tracing: Miscellaneous fixes for trace_array ref counting

Remove debugfs directories for tracing instances during creation if an error occurs causing the trace_array for that instance to not be added to ftrace_trace_arrays. If the directory continues to exist after the error, it cannot be removed because the respective trace_array is not in ftrace_trace_arrays.

Cc Vaibhav Nagarnaik <[email protected]>

Cc David Sharp <[email protected]>

Cc Alexander Z Lam <[email protected]>

Signed-off-by Alexander Z Lam <[email protected]>

---
 kernel/trace/trace.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

kernel/trace/trace.c +3 -1

index ca2743b..4ea9967 100644
@@ -5985,8 +5985,10 @@ static int new_instance_create(const char *name)
 		goto out_free_tr;
 
 	ret = event_trace_add_tracer(tr->dir, tr);
-	if (ret)
+	if (ret) {
+		debugfs_remove_recursive(tr->dir);
 		goto out_free_tr;
+	}
 
 	init_tracer_debugfs(tr, tr->dir);
 

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

Cc Vaibhav Nagarnaik <[email protected]>

Cc David Sharp <[email protected]>

Cc Alexander Z Lam <[email protected]>

Signed-off-by Alexander Z Lam <[email protected]>

---
 kernel/trace/trace.c        | 34 +++++++++++++++++++++++-----------
 kernel/trace/trace_events.c | 21 +++++++++++++++++++--
 2 files changed, 42 insertions(+), 13 deletions(-)

kernel/trace/trace.c +9 -2

index 0cd500b..ca2743b 100644
@@ -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 = {

kernel/trace/trace.c +4 -3

 	}
 
 	/*

@@ -3968,13 +3975,13 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
 	iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
 	if (!iter->trace) {
 		ret = -ENOMEM;
-		goto fail;
+		goto fail_trace;
 	}
 	*iter->trace = *tr->current_trace;
 
 	if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
 		ret = -ENOMEM;
-		goto fail;
+		goto fail_trace;
 	}
 
 	/* trace pipe does not show start of buffer */

@@ -4001,9 +4008,10 @@ out:
 	mutex_unlock(&trace_types_lock);
 	return ret;
 
-fail:
+fail_trace:
 	kfree(iter->trace);
 	kfree(iter);
+fail_iter:
 	__trace_array_put(tr);
 	mutex_unlock(&trace_types_lock);
 	return ret;

kernel/trace/trace.c +2 -1

 		iter = kzalloc(sizeof(*iter), GFP_KERNEL);
 		if (!iter) {
 			kfree(m);
-			return -ENOMEM;
+			ret = -ENOMEM;
+			goto out;
 		}
 		iter->tr = tr;
 		iter->trace_buffer = &tc->tr->max_buffer;

kernel/trace/trace.c +2 -1

@@ -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

kernel/trace/trace_events.c +19 -2

index 7d85429..7a75cb2 100644
@@ -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 *