}
+
 static struct tracer function_trace __read_mostly =
 {
         .name        = "function",
         .init        = function_trace_init,
         .reset       = function_trace_reset,
+        .start       = function_trace_start,
         .ctrl_update = function_trace_ctrl_update,
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest    = trace_selftest_startup_function,
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 9c74071c10e0..a87a20fa3fc6 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -353,15 +353,28 @@ void trace_preempt_off(unsigned long a0, unsigned long a1)
 }
 #endif /* CONFIG_PREEMPT_TRACER */
 
+/*
+ * save_tracer_enabled is used to save the state of the tracer_enabled
+ * variable when we disable it when we open a trace output file.
+ */
+static int save_tracer_enabled;
+
 static void start_irqsoff_tracer(struct trace_array *tr)
 {
         register_ftrace_function(&trace_ops);
-        tracer_enabled = 1;
+        if (tracing_is_enabled()) {
+                tracer_enabled = 1;
+                save_tracer_enabled = 1;
+        } else {
+                tracer_enabled = 0;
+                save_tracer_enabled = 0;
+        }
 }
 
 static void stop_irqsoff_tracer(struct trace_array *tr)
 {
         tracer_enabled = 0;
+        save_tracer_enabled = 0;
         unregister_ftrace_function(&trace_ops);
 }
 
@@ -389,17 +402,29 @@ static void irqsoff_tracer_ctrl_update(struct trace_array *tr)
                 stop_irqsoff_tracer(tr);
 }
 
+static void irqsoff_tracer_start(struct trace_array *tr)
+{
+        irqsoff_tracer_reset(tr);
+        tracer_enabled = 1;
+        save_tracer_enabled = 1;
+}
+
+static void irqsoff_tracer_stop(struct trace_array *tr)
+{
+        tracer_enabled = 0;
+        save_tracer_enabled = 0;
+}
+
 static void irqsoff_tracer_open(struct trace_iterator *iter)
 {
         /* stop the trace while dumping */
-        if (iter->tr->ctrl)
-                stop_irqsoff_tracer(iter->tr);
+        tracer_enabled = 0;
 }
 
 static void irqsoff_tracer_close(struct trace_iterator *iter)
 {
-        if (iter->tr->ctrl)
-                start_irqsoff_tracer(iter->tr);
+        /* restart tracing */
+        tracer_enabled = save_tracer_enabled;
 }
 
 #ifdef CONFIG_IRQSOFF_TRACER
@@ -414,6 +439,8 @@ static struct tracer irqsoff_tracer __read_mostly =
         .name           = "irqsoff",
         .init           = irqsoff_tracer_init,
         .reset          = irqsoff_tracer_reset,
+        .start          = irqsoff_tracer_start,
+        .stop           = irqsoff_tracer_stop,
         .open           = irqsoff_tracer_open,
         .close          = irqsoff_tracer_close,
         .ctrl_update    = irqsoff_tracer_ctrl_update,
@@ -440,6 +467,8 @@ static struct tracer preemptoff_tracer __read_mostly =
         .name           = "preemptoff",
         .init           = preemptoff_tracer_init,
         .reset          = irqsoff_tracer_reset,
+        .start          = irqsoff_tracer_start,
+        .stop           = irqsoff_tracer_stop,
         .open           = irqsoff_tracer_open,
         .close          = irqsoff_tracer_close,
         .ctrl_update    = irqsoff_tracer_ctrl_update,
@@ -468,6 +497,8 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
         .name           = "preemptirqsoff",
         .init           = preemptirqsoff_tracer_init,
         .reset          = irqsoff_tracer_reset,
+        .start          = irqsoff_tracer_start,
+        .stop           = irqsoff_tracer_stop,
         .open           = irqsoff_tracer_open,
         .close          = irqsoff_tracer_close,
         .ctrl_update    = irqsoff_tracer_ctrl_update,
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 888944d3409d..91c699be8c87 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -186,11 +186,24 @@ static void sched_switch_trace_ctrl_update(struct trace_array *tr)
                 stop_sched_trace(tr);
 }
 
+static void sched_switch_trace_start(struct trace_array *tr)
+{
+        sched_switch_reset(tr);
+        tracing_start_sched_switch();
+}
+
+static void sched_switch_trace_stop(struct trace_array *tr)
+{
+        tracing_stop_sched_switch();
+}
+
 struct tracer sched_switch_trace __read_mostly =
 {
         .name           = "sched_switch",
         .init           = sched_switch_trace_init,
         .reset          = sched_switch_trace_reset,
+        .start          = sched_switch_trace_start,
+        .stop           = sched_switch_trace_stop,
         .ctrl_update    = sched_switch_trace_ctrl_update,
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest    = trace_selftest_startup_sched_switch,
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 7bc4abf6fca8..240577bc8ba5 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -262,6 +262,12 @@ out:
         atomic_dec(&wakeup_trace->data[cpu]->disabled);
 }
 
+/*
+ * save_tracer_enabled is used to save the state of the tracer_enabled
+ * variable when we disable it when we open a trace output file.
+ */
+static int save_tracer_enabled;
+
 static void start_wakeup_tracer(struct trace_array *tr)
 {
         int ret;
@@ -300,7 +306,13 @@ static void start_wakeup_tracer(struct trace_array *tr)
 
         register_ftrace_function(&trace_ops);
 
-        tracer_enabled = 1;
+        if (tracing_is_enabled()) {
+                tracer_enabled = 1;
+                save_tracer_enabled = 1;
+        } else {
+                tracer_enabled = 0;
+                save_tracer_enabled = 0;
+        }
 
         return;
 fail_deprobe_wake_new:
@@ -312,6 +324,7 @@ fail_deprobe:
 static void stop_wakeup_tracer(struct trace_array *tr)
 {
         tracer_enabled = 0;
+        save_tracer_enabled = 0;
         unregister_ftrace_function(&trace_ops);
         unregister_trace_sched_switch(probe_wakeup_sched_switch);
         unregister_trace_sched_wakeup_new(probe_wakeup);
@@ -343,18 +356,32 @@ static void wakeup_tracer_ctrl_update(struct trace_array *tr)
                 stop_wakeup_tracer(tr);
 }
 
+static void wakeup_tracer_start(struct trace_array *tr)
+{
+        wakeup_reset(tr);
+        tracer_enabled = 1;
+        save_tracer_enabled = 1;
+}
+
+static void wakeup_tracer_stop(struct trace_array *tr)
+{
+        tracer_enabled = 0;
+        save_tracer_enabled = 0;
+}
+
 static void wakeup_tracer_open(struct trace_iterator *iter)
 {
         /* stop the trace while dumping */
-        if (iter->tr->ctrl)
-                stop_wakeup_tracer(iter->tr);
+        tracer_enabled = 0;
 }
 
 static void wakeup_tracer_close(struct trace_iterator *iter)
 {
         /* forget about any processes we were recording */
-        if (iter->tr->ctrl)
-                start_wakeup_tracer(iter->tr);
+        if (save_tracer_enabled) {
+                wakeup_reset(iter->tr);
+                tracer_enabled = 1;
+        }
 }
 
 static struct tracer wakeup_tracer __read_mostly =
@@ -362,6 +389,8 @@ static struct tracer wakeup_tracer __read_mostly =
         .name           = "wakeup",
         .init           = wakeup_tracer_init,
         .reset          = wakeup_tracer_reset,
+        .start          = wakeup_tracer_start,
+        .stop           = wakeup_tracer_stop,
         .open           = wakeup_tracer_open,
         .close          = wakeup_tracer_close,
         .ctrl_update    = wakeup_tracer_ctrl_update,