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Sven Eckelmann a7aa231728 batman-adv: Drop unmanaged ELP metric worker 
commit 8c8ecc98f5 upstream.

The ELP worker needs to calculate new metric values for all neighbors
"reachable" over an interface. Some of the used metric sources require
locks which might need to sleep. This sleep is incompatible with the RCU
list iterator used for the recorded neighbors. The initial approach to work
around of this problem was to queue another work item per neighbor and then
run this in a new context.

Even when this solved the RCU vs might_sleep() conflict, it has a major
problems: Nothing was stopping the work item in case it is not needed
anymore - for example because one of the related interfaces was removed or
the batman-adv module was unloaded - resulting in potential invalid memory
accesses.

Directly canceling the metric worker also has various problems:

* cancel_work_sync for a to-be-deactivated interface is called with
  rtnl_lock held. But the code in the ELP metric worker also tries to use
  rtnl_lock() - which will never return in this case. This also means that
  cancel_work_sync would never return because it is waiting for the worker
  to finish.
* iterating over the neighbor list for the to-be-deactivated interface is
  currently done using the RCU specific methods. Which means that it is
  possible to miss items when iterating over it without the associated
  spinlock - a behaviour which is acceptable for a periodic metric check
  but not for a cleanup routine (which must "stop" all still running
  workers)

The better approch is to get rid of the per interface neighbor metric
worker and handle everything in the interface worker. The original problems
are solved by:

* creating a list of neighbors which require new metric information inside
  the RCU protected context, gathering the metric according to the new list
  outside the RCU protected context
* only use rcu_trylock inside metric gathering code to avoid a deadlock
  when the cancel_delayed_work_sync is called in the interface removal code
  (which is called with the rtnl_lock held)

Cc: stable@vger.kernel.org
Fixes: c833484e5f ("batman-adv: ELP - compute the metric based on the estimated throughput")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-02-21 13:57:13 +01:00
arch x86/mm/tlb: Only trim the mm_cpumask once a second 2025-02-21 13:57:12 +01:00
block block: don't revert iter for -EIOCBQUEUED 2025-02-17 09:40:25 +01:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: ecc - Prevent ecc_digits_from_bytes from reading too many bytes 2025-01-09 13:31:52 +01:00
Documentation dt-bindings: mfd: bd71815: Fix rsense and typos 2025-02-08 09:51:52 +01:00
drivers ACPI: x86: Add skip i2c clients quirk for Vexia EDU ATLA 10 tablet 5V 2025-02-21 13:57:12 +01:00
fs orangefs: fix a oob in orangefs_debug_write 2025-02-21 13:57:12 +01:00
include block: cleanup and fix batch completion adding conditions 2025-02-21 13:57:09 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-09 10:32:46 +01:00
io_uring io_uring/rw: commit provided buffer state on async 2025-02-17 09:40:37 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-09 10:32:54 +01:00
kernel cgroup: Remove steal time from usage_usec 2025-02-21 13:57:08 +01:00
lib maple_tree: simplify split calculation 2025-02-17 09:40:39 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: kmemleak: fix upper boundary check for physical address objects 2025-02-17 09:40:35 +01:00
net batman-adv: Drop unmanaged ELP metric worker 2025-02-21 13:57:13 +01:00
rust rust: init: use explicit ABI to clean warning in future compilers 2025-02-17 09:40:27 +01:00
samples samples/landlock: Fix possible NULL dereference in parse_path() 2025-02-08 09:51:57 +01:00
scripts scripts/gdb: fix aarch64 userspace detection in get_current_task 2025-02-17 09:40:39 +01:00
security tomoyo: don't emit warning in tomoyo_write_control() 2025-02-17 09:40:07 +01:00
sound ASoC: Intel: bytcr_rt5640: Add DMI quirk for Vexia Edu Atla 10 tablet 5V 2025-02-21 13:57:12 +01:00
tools selftests: gpio: gpio-sim: Fix missing chip disablements 2025-02-21 13:57:12 +01:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock 2024-10-04 16:29:47 +02:00
.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 Remove *.orig pattern from .gitignore 2024-10-04 16:29:44 +02:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.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 USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
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 membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile tools: fix annoying "mkdir -p ..." logs when building tools in parallel 2025-02-21 13:57:09 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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 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.