mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 02:39:48 +00:00
![Randy Dunlap](/assets/img/avatar_default.png)
Correct spelling problems for Documentation/networking/ as reported by codespell. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: Jiri Pirko <jiri@nvidia.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Paolo Abeni <pabeni@redhat.com> Cc: netdev@vger.kernel.org Link: https://lore.kernel.org/r/20230129231053.20863-5-rdunlap@infradead.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
48 lines
1.9 KiB
ReStructuredText
48 lines
1.9 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
=============
|
|
Sysfs tagging
|
|
=============
|
|
|
|
(Taken almost verbatim from Eric Biederman's netns tagging patch
|
|
commit msg)
|
|
|
|
The problem. Network devices show up in sysfs and with the network
|
|
namespace active multiple devices with the same name can show up in
|
|
the same directory, ouch!
|
|
|
|
To avoid that problem and allow existing applications in network
|
|
namespaces to see the same interface that is currently presented in
|
|
sysfs, sysfs now has tagging directory support.
|
|
|
|
By using the network namespace pointers as tags to separate out
|
|
the sysfs directory entries we ensure that we don't have conflicts
|
|
in the directories and applications only see a limited set of
|
|
the network devices.
|
|
|
|
Each sysfs directory entry may be tagged with a namespace via the
|
|
``void *ns member`` of its ``kernfs_node``. If a directory entry is tagged,
|
|
then ``kernfs_node->flags`` will have a flag between KOBJ_NS_TYPE_NONE
|
|
and KOBJ_NS_TYPES, and ns will point to the namespace to which it
|
|
belongs.
|
|
|
|
Each sysfs superblock's kernfs_super_info contains an array
|
|
``void *ns[KOBJ_NS_TYPES]``. When a task in a tagging namespace
|
|
kobj_nstype first mounts sysfs, a new superblock is created. It
|
|
will be differentiated from other sysfs mounts by having its
|
|
``s_fs_info->ns[kobj_nstype]`` set to the new namespace. Note that
|
|
through bind mounting and mounts propagation, a task can easily view
|
|
the contents of other namespaces' sysfs mounts. Therefore, when a
|
|
namespace exits, it will call kobj_ns_exit() to invalidate any
|
|
kernfs_node->ns pointers pointing to it.
|
|
|
|
Users of this interface:
|
|
|
|
- define a type in the ``kobj_ns_type`` enumeration.
|
|
- call kobj_ns_type_register() with its ``kobj_ns_type_operations`` which has
|
|
|
|
- current_ns() which returns current's namespace
|
|
- netlink_ns() which returns a socket's namespace
|
|
- initial_ns() which returns the initial namespace
|
|
|
|
- call kobj_ns_exit() when an individual tag is no longer valid
|