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Message-ID: <20140116001116.GA27182@redhat.com>
Date: Thu, 16 Jan 2014 01:11:16 +0100
From: Veaceslav Falico <vfalico@...hat.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Tejun Heo <tj@...nel.org>, Greg KH <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [RFC] sysfs_rename_link() and its usage
On Wed, Jan 15, 2014 at 03:25:16PM -0800, Eric W. Biederman wrote:
>Tejun Heo <tj@...nel.org> writes:
>
>> Hey, Veaceslav, Eric.
Hi Tejun, Eric,
>>
>> On Tue, Jan 14, 2014 at 05:35:23PM -0800, Eric W. Biederman wrote:
>>> >>> >>This works like a charm. However, if I want to use (obviously, with the
>>> >>> >>symlink present):
>>> >>> >>
>>> >>> >>sysfs_rename_link(&(a->dev.kobj), &(b->dev.kobj), oldname, newname);
>>> >>> >
>>> >>> >You forgot the namespace option to this call, what kernel version are
>>> >>> >you using here?
>>> >>>
>>> >>> It's git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next ,
>>> >>> 3.13-rc6 with some networking patches on top of it.
>>
>> Does this work on 3.12? How about Greg's driver-core-next? Do you
>> have a minimal test case that I can use to reproduce the issue?
Sorry for the latency in responses, I'll update once I'll manage to test it
on those.
...snip...
>> Veaceslav, please confirm whether the issue is reproducible w/ v3.12.
>
>Anyway since a symlink living in a different namespace from it's target
>is just nonsense this (only compile tested) patch should fix the issue,
>and make sysfs_rename_link usable for people without a masters degree in
>sysfs again.
It's still there :-(. I've used your patch and added my small addition[1] to
test the sysfs_rename_link() (on top of net-next, 3.13-rc7), however the
issue is still there:
[ 79.038340] net bond0: renaming to bondbla
[ 79.038380] ------------[ cut here ]------------
[ 79.038411] WARNING: CPU: 1 PID: 5318 at fs/sysfs/dir.c:618
sysfs_find_dirent+0x84/0x110()
[ 79.038449] sysfs: ns invalid in 'bridge0' for 'lower_bond0'
...snip...
[ 79.038877] [<ffffffff810ae826>] warn_slowpath_fmt+0x46/0x50
[ 79.038903] [<ffffffff812ba890>] ? sysfs_get_dirent_ns+0x30/0x80
[ 79.038930] [<ffffffff812b97c4>] sysfs_find_dirent+0x84/0x110
[ 79.038957] [<ffffffff812ba89e>] sysfs_get_dirent_ns+0x3e/0x80
[ 79.038983] [<ffffffff812baf87>] sysfs_rename_link+0x57/0xe0
[ 79.039030] [<ffffffff81689e72>] netdev_adjacent_rename_links+0xa2/0x160
The current scheme (sysfs_remove_link() + sysfs_add_link()) works perfectly
well without any namespaces. I'll dig into it once I have some spare time,
it's not at all critical.
[1]: the patch (I've included your patch too, just in case):
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 67b180d..0c9377a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1825,9 +1825,8 @@ int device_rename(struct device *dev, const char *new_name)
}
if (dev->class) {
- error = sysfs_rename_link_ns(&dev->class->p->subsys.kobj,
- kobj, old_device_name,
- new_name, kobject_namespace(kobj));
+ error = sysfs_rename_link(&dev->class->p->subsys.kobj,
+ kobj, old_device_name, new_name);
if (error)
goto out;
}
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 3ae3f1b..651444a 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -194,12 +194,10 @@ EXPORT_SYMBOL_GPL(sysfs_remove_link);
* @targ: object we're pointing to.
* @old: previous name of the symlink.
* @new: new name of the symlink.
- * @new_ns: new namespace of the symlink.
- *
* A helper function for the common rename symlink idiom.
*/
-int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
- const char *old, const char *new, const void *new_ns)
+int sysfs_rename_link(struct kobject *kobj, struct kobject *targ,
+ const char *old, const char *new)
{
struct sysfs_dirent *parent_sd, *sd = NULL;
const void *old_ns = NULL;
@@ -224,13 +222,13 @@ int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
if (sd->s_symlink.target_sd->s_dir.kobj != targ)
goto out;
- result = sysfs_rename(sd, parent_sd, new, new_ns);
+ result = sysfs_rename(sd, parent_sd, new, kobject_namespace(targ));
out:
sysfs_put(sd);
return result;
}
-EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);
+EXPORT_SYMBOL_GPL(sysfs_rename_link);
static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
struct sysfs_dirent *target_sd, char *path)
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 6695040..093d992 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -213,9 +213,8 @@ int __must_check sysfs_create_link_nowarn(struct kobject *kobj,
const char *name);
void sysfs_remove_link(struct kobject *kobj, const char *name);
-int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
- const char *old_name, const char *new_name,
- const void *new_ns);
+int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
+ const char *old_name, const char *new_name);
void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
const char *name);
@@ -341,9 +340,8 @@ static inline void sysfs_remove_link(struct kobject *kobj, const char *name)
{
}
-static inline int sysfs_rename_link_ns(struct kobject *k, struct kobject *t,
- const char *old_name,
- const char *new_name, const void *ns)
+static inline int sysfs_rename_link(struct kobject *k, struct kobject *t,
+ const char *old_name, const char *new_name)
{
return 0;
}
@@ -455,12 +453,6 @@ static inline void sysfs_remove_file(struct kobject *kobj,
return sysfs_remove_file_ns(kobj, attr, NULL);
}
-static inline int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
- const char *old_name, const char *new_name)
-{
- return sysfs_rename_link_ns(kobj, target, old_name, new_name, NULL);
-}
-
static inline struct sysfs_dirent *
sysfs_get_dirent(struct sysfs_dirent *parent_sd, const unsigned char *name)
{
diff --git a/net/core/dev.c b/net/core/dev.c
index 9957557..5d24d8e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5005,19 +5005,20 @@ EXPORT_SYMBOL(netdev_upper_dev_unlink);
void netdev_adjacent_rename_links(struct net_device *dev, char *oldname)
{
struct netdev_adjacent *iter;
+ char old_linkname[IFNAMSIZ+7], new_linkname[IFNAMSIZ+7];
list_for_each_entry(iter, &dev->adj_list.upper, list) {
- netdev_adjacent_sysfs_del(iter->dev, oldname,
- &iter->dev->adj_list.lower);
- netdev_adjacent_sysfs_add(iter->dev, dev,
- &iter->dev->adj_list.lower);
+ sprintf(old_linkname, "lower_%s", oldname);
+ sprintf(new_linkname, "lower_%s", dev->name);
+ sysfs_rename_link(&(iter->dev->dev.kobj), &(dev->dev.kobj),
+ old_linkname, new_linkname);
}
list_for_each_entry(iter, &dev->adj_list.lower, list) {
- netdev_adjacent_sysfs_del(iter->dev, oldname,
- &iter->dev->adj_list.upper);
- netdev_adjacent_sysfs_add(iter->dev, dev,
- &iter->dev->adj_list.upper);
+ sprintf(old_linkname, "upper_%s", oldname);
+ sprintf(new_linkname, "upper_%s", dev->name);
+ sysfs_rename_link(&(iter->dev->dev.kobj), &(dev->dev.kobj),
+ old_linkname, new_linkname);
}
}
--
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