4 files changed, 38 insertions, 6 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index af9042977c08..f7488f44d26b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -660,6 +660,10 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
                 return;
 
         WARN_ON_ONCE(!irqs_disabled());
+        if (!current_trace->use_max_tr) {
+                WARN_ON_ONCE(1);
+                return;
+        }
         arch_spin_lock(&ftrace_max_lock);
 
         tr->buffer = max_tr.buffer;
@@ -686,6 +690,11 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
                 return;
 
         WARN_ON_ONCE(!irqs_disabled());
+        if (!current_trace->use_max_tr) {
+                WARN_ON_ONCE(1);
+                return;
+        }
+
         arch_spin_lock(&ftrace_max_lock);
 
         ftrace_disable_cpu();
@@ -2801,6 +2810,9 @@ static int tracing_resize_ring_buffer(unsigned long size)
         if (ret < 0)
                 return ret;
 
+        if (!current_trace->use_max_tr)
+                goto out;
+
         ret = ring_buffer_resize(max_tr.buffer, size);
         if (ret < 0) {
                 int r;
@@ -2828,11 +2840,14 @@ static int tracing_resize_ring_buffer(unsigned long size)
                 return ret;
         }
 
+        max_tr.entries = size;
+ out:
         global_trace.entries = size;
 
         return ret;
 }
 
+
 /**
  * tracing_update_buffers - used by tracing facility to expand ring buffers
  *
@@ -2893,12 +2908,26 @@ static int tracing_set_tracer(const char *buf)
         trace_branch_disable();
         if (current_trace && current_trace->reset)
                 current_trace->reset(tr);
-
+        if (current_trace && current_trace->use_max_tr) {
+                /*
+                 * We don't free the ring buffer. instead, resize it because
+                 * The max_tr ring buffer has some state (e.g. ring->clock) and
+                 * we want preserve it.
+                 */
+                ring_buffer_resize(max_tr.buffer, 1);
+                max_tr.entries = 1;
+        }
         destroy_trace_option_files(topts);
 
         current_trace = t;
 
         topts = create_trace_option_files(current_trace);
+        if (current_trace->use_max_tr) {
+                ret = ring_buffer_resize(max_tr.buffer, global_trace.entries);
+                if (ret < 0)
+                        goto out;
+                max_tr.entries = global_trace.entries;
+        }
 
         if (t->init) {
                 ret = tracer_init(t, tr);
@@ -3480,7 +3509,6 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
         }
 
         tracing_start();
-        max_tr.entries = global_trace.entries;
         mutex_unlock(&trace_types_lock);
 
         return cnt;
@@ -4578,16 +4606,14 @@ __init static int tracer_alloc_buffers(void)
 
 
 #ifdef CONFIG_TRACER_MAX_TRACE
-        max_tr.buffer = ring_buffer_alloc(ring_buf_size,
-                                             TRACE_BUFFER_FLAGS);
+        max_tr.buffer = ring_buffer_alloc(1, TRACE_BUFFER_FLAGS);
         if (!max_tr.buffer) {
                 printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
                 WARN_ON(1);
                 ring_buffer_free(global_trace.buffer);
                 goto out_free_cpumask;
         }
-        max_tr.entries = ring_buffer_size(max_tr.buffer);
-        WARN_ON(max_tr.entries != global_trace.entries);
+        max_tr.entries = 1;
 #endif
 
         /* Allocate the first page for all buffers */
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7778f067fc8b..cb629b3b108c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -276,6 +276,7 @@ struct tracer {
         struct tracer           *next;
         int                     print_max;
         struct tracer_flags     *flags;
+        int                     use_max_tr;
 };
 
 
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 6fd486e0cef4..73a6b0601f2e 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -649,6 +649,7 @@ static struct tracer irqsoff_tracer __read_mostly =
 #endif
         .open           = irqsoff_trace_open,
         .close          = irqsoff_trace_close,
+        .use_max_tr     = 1,
 };
 # define register_irqsoff(trace) register_tracer(&trace)
 #else
@@ -681,6 +682,7 @@ static struct tracer preemptoff_tracer __read_mostly =
 #endif
         .open           = irqsoff_trace_open,
         .close          = irqsoff_trace_close,
+        .use_max_tr     = 1,
 };
 # define register_preemptoff(trace) register_tracer(&trace)
 #else
@@ -715,6 +717,7 @@ static struct tracer preemptirqsoff_tracer __read_mostly =
 #endif
         .open           = irqsoff_trace_open,
         .close          = irqsoff_trace_close,
+        .use_max_tr     = 1,
 };
 
 # define register_preemptirqsoff(trace) register_tracer(&trace)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index c9fd5bd02036..4086eae6e81b 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -382,6 +382,7 @@ static struct tracer wakeup_tracer __read_mostly =
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest    = trace_selftest_startup_wakeup,
 #endif
+        .use_max_tr     = 1,
 };
 
 static struct tracer wakeup_rt_tracer __read_mostly =
@@ -396,6 +397,7 @@ static struct tracer wakeup_rt_tracer __read_mostly =
 #ifdef CONFIG_FTRACE_SELFTEST
         .selftest    = trace_selftest_startup_wakeup,
 #endif
+        .use_max_tr     = 1,
 };
 
 __init static int init_wakeup_tracer(void)