mirror of
https://github.com/torvalds/linux.git
synced 2026-07-28 10:09:10 +02:00
Linux kernel source tree
346b3416fd
Kuniyuki Iwashima says:
====================
gtp/geneve: Suppress list_del() splat during ->exit_batch_rtnl().
The common pattern in tunnel device's ->exit_batch_rtnl() is iterating
two netdev lists for each netns: (i) for_each_netdev() to clean up
devices in the netns, and (ii) the device type specific list to clean
up devices in other netns.
list_for_each_entry(net, net_list, exit_list) {
for_each_netdev_safe(net, dev, next) {
/* (i) call unregister_netdevice_queue(dev, list) */
}
list_for_each_entry_safe(xxx, xxx_next, &net->yyy, zzz) {
/* (ii) call unregister_netdevice_queue(xxx->dev, list) */
}
}
Then, ->exit_batch_rtnl() could touch the same device twice.
Say we have two netns A & B and device B that is created in netns A and
moved to netns B.
1. cleanup_net() processes netns A and then B.
2. ->exit_batch_rtnl() finds the device B while iterating netns A's (ii)
[ device B is not yet unlinked from netns B as
unregister_netdevice_many() has not been called. ]
3. ->exit_batch_rtnl() finds the device B while iterating netns B's (i)
gtp and geneve calls ->dellink() at 2. and 3. that calls list_del() for (ii)
and unregister_netdevice_queue().
Calling unregister_netdevice_queue() twice is fine because it uses
list_move_tail(), but the 2nd list_del() triggers a splat when
CONFIG_DEBUG_LIST is enabled.
Possible solution is either of
(a) Use list_del_init() in ->dellink()
(b) Iterate dev with empty ->unreg_list for (i) like
#define for_each_netdev_alive(net, d) \
list_for_each_entry(d, &(net)->dev_base_head, dev_list) \
if (list_empty(&d->unreg_list))
(c) Remove (i) and delegate it to default_device_exit_batch().
This series avoids the 2nd ->dellink() by (c) to suppress the splat for
gtp and geneve.
Note that IPv4/IPv6 tunnels calls just unregister_netdevice() during
->exit_batch_rtnl() and dev is unlinked from (ii) later in ->ndo_uninit(),
so they are safe.
Also, pfcp has the same pattern but is safe because
unregister_netdevice_many() is called for each netns.
====================
Link: https://patch.msgid.link/20250217203705.40342-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.