X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=fs%2Fseq_file.c;h=ce9e39fd5dafc768c27b2ceaa4e69a02c3ed1e6e;hb=b54a0935b03888c8412aa5acbf873af9d753fbdd;hp=d8a0545ad7ea43c08eefa531ab58b59073e6c422;hpb=8ea3a7c0df05b2cb33e2d63aa1c964308724b1c4;p=firefly-linux-kernel-4.4.55.git

diff --git a/fs/seq_file.c b/fs/seq_file.c
index d8a0545ad7ea..ce9e39fd5daf 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -48,18 +48,21 @@ static void *seq_buf_alloc(unsigned long size)
  *	ERR_PTR(error).  In the end of sequence they return %NULL. ->show()
  *	returns 0 in case of success and negative number in case of error.
  *	Returning SEQ_SKIP means "discard this element and move on".
+ *	Note: seq_open() will allocate a struct seq_file and store its
+ *	pointer in @file->private_data. This pointer should not be modified.
  */
 int seq_open(struct file *file, const struct seq_operations *op)
 {
-	struct seq_file *p = file->private_data;
+	struct seq_file *p;
+
+	WARN_ON(file->private_data);
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	file->private_data = p;
 
-	if (!p) {
-		p = kmalloc(sizeof(*p), GFP_KERNEL);
-		if (!p)
-			return -ENOMEM;
-		file->private_data = p;
-	}
-	memset(p, 0, sizeof(*p));
 	mutex_init(&p->lock);
 	p->op = op;
 #ifdef CONFIG_USER_NS
@@ -552,6 +555,7 @@ int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
 
 	return res;
 }
+EXPORT_SYMBOL(seq_dentry);
 
 static void *single_start(struct seq_file *p, loff_t *pos)
 {