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Johannes Berg 11d0d83119 wifi: iwlwifi: mvm: increase session protection after CSA
In the spec, CSA is defined roughly as follows:
 - TBTT x:     beacon with CSA, count=n   (old channel)
 - TBTT x+1:   beacon with CSA, count=n-1 (old channel)
 - TBTT x+n-1: beacon with CSA, count=1   (old channel)
 "A Channel Switch Count field set to 1 indicates that the switch
  occurs immediately before the next TBTT.
 - TBTT x+n:   beacon without CSA         (new channel)

When we detect it, we currently schedule the CSA event to
be at 10 TUs before TBTT x+n-1, for a beacon interval, to
give us quiet time.

When this event *starts*, we currently notify mac80211
that the channel switch happened, which causes us to add
a session protection event to listen for the first beacon
(and enable TX etc. when that arrives).

We don't even ask for a notification when this event ends
so the code that handles that is effectively dead code.

The session protection duration is 3 beacon intervals,
scheduled at 10 TU before TBTT x+n-1. It will thus end
just before TBTT x+n+2.

Unfortunately, if the AP doesn't transmit or we miss just
the first two beacons on the new channel, then this will
cause us to disconnect. Or even just one, if the AP isn't
quite aligned with the TBTT after the switch.

However, listening to the _end_ of the time event isn't
what we want either, because we want all the new PHY and
other config that needs to come from mac80211 to start
early, so we have a head-start for the new channel, since
we're not going to use the old one anyway for this time.

So since we don't really have anything better to do at
this time, and this is relatively rare, just make the
session protection use 5x the beacon interval instead of
just 3x, so it's more likely we catch a beacon even if
the AP neglected to send it, or we just miss it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230830112059.a74176bac37c.I029a2ebcd1b5012327c728ffa1d33fac19cfdf4b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
History 2023-09-11 12:36:25 +02:00
arch bpf-next-for-netdev 2023-08-25 18:40:15 -07:00
block block-6.5-2023-08-19 2023-08-19 17:31:46 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: fix uninit-value in af_alg_free_resources 2023-08-18 18:30:09 +08:00
Documentation doc/netlink: Add delete operation to ovs_vport spec 2023-08-25 18:58:34 -07:00
drivers wifi: iwlwifi: mvm: increase session protection after CSA 2023-09-11 12:36:25 +02:00
fs NFS client fixes for Linux 6.5 2023-08-22 10:50:17 -07:00
include wifi: cfg80211: add ieee80211_fragment_element to public API 2023-09-11 12:32:16 +02:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring/parisc: Adjust pgoff in io_uring mmap() for parisc 2023-08-08 12:37:01 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf-next-for-netdev 2023-08-25 18:40:15 -07:00
lib bpf-next-for-netdev 2023-08-25 18:40:15 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-24 10:51:39 -07:00
net wifi: mac80211: fix channel switch link data 2023-09-11 12:33:55 +02:00
rust rust: macros: vtable: fix HAS_* redefinition (gen_const_name) 2023-08-09 21:15:07 +02:00
samples samples/bpf: Add note to README about the XDP utilities moved to xdp-tools 2023-08-24 08:43:50 -07:00
scripts Kbuild fixes for v6.5 (2nd) 2023-08-13 08:56:24 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-24 10:51:39 -07:00
sound ALSA: hda/realtek - Remodified 3k pull low procedure 2023-08-16 14:20:27 +02:00
tools tools: ynl-gen: fix uAPI generation after tempfile changes 2023-08-25 18:56:48 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-07-29 11:05:28 -04:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap mailmap: add entries for Simon Horman 2023-08-16 09:53:10 +01:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: pcs: xpcs: support to switch mode for Wangxun NICs 2023-08-25 07:42:58 +01:00
Makefile Linux 6.5-rc7 2023-08-20 15:02:52 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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 Restructured Text 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.