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Carolina Jubran fef965764c net/mlx5e: Prevent deadlock while disabling aRFS
When disabling aRFS under the `priv->state_lock`, any scheduled
aRFS works are canceled using the `cancel_work_sync` function,
which waits for the work to end if it has already started.
However, while waiting for the work handler, the handler will
try to acquire the `state_lock` which is already acquired.

The worker acquires the lock to delete the rules if the state
is down, which is not the worker's responsibility since
disabling aRFS deletes the rules.

Add an aRFS state variable, which indicates whether the aRFS is
enabled and prevent adding rules when the aRFS is disabled.

Kernel log:

======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc4_net_next_mlx5_5483eb2 #1 Tainted: G          I
------------------------------------------------------
ethtool/386089 is trying to acquire lock:
ffff88810f21ce68 ((work_completion)(&rule->arfs_work)){+.+.}-{0:0}, at: __flush_work+0x74/0x4e0

but task is already holding lock:
ffff8884a1808cc0 (&priv->state_lock){+.+.}-{3:3}, at: mlx5e_ethtool_set_channels+0x53/0x200 [mlx5_core]

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&priv->state_lock){+.+.}-{3:3}:
       __mutex_lock+0x80/0xc90
       arfs_handle_work+0x4b/0x3b0 [mlx5_core]
       process_one_work+0x1dc/0x4a0
       worker_thread+0x1bf/0x3c0
       kthread+0xd7/0x100
       ret_from_fork+0x2d/0x50
       ret_from_fork_asm+0x11/0x20

-> #0 ((work_completion)(&rule->arfs_work)){+.+.}-{0:0}:
       __lock_acquire+0x17b4/0x2c80
       lock_acquire+0xd0/0x2b0
       __flush_work+0x7a/0x4e0
       __cancel_work_timer+0x131/0x1c0
       arfs_del_rules+0x143/0x1e0 [mlx5_core]
       mlx5e_arfs_disable+0x1b/0x30 [mlx5_core]
       mlx5e_ethtool_set_channels+0xcb/0x200 [mlx5_core]
       ethnl_set_channels+0x28f/0x3b0
       ethnl_default_set_doit+0xec/0x240
       genl_family_rcv_msg_doit+0xd0/0x120
       genl_rcv_msg+0x188/0x2c0
       netlink_rcv_skb+0x54/0x100
       genl_rcv+0x24/0x40
       netlink_unicast+0x1a1/0x270
       netlink_sendmsg+0x214/0x460
       __sock_sendmsg+0x38/0x60
       __sys_sendto+0x113/0x170
       __x64_sys_sendto+0x20/0x30
       do_syscall_64+0x40/0xe0
       entry_SYSCALL_64_after_hwframe+0x46/0x4e

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&priv->state_lock);
                               lock((work_completion)(&rule->arfs_work));
                               lock(&priv->state_lock);
  lock((work_completion)(&rule->arfs_work));

 *** DEADLOCK ***

3 locks held by ethtool/386089:
 #0: ffffffff82ea7210 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40
 #1: ffffffff82e94c88 (rtnl_mutex){+.+.}-{3:3}, at: ethnl_default_set_doit+0xd3/0x240
 #2: ffff8884a1808cc0 (&priv->state_lock){+.+.}-{3:3}, at: mlx5e_ethtool_set_channels+0x53/0x200 [mlx5_core]

stack backtrace:
CPU: 15 PID: 386089 Comm: ethtool Tainted: G          I        6.7.0-rc4_net_next_mlx5_5483eb2 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x60/0xa0
 check_noncircular+0x144/0x160
 __lock_acquire+0x17b4/0x2c80
 lock_acquire+0xd0/0x2b0
 ? __flush_work+0x74/0x4e0
 ? save_trace+0x3e/0x360
 ? __flush_work+0x74/0x4e0
 __flush_work+0x7a/0x4e0
 ? __flush_work+0x74/0x4e0
 ? __lock_acquire+0xa78/0x2c80
 ? lock_acquire+0xd0/0x2b0
 ? mark_held_locks+0x49/0x70
 __cancel_work_timer+0x131/0x1c0
 ? mark_held_locks+0x49/0x70
 arfs_del_rules+0x143/0x1e0 [mlx5_core]
 mlx5e_arfs_disable+0x1b/0x30 [mlx5_core]
 mlx5e_ethtool_set_channels+0xcb/0x200 [mlx5_core]
 ethnl_set_channels+0x28f/0x3b0
 ethnl_default_set_doit+0xec/0x240
 genl_family_rcv_msg_doit+0xd0/0x120
 genl_rcv_msg+0x188/0x2c0
 ? ethnl_ops_begin+0xb0/0xb0
 ? genl_family_rcv_msg_dumpit+0xf0/0xf0
 netlink_rcv_skb+0x54/0x100
 genl_rcv+0x24/0x40
 netlink_unicast+0x1a1/0x270
 netlink_sendmsg+0x214/0x460
 __sock_sendmsg+0x38/0x60
 __sys_sendto+0x113/0x170
 ? do_user_addr_fault+0x53f/0x8f0
 __x64_sys_sendto+0x20/0x30
 do_syscall_64+0x40/0xe0
 entry_SYSCALL_64_after_hwframe+0x46/0x4e
 </TASK>

Fixes: 45bf454ae8 ("net/mlx5e: Enabling aRFS mechanism")
Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20240411115444.374475-7-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
History 2024-04-12 19:13:53 -07:00
arch LoongArch fixes for v6.9-rc4 2024-04-11 11:30:42 -07:00
block block-6.9-20240405 2024-04-05 17:04:11 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression that broke iwd as well as a divide by 2024-03-25 10:48:23 -07:00
Documentation bcachefs fixes for v6.9-rc4 2024-04-11 11:24:55 -07:00
drivers net/mlx5e: Prevent deadlock while disabling aRFS 2024-04-12 19:13:53 -07:00
fs bcachefs fixes for v6.9-rc4 2024-04-11 11:24:55 -07:00
include netfilter pull request 24-04-11 2024-04-12 13:02:13 +01:00
init fs/proc: Skip bootloader comment if no embedded kernel parameters 2024-04-09 23:36:18 +09:00
io_uring io_uring/kbuf: hold io_buffer_list reference over mmap 2024-04-02 19:03:27 -06:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel kprobes: Fix possible use-after-free issue on kprobe registration 2024-04-10 23:35:51 +09:00
lib Including fixes from bluetooth. 2024-04-11 11:46:31 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-05 11:21:31 -07:00
net af_unix: Don't peek OOB data without MSG_OOB. 2024-04-12 19:05:49 -07:00
rust Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts hardening fixes for v6.9-rc4 2024-04-10 13:31:34 -07:00
security security: Place security_path_post_mknod() where the original IMA call was 2024-04-03 10:21:32 -07:00
sound ASoC: Fixes for v6.9 2024-04-05 08:48:12 +02:00
tools Turbostat version 2024.04.10 2024-04-10 13:13:27 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM Xen and pfncache changes for 6.9: 2024-03-11 10:42:55 -04:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap MAINTAINERS: change vmware.com addresses to broadcom.com 2024-04-05 11:21:31 -07:00
.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 Not a ton of stuff happening in the clk framework in this pull request. We got 2024-03-15 11:48:01 -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 Including fixes from bluetooth. 2024-04-11 11:46:31 -07:00
Makefile Linux 6.9-rc3 2024-04-07 13:22:46 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 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.