From: Yann Droneaud Date: Tue, 30 Jun 2015 21:57:33 +0000 (-0700) Subject: fs: allocate structure unconditionally in seq_open() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=189f9841de23a58ecb4b2602db8581512ff08ba4;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git fs: allocate structure unconditionally in seq_open() 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 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@opteya.com Signed-off-by: Yann Droneaud Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/seq_file.c b/fs/seq_file.c index 555f82155be8..5f163c6c821c 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