1 files changed, 65 insertions, 18 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 10d3f0871b48..9d076a1ffa0b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -193,6 +193,37 @@ static struct trace_array	global_trace;
 
 LIST_HEAD(ftrace_trace_arrays);
 
+int trace_array_get(struct trace_array *this_tr)
+{
+        struct trace_array *tr;
+        int ret = -ENODEV;
+
+        mutex_lock(&trace_types_lock);
+        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+                if (tr == this_tr) {
+                        tr->ref++;
+                        ret = 0;
+                        break;
+                }
+        }
+        mutex_unlock(&trace_types_lock);
+
+        return ret;
+}
+
+static void __trace_array_put(struct trace_array *this_tr)
+{
+        WARN_ON(!this_tr->ref);
+        this_tr->ref--;
+}
+
+void trace_array_put(struct trace_array *this_tr)
+{
+        mutex_lock(&trace_types_lock);
+        __trace_array_put(this_tr);
+        mutex_unlock(&trace_types_lock);
+}
+
 int filter_current_check_discard(struct ring_buffer *buffer,
                                  struct ftrace_event_call *call, void *rec,
                                  struct ring_buffer_event *event)
@@ -2768,10 +2799,9 @@ static const struct seq_operations tracer_seq_ops = {
 };
 
 static struct trace_iterator *
-__tracing_open(struct inode *inode, struct file *file, bool snapshot)
+__tracing_open(struct trace_array *tr, struct trace_cpu *tc,
+               struct inode *inode, struct file *file, bool snapshot)
 {
-        struct trace_cpu *tc = inode->i_private;
-        struct trace_array *tr = tc->tr;
         struct trace_iterator *iter;
         int cpu;
 
@@ -2850,8 +2880,6 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
                 tracing_iter_reset(iter, cpu);
         }
 
-        tr->ref++;
-
         mutex_unlock(&trace_types_lock);
 
         return iter;
@@ -2881,17 +2909,20 @@ static int tracing_release(struct inode *inode, struct file *file)
         struct trace_array *tr;
         int cpu;
 
-        if (!(file->f_mode & FMODE_READ))
+        /* Writes do not use seq_file, need to grab tr from inode */
+        if (!(file->f_mode & FMODE_READ)) {
+                struct trace_cpu *tc = inode->i_private;
+
+                trace_array_put(tc->tr);
                 return 0;
+        }
 
         iter = m->private;
         tr = iter->tr;
+        trace_array_put(tr);
 
         mutex_lock(&trace_types_lock);
 
-        WARN_ON(!tr->ref);
-        tr->ref--;
-
         for_each_tracing_cpu(cpu) {
                 if (iter->buffer_iter[cpu])
                         ring_buffer_read_finish(iter->buffer_iter[cpu]);
@@ -2910,20 +2941,23 @@ static int tracing_release(struct inode *inode, struct file *file)
         kfree(iter->trace);
         kfree(iter->buffer_iter);
         seq_release_private(inode, file);
+
         return 0;
 }
 
 static int tracing_open(struct inode *inode, struct file *file)
 {
+        struct trace_cpu *tc = inode->i_private;
+        struct trace_array *tr = tc->tr;
         struct trace_iterator *iter;
         int ret = 0;
 
+        if (trace_array_get(tr) < 0)
+                return -ENODEV;
+
         /* If this file was open for write, then erase contents */
         if ((file->f_mode & FMODE_WRITE) &&
             (file->f_flags & O_TRUNC)) {
-                struct trace_cpu *tc = inode->i_private;
-                struct trace_array *tr = tc->tr;
-
                 if (tc->cpu == RING_BUFFER_ALL_CPUS)
                         tracing_reset_online_cpus(&tr->trace_buffer);
                 else
@@ -2931,12 +2965,16 @@ static int tracing_open(struct inode *inode, struct file *file)
         }
 
         if (file->f_mode & FMODE_READ) {
-                iter = __tracing_open(inode, file, false);
+                iter = __tracing_open(tr, tc, inode, file, false);
                 if (IS_ERR(iter))
                         ret = PTR_ERR(iter);
                 else if (trace_flags & TRACE_ITER_LATENCY_FMT)
                         iter->iter_flags |= TRACE_FILE_LAT_FMT;
         }
+
+        if (ret < 0)
+                trace_array_put(tr);
+
         return ret;
 }
 
@@ -4512,12 +4550,16 @@ struct ftrace_buffer_info {
 static int tracing_snapshot_open(struct inode *inode, struct file *file)
 {
         struct trace_cpu *tc = inode->i_private;
+        struct trace_array *tr = tc->tr;
         struct trace_iterator *iter;
         struct seq_file *m;
         int ret = 0;
 
+        if (trace_array_get(tr) < 0)
+                return -ENODEV;
+
         if (file->f_mode & FMODE_READ) {
-                iter = __tracing_open(inode, file, true);
+                iter = __tracing_open(tr, tc, inode, file, true);
                 if (IS_ERR(iter))
                         ret = PTR_ERR(iter);
         } else {
@@ -4530,13 +4572,16 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
                         kfree(m);
                         return -ENOMEM;
                 }
-                iter->tr = tc->tr;
+                iter->tr = tr;
                 iter->trace_buffer = &tc->tr->max_buffer;
                 iter->cpu_file = tc->cpu;
                 m->private = iter;
                 file->private_data = m;
         }
 
+        if (ret < 0)
+                trace_array_put(tr);
+
         return ret;
 }
 
@@ -4617,9 +4662,12 @@ out:
 static int tracing_snapshot_release(struct inode *inode, struct file *file)
 {
         struct seq_file *m = file->private_data;
+        int ret;
+
+        ret = tracing_release(inode, file);
 
         if (file->f_mode & FMODE_READ)
-                return tracing_release(inode, file);
+                return ret;
 
         /* If write only, the seq_file is just a stub */
         if (m)
@@ -4864,8 +4912,7 @@ static int tracing_buffers_release(struct inode *inode, struct file *file)
 
         mutex_lock(&trace_types_lock);
 
-        WARN_ON(!iter->tr->ref);
-        iter->tr->ref--;
+        __trace_array_put(iter->tr);
 
         if (info->spare)
                 ring_buffer_free_read_page(iter->trace_buffer->buffer, info->spare);