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171 lines
6.3 KiB
Diff
171 lines
6.3 KiB
Diff
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From fe2b1226656afae56702d1d84c6900f6b67df297 Mon Sep 17 00:00:00 2001
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From: Heiner Kallweit <hkallweit1@gmail.com>
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Date: Fri, 1 Dec 2023 11:23:22 +0100
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Subject: [PATCH] leds: trigger: netdev: fix RTNL handling to prevent potential
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deadlock
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When working on LED support for r8169 I got the following lockdep
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warning. Easiest way to prevent this scenario seems to be to take
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the RTNL lock before the trigger_data lock in set_device_name().
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======================================================
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WARNING: possible circular locking dependency detected
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6.7.0-rc2-next-20231124+ #2 Not tainted
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------------------------------------------------------
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bash/383 is trying to acquire lock:
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ffff888103aa1c68 (&trigger_data->lock){+.+.}-{3:3}, at: netdev_trig_notify+0xec/0x190 [ledtrig_netdev]
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but task is already holding lock:
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ffffffff8cddf808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x12/0x20
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which lock already depends on the new lock.
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the existing dependency chain (in reverse order) is:
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-> #1 (rtnl_mutex){+.+.}-{3:3}:
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__mutex_lock+0x9b/0xb50
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mutex_lock_nested+0x16/0x20
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rtnl_lock+0x12/0x20
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set_device_name+0xa9/0x120 [ledtrig_netdev]
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netdev_trig_activate+0x1a1/0x230 [ledtrig_netdev]
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led_trigger_set+0x172/0x2c0
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led_trigger_write+0xf1/0x140
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sysfs_kf_bin_write+0x5d/0x80
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kernfs_fop_write_iter+0x15d/0x210
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vfs_write+0x1f0/0x510
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ksys_write+0x6c/0xf0
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__x64_sys_write+0x14/0x20
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do_syscall_64+0x3f/0xf0
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entry_SYSCALL_64_after_hwframe+0x6c/0x74
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-> #0 (&trigger_data->lock){+.+.}-{3:3}:
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__lock_acquire+0x1459/0x25a0
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lock_acquire+0xc8/0x2d0
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__mutex_lock+0x9b/0xb50
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mutex_lock_nested+0x16/0x20
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netdev_trig_notify+0xec/0x190 [ledtrig_netdev]
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call_netdevice_register_net_notifiers+0x5a/0x100
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register_netdevice_notifier+0x85/0x120
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netdev_trig_activate+0x1d4/0x230 [ledtrig_netdev]
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led_trigger_set+0x172/0x2c0
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led_trigger_write+0xf1/0x140
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sysfs_kf_bin_write+0x5d/0x80
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kernfs_fop_write_iter+0x15d/0x210
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vfs_write+0x1f0/0x510
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ksys_write+0x6c/0xf0
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__x64_sys_write+0x14/0x20
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do_syscall_64+0x3f/0xf0
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entry_SYSCALL_64_after_hwframe+0x6c/0x74
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other info that might help us debug this:
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Possible unsafe locking scenario:
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CPU0 CPU1
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---- ----
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lock(rtnl_mutex);
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lock(&trigger_data->lock);
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lock(rtnl_mutex);
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lock(&trigger_data->lock);
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*** DEADLOCK ***
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8 locks held by bash/383:
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#0: ffff888103ff33f0 (sb_writers#3){.+.+}-{0:0}, at: ksys_write+0x6c/0xf0
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#1: ffff888103aa1e88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x114/0x210
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#2: ffff8881036f1890 (kn->active#82){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x11d/0x210
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#3: ffff888108e2c358 (&led_cdev->led_access){+.+.}-{3:3}, at: led_trigger_write+0x30/0x140
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#4: ffffffff8cdd9e10 (triggers_list_lock){++++}-{3:3}, at: led_trigger_write+0x75/0x140
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#5: ffff888108e2c270 (&led_cdev->trigger_lock){++++}-{3:3}, at: led_trigger_write+0xe3/0x140
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#6: ffffffff8cdde3d0 (pernet_ops_rwsem){++++}-{3:3}, at: register_netdevice_notifier+0x1c/0x120
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#7: ffffffff8cddf808 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x12/0x20
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stack backtrace:
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CPU: 0 PID: 383 Comm: bash Not tainted 6.7.0-rc2-next-20231124+ #2
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Hardware name: Default string Default string/Default string, BIOS ADLN.M6.SODIMM.ZB.CY.015 08/08/2023
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Call Trace:
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<TASK>
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dump_stack_lvl+0x5c/0xd0
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dump_stack+0x10/0x20
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print_circular_bug+0x2dd/0x410
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check_noncircular+0x131/0x150
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__lock_acquire+0x1459/0x25a0
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lock_acquire+0xc8/0x2d0
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? netdev_trig_notify+0xec/0x190 [ledtrig_netdev]
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__mutex_lock+0x9b/0xb50
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? netdev_trig_notify+0xec/0x190 [ledtrig_netdev]
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? __this_cpu_preempt_check+0x13/0x20
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? netdev_trig_notify+0xec/0x190 [ledtrig_netdev]
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? __cancel_work_timer+0x11c/0x1b0
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? __mutex_lock+0x123/0xb50
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mutex_lock_nested+0x16/0x20
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? mutex_lock_nested+0x16/0x20
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netdev_trig_notify+0xec/0x190 [ledtrig_netdev]
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call_netdevice_register_net_notifiers+0x5a/0x100
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register_netdevice_notifier+0x85/0x120
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netdev_trig_activate+0x1d4/0x230 [ledtrig_netdev]
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led_trigger_set+0x172/0x2c0
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? preempt_count_add+0x49/0xc0
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led_trigger_write+0xf1/0x140
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sysfs_kf_bin_write+0x5d/0x80
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kernfs_fop_write_iter+0x15d/0x210
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vfs_write+0x1f0/0x510
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ksys_write+0x6c/0xf0
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__x64_sys_write+0x14/0x20
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do_syscall_64+0x3f/0xf0
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entry_SYSCALL_64_after_hwframe+0x6c/0x74
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RIP: 0033:0x7f269055d034
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Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 80 3d 35 c3 0d 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 48 83 ec 28 48 89 54 24 18 48
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RSP: 002b:00007ffddb7ef748 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
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RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 00007f269055d034
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RDX: 0000000000000007 RSI: 000055bf5f4af3c0 RDI: 0000000000000001
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RBP: 000055bf5f4af3c0 R08: 0000000000000073 R09: 0000000000000001
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R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000007
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R13: 00007f26906325c0 R14: 00007f269062ff20 R15: 0000000000000000
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</TASK>
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Fixes: d5e01266e7f5 ("leds: trigger: netdev: add additional specific link speed mode")
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Cc: stable@vger.kernel.org
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Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
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Reviewed-by: Andrew Lunn <andrew@lunn.ch>
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Acked-by: Lee Jones <lee@kernel.org>
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Link: https://lore.kernel.org/r/fb5c8294-2a10-4bf5-8f10-3d2b77d2757e@gmail.com
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Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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---
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drivers/leds/trigger/ledtrig-netdev.c | 11 +++++++----
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1 file changed, 7 insertions(+), 4 deletions(-)
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--- a/drivers/leds/trigger/ledtrig-netdev.c
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+++ b/drivers/leds/trigger/ledtrig-netdev.c
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@@ -235,6 +235,11 @@ static int set_device_name(struct led_ne
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{
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cancel_delayed_work_sync(&trigger_data->work);
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+ /*
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+ * Take RTNL lock before trigger_data lock to prevent potential
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+ * deadlock with netdev notifier registration.
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+ */
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+ rtnl_lock();
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mutex_lock(&trigger_data->lock);
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if (trigger_data->net_dev) {
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@@ -254,16 +259,14 @@ static int set_device_name(struct led_ne
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trigger_data->carrier_link_up = false;
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trigger_data->link_speed = SPEED_UNKNOWN;
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trigger_data->duplex = DUPLEX_UNKNOWN;
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- if (trigger_data->net_dev != NULL) {
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- rtnl_lock();
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+ if (trigger_data->net_dev)
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get_device_state(trigger_data);
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- rtnl_unlock();
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- }
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trigger_data->last_activity = 0;
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set_baseline_state(trigger_data);
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mutex_unlock(&trigger_data->lock);
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+ rtnl_unlock();
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return 0;
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}
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