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authorYann Droneaud <ydroneaud@opteya.com>2015-06-30 14:57:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-30 19:44:56 -0700
commitede1bf0dcff2b07001c760992b1ca18fd0f419bc (patch)
tree924a682aa9fa0d076840edc178521d15abacfcf5 /fs/namespace.c
parent0e1cc95b4cc7293bb7b39175035e7f7e45c90977 (diff)
fs: use seq_open_private() for proc_mounts
A patchset to remove support for passing pre-allocated struct seq_file to seq_open(). Such feature is undocumented and prone to error. In particular, if seq_release() is used in release handler, it will kfree() a pointer which was not allocated by seq_open(). So this patchset drops support for pre-allocated struct seq_file: it's only of use in proc_namespace.c and can be easily replaced by using seq_open_private()/seq_release_private(). Additionally, it documents the use of file->private_data to hold pointer to struct seq_file by seq_open(). This patch (of 3): 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@zeniv.linux.org.uk> 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. Such behavior is only used by mounts_open_common(). In order to drop support for such uncommon feature, proc_mounts is converted to use seq_open_private(), which take care of allocating the proc_mounts structure, making it available through ->private in struct seq_file. Conversely, proc_mounts is converted to use seq_release_private(), in order to release the private structure allocated by seq_open_private(). Then, ->private is used directly instead of proc_mounts() macro to access to the proc_mounts structure. Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@opteya.com Signed-off-by: Yann Droneaud <ydroneaud@opteya.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 9c1c43d0d4f1..e99f1f4e00cd 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1226,7 +1226,7 @@ EXPORT_SYMBOL(replace_mount_options);
/* iterator; we want it to have access to namespace_sem, thus here... */
static void *m_start(struct seq_file *m, loff_t *pos)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
down_read(&namespace_sem);
if (p->cached_event == p->ns->event) {
@@ -1247,7 +1247,7 @@ static void *m_start(struct seq_file *m, loff_t *pos)
static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
p->cached_mount = seq_list_next(v, &p->ns->list, pos);
p->cached_index = *pos;
@@ -1261,7 +1261,7 @@ static void m_stop(struct seq_file *m, void *v)
static int m_show(struct seq_file *m, void *v)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
struct mount *r = list_entry(v, struct mount, mnt_list);
return p->show(m, &r->mnt);
}