From: Lin Ma <linma@zju.edu.cn>
To: jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, richardcochran@gmail.com,
ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org,
john.fastabend@gmail.com
Cc: pmenzel@molgen.mpg.de, vinschen@redhat.com,
regressions@lists.linux.dev, stable@vger.kernel.org,
intel-wired-lan@lists.osuosl.org, Lin Ma <linma@zju.edu.cn>
Subject: [Intel-wired-lan] [PATCH] igb: revert rtnl_lock() that causes deadlock
Date: Tue, 7 Mar 2023 21:05:47 +0800 [thread overview]
Message-ID: <20230307130547.31446-1-linma@zju.edu.cn> (raw)
In-Reply-To: <301b585a.80249.186bbe6cc50.Coremail.linma@zju.edu.cn>
The commit 6faee3d4ee8b ("igb: Add lock to avoid data race") adds
rtnl_lock to eliminate a false data race shown below
(FREE from device detaching) | (USE from netdev core)
igb_remove | igb_ndo_get_vf_config
igb_disable_sriov | vf >= adapter->vfs_allocated_count?
kfree(adapter->vf_data) |
adapter->vfs_allocated_count = 0 |
| memcpy(... adapter->vf_data[vf]
The above race will never happen and the extra rtnl_lock causes deadlock
below
[ 141.420169] <TASK>
[ 141.420672] __schedule+0x2dd/0x840
[ 141.421427] schedule+0x50/0xc0
[ 141.422041] schedule_preempt_disabled+0x11/0x20
[ 141.422678] __mutex_lock.isra.13+0x431/0x6b0
[ 141.423324] unregister_netdev+0xe/0x20
[ 141.423578] igbvf_remove+0x45/0xe0 [igbvf]
[ 141.423791] pci_device_remove+0x36/0xb0
[ 141.423990] device_release_driver_internal+0xc1/0x160
[ 141.424270] pci_stop_bus_device+0x6d/0x90
[ 141.424507] pci_stop_and_remove_bus_device+0xe/0x20
[ 141.424789] pci_iov_remove_virtfn+0xba/0x120
[ 141.425452] sriov_disable+0x2f/0xf0
[ 141.425679] igb_disable_sriov+0x4e/0x100 [igb]
[ 141.426353] igb_remove+0xa0/0x130 [igb]
[ 141.426599] pci_device_remove+0x36/0xb0
[ 141.426796] device_release_driver_internal+0xc1/0x160
[ 141.427060] driver_detach+0x44/0x90
[ 141.427253] bus_remove_driver+0x55/0xe0
[ 141.427477] pci_unregister_driver+0x2a/0xa0
[ 141.428296] __x64_sys_delete_module+0x141/0x2b0
[ 141.429126] ? mntput_no_expire+0x4a/0x240
[ 141.429363] ? syscall_trace_enter.isra.19+0x126/0x1a0
[ 141.429653] do_syscall_64+0x5b/0x80
[ 141.429847] ? exit_to_user_mode_prepare+0x14d/0x1c0
[ 141.430109] ? syscall_exit_to_user_mode+0x12/0x30
[ 141.430849] ? do_syscall_64+0x67/0x80
[ 141.431083] ? syscall_exit_to_user_mode_prepare+0x183/0x1b0
[ 141.431770] ? syscall_exit_to_user_mode+0x12/0x30
[ 141.432482] ? do_syscall_64+0x67/0x80
[ 141.432714] ? exc_page_fault+0x64/0x140
[ 141.432911] entry_SYSCALL_64_after_hwframe+0x72/0xdc
Since the igb_disable_sriov() will call pci_disable_sriov() before
releasing any resources, the netdev core will synchronize the cleanup to
avoid any races. This patch removes the useless rtnl_(un)lock to guarantee
correctness.
CC: stable@vger.kernel.org
Fixes: 6faee3d4ee8b ("igb: Add lock to avoid data race")
Reported-by: Corinna <vinschen@redhat.com>
Link: https://lore.kernel.org/regressions/3ef31c0b-ce40-20d0-7740-5dc0cca278ca@molgen.mpg.de/
Signed-off-by: Lin Ma <linma@zju.edu.cn>
---
drivers/net/ethernet/intel/igb/igb_main.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 03bc1e8af575..5532361b0e94 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3863,9 +3863,7 @@ static void igb_remove(struct pci_dev *pdev)
igb_release_hw_control(adapter);
#ifdef CONFIG_PCI_IOV
- rtnl_lock();
igb_disable_sriov(pdev);
- rtnl_unlock();
#endif
unregister_netdev(netdev);
--
2.34.1
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next prev parent reply other threads:[~2023-03-07 13:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-07 9:54 [Intel-wired-lan] Deadlock since commit 6faee3d4ee8b ("igb: Add lock to avoid data race") Corinna Vinschen
2023-03-07 10:12 ` [Intel-wired-lan] [REGRESSION] " Paul Menzel
2023-03-07 10:19 ` Paul Menzel
2023-03-07 10:36 ` Lin Ma
2023-03-07 12:11 ` Corinna Vinschen
2023-03-07 12:37 ` Lin Ma
2023-03-07 12:55 ` Corinna Vinschen
2023-03-07 11:48 ` Lin Ma
2023-03-07 13:05 ` Lin Ma [this message]
2023-03-07 13:17 ` [Intel-wired-lan] [PATCH] igb: revert rtnl_lock() that causes deadlock Linux regression tracking (Thorsten Leemhuis)
2023-03-07 13:45 ` Corinna Vinschen
2023-03-07 15:29 ` [Intel-wired-lan] [PATCH v2] " Lin Ma
2023-03-07 16:27 ` Corinna Vinschen
2023-03-07 23:22 ` Jacob Keller
2023-03-08 12:04 ` Simon Horman
2023-03-16 9:10 ` Romanowski, Rafal
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