Since patch described below, from v2.6.15-rc1, seq_open()
could use a struct seq_file already allocated by the
caller if the pointer to the structure is stored in
file->private_data before calling the function.
Commit 1abe77b0fc4b485927f1f798ae81a752677e1d05
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Nov 7 17:15:34 2005 -0500
[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.
As there's no more use for such feature, as it could
be easily replaced by calls to seq_open_private()
(see commit 39699037a5c9 ("[FS] seq_file: Introduce
the seq_open_private()")) and seq_release_private()
(see v2.6.0-test3), support for this uncommon feature
can be removed from seq_open().
Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@xxxxxxxxxx
Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
---
fs/seq_file.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/seq_file.c b/fs/seq_file.c
index c14f6a43beb5..a909f12dad4d 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -51,15 +51,16 @@ static void *seq_buf_alloc(unsigned long size)
*/
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
--
2.4.2
--
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