tracing: Miscellaneous fixes for trace_array ref counting

Some error paths did not handle ref counting properly, and some trace files need
ref counting.

Link: http://lkml.kernel.org/r/1374171524-11948-1-git-send-email-azl@google.com

Cc: stable@vger.kernel.org # 3.10
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Alexander Z Lam <azl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 37 insertions, 8 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7c3da7bca05b..7d9ceab42564 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3008,7 +3008,6 @@ static int tracing_release(struct inode *inode, struct file *file)
 
         iter = m->private;
         tr = iter->tr;
-        trace_array_put(tr);
 
         mutex_lock(&trace_types_lock);
 
@@ -3023,6 +3022,9 @@ static int tracing_release(struct inode *inode, struct file *file)
         if (!iter->snapshot)
                 /* reenable tracing if it was previously enabled */
                 tracing_start_tr(tr);
+
+        __trace_array_put(tr);
+
         mutex_unlock(&trace_types_lock);
 
         mutex_destroy(&iter->mutex);
@@ -3447,6 +3449,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
 static int tracing_trace_options_open(struct inode *inode, struct file *file)
 {
         struct trace_array *tr = inode->i_private;
+        int ret;
 
         if (tracing_disabled)
                 return -ENODEV;
@@ -3454,7 +3457,11 @@ static int tracing_trace_options_open(struct inode *inode, struct file *file)
         if (trace_array_get(tr) < 0)
                 return -ENODEV;
 
-        return single_open(file, tracing_trace_options_show, inode->i_private);
+        ret = single_open(file, tracing_trace_options_show, inode->i_private);
+        if (ret < 0)
+                trace_array_put(tr);
+
+        return ret;
 }
 
 static const struct file_operations tracing_iter_fops = {
@@ -3958,6 +3965,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
         if (!iter) {
                 ret = -ENOMEM;
+                __trace_array_put(tr);
                 goto out;
         }
 
@@ -4704,21 +4712,24 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
                         ret = PTR_ERR(iter);
         } else {
                 /* Writes still need the seq_file to hold the private data */
+                ret = -ENOMEM;
                 m = kzalloc(sizeof(*m), GFP_KERNEL);
                 if (!m)
-                        return -ENOMEM;
+                        goto out;
                 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
                 if (!iter) {
                         kfree(m);
-                        return -ENOMEM;
+                        goto out;
                 }
+                ret = 0;
+
                 iter->tr = tr;
                 iter->trace_buffer = &tc->tr->max_buffer;
                 iter->cpu_file = tc->cpu;
                 m->private = iter;
                 file->private_data = m;
         }
-
+out:
         if (ret < 0)
                 trace_array_put(tr);
 
@@ -5328,9 +5339,10 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
 }
 
 static const struct file_operations tracing_stats_fops = {
-        .open           = tracing_open_generic,
+        .open           = tracing_open_generic_tc,
         .read           = tracing_stats_read,
         .llseek         = generic_file_llseek,
+        .release        = tracing_release_generic_tc,
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 7d854290bf81..7a75cb22eab7 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1218,6 +1218,7 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 
 static int ftrace_event_avail_open(struct inode *inode, struct file *file);
 static int ftrace_event_set_open(struct inode *inode, struct file *file);
+static int ftrace_event_release(struct inode *inode, struct file *file);
 
 static const struct seq_operations show_event_seq_ops = {
         .start = t_start,
@@ -1245,7 +1246,7 @@ static const struct file_operations ftrace_set_event_fops = {
         .read = seq_read,
         .write = ftrace_event_write,
         .llseek = seq_lseek,
-        .release = seq_release,
+        .release = ftrace_event_release,
 };
 
 static const struct file_operations ftrace_enable_fops = {
@@ -1323,6 +1324,15 @@ ftrace_event_open(struct inode *inode, struct file *file,
         return ret;
 }
 
+static int ftrace_event_release(struct inode *inode, struct file *file)
+{
+        struct trace_array *tr = inode->i_private;
+
+        trace_array_put(tr);
+
+        return seq_release(inode, file);
+}
+
 static int
 ftrace_event_avail_open(struct inode *inode, struct file *file)
 {
@@ -1336,12 +1346,19 @@ ftrace_event_set_open(struct inode *inode, struct file *file)
 {
         const struct seq_operations *seq_ops = &show_set_event_seq_ops;
         struct trace_array *tr = inode->i_private;
+        int ret;
+
+        if (trace_array_get(tr) < 0)
+                return -ENODEV;
 
         if ((file->f_mode & FMODE_WRITE) &&
             (file->f_flags & O_TRUNC))
                 ftrace_clear_events(tr);
 
-        return ftrace_event_open(inode, file, seq_ops);
+        ret = ftrace_event_open(inode, file, seq_ops);
+        if (ret < 0)
+                trace_array_put(tr);
+        return ret;
 }
 
 static struct event_subsystem *