[PATCH] allow callers of seq_open do allocation themselves

Allow caller of seq_open() to kmalloc() seq_file + whatever else they
want and set ->private_data to it.  seq_open() will then abstain from
doing allocation itself.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 38ef913767ff..7c40570b71dc 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -28,13 +28,17 @@
  */
 int seq_open(struct file *file, struct seq_operations *op)
 {
-        struct seq_file *p = kmalloc(sizeof(*p), GFP_KERNEL);
-        if (!p)
-                return -ENOMEM;
+        struct seq_file *p = file->private_data;
+
+        if (!p) {
+                p = kmalloc(sizeof(*p), GFP_KERNEL);
+                if (!p)
+                        return -ENOMEM;
+                file->private_data = p;
+        }
         memset(p, 0, sizeof(*p));
         sema_init(&p->sem, 1);
         p->op = op;
-        file->private_data = p;
 
         /*
          * Wrappers around seq_open(e.g. swaps_open) need to be