From: Mirsad Goran Todorovac mirsad.todorovac@alu.unizg.hr
[ Upstream commit ef6e1997da63ad0ac3fe33153fec9524c9ae56c9 ]
In the function ieee80211_tx_dequeue() there is a particular locking sequence:
begin: spin_lock(&local->queue_stop_reason_lock); q_stopped = local->queue_stop_reasons[q]; spin_unlock(&local->queue_stop_reason_lock);
However small the chance (increased by ftracetest), an asynchronous interrupt can occur in between of spin_lock() and spin_unlock(), and the interrupt routine will attempt to lock the same &local->queue_stop_reason_lock again.
This will cause a costly reset of the CPU and the wifi device or an altogether hang in the single CPU and single core scenario.
The only remaining spin_lock(&local->queue_stop_reason_lock) that did not disable interrupts was patched, which should prevent any deadlocks on the same CPU/core and the same wifi device.
This is the probable trace of the deadlock:
kernel: ================================ kernel: WARNING: inconsistent lock state kernel: 6.3.0-rc6-mt-20230401-00001-gf86822a1170f #4 Tainted: G W kernel: -------------------------------- kernel: inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. kernel: kworker/5:0/25656 [HC0[0]:SC0[0]:HE1:SE1] takes: kernel: ffff9d6190779478 (&local->queue_stop_reason_lock){+.?.}-{2:2}, at: return_to_handler+0x0/0x40 kernel: {IN-SOFTIRQ-W} state was registered at: kernel: lock_acquire+0xc7/0x2d0 kernel: _raw_spin_lock+0x36/0x50 kernel: ieee80211_tx_dequeue+0xb4/0x1330 [mac80211] kernel: iwl_mvm_mac_itxq_xmit+0xae/0x210 [iwlmvm] kernel: iwl_mvm_mac_wake_tx_queue+0x2d/0xd0 [iwlmvm] kernel: ieee80211_queue_skb+0x450/0x730 [mac80211] kernel: __ieee80211_xmit_fast.constprop.66+0x834/0xa50 [mac80211] kernel: __ieee80211_subif_start_xmit+0x217/0x530 [mac80211] kernel: ieee80211_subif_start_xmit+0x60/0x580 [mac80211] kernel: dev_hard_start_xmit+0xb5/0x260 kernel: __dev_queue_xmit+0xdbe/0x1200 kernel: neigh_resolve_output+0x166/0x260 kernel: ip_finish_output2+0x216/0xb80 kernel: __ip_finish_output+0x2a4/0x4d0 kernel: ip_finish_output+0x2d/0xd0 kernel: ip_output+0x82/0x2b0 kernel: ip_local_out+0xec/0x110 kernel: igmpv3_sendpack+0x5c/0x90 kernel: igmp_ifc_timer_expire+0x26e/0x4e0 kernel: call_timer_fn+0xa5/0x230 kernel: run_timer_softirq+0x27f/0x550 kernel: __do_softirq+0xb4/0x3a4 kernel: irq_exit_rcu+0x9b/0xc0 kernel: sysvec_apic_timer_interrupt+0x80/0xa0 kernel: asm_sysvec_apic_timer_interrupt+0x1f/0x30 kernel: _raw_spin_unlock_irqrestore+0x3f/0x70 kernel: free_to_partial_list+0x3d6/0x590 kernel: __slab_free+0x1b7/0x310 kernel: kmem_cache_free+0x52d/0x550 kernel: putname+0x5d/0x70 kernel: do_sys_openat2+0x1d7/0x310 kernel: do_sys_open+0x51/0x80 kernel: __x64_sys_openat+0x24/0x30 kernel: do_syscall_64+0x5c/0x90 kernel: entry_SYSCALL_64_after_hwframe+0x72/0xdc kernel: irq event stamp: 5120729 kernel: hardirqs last enabled at (5120729): [<ffffffff9d149936>] trace_graph_return+0xd6/0x120 kernel: hardirqs last disabled at (5120728): [<ffffffff9d149950>] trace_graph_return+0xf0/0x120 kernel: softirqs last enabled at (5069900): [<ffffffff9cf65b60>] return_to_handler+0x0/0x40 kernel: softirqs last disabled at (5067555): [<ffffffff9cf65b60>] return_to_handler+0x0/0x40 kernel: other info that might help us debug this: kernel: Possible unsafe locking scenario: kernel: CPU0 kernel: ---- kernel: lock(&local->queue_stop_reason_lock); kernel: <Interrupt> kernel: lock(&local->queue_stop_reason_lock); kernel: *** DEADLOCK *** kernel: 8 locks held by kworker/5:0/25656: kernel: #0: ffff9d618009d138 ((wq_completion)events_freezable){+.+.}-{0:0}, at: process_one_work+0x1ca/0x530 kernel: #1: ffffb1ef4637fe68 ((work_completion)(&local->restart_work)){+.+.}-{0:0}, at: process_one_work+0x1ce/0x530 kernel: #2: ffffffff9f166548 (rtnl_mutex){+.+.}-{3:3}, at: return_to_handler+0x0/0x40 kernel: #3: ffff9d6190778728 (&rdev->wiphy.mtx){+.+.}-{3:3}, at: return_to_handler+0x0/0x40 kernel: #4: ffff9d619077b480 (&mvm->mutex){+.+.}-{3:3}, at: return_to_handler+0x0/0x40 kernel: #5: ffff9d61907bacd8 (&trans_pcie->mutex){+.+.}-{3:3}, at: return_to_handler+0x0/0x40 kernel: #6: ffffffff9ef9cda0 (rcu_read_lock){....}-{1:2}, at: iwl_mvm_queue_state_change+0x59/0x3a0 [iwlmvm] kernel: #7: ffffffff9ef9cda0 (rcu_read_lock){....}-{1:2}, at: iwl_mvm_mac_itxq_xmit+0x42/0x210 [iwlmvm] kernel: stack backtrace: kernel: CPU: 5 PID: 25656 Comm: kworker/5:0 Tainted: G W 6.3.0-rc6-mt-20230401-00001-gf86822a1170f #4 kernel: Hardware name: LENOVO 82H8/LNVNB161216, BIOS GGCN51WW 11/16/2022 kernel: Workqueue: events_freezable ieee80211_restart_work [mac80211] kernel: Call Trace: kernel: <TASK> kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: dump_stack_lvl+0x5f/0xa0 kernel: dump_stack+0x14/0x20 kernel: print_usage_bug.part.46+0x208/0x2a0 kernel: mark_lock.part.47+0x605/0x630 kernel: ? sched_clock+0xd/0x20 kernel: ? trace_clock_local+0x14/0x30 kernel: ? __rb_reserve_next+0x5f/0x490 kernel: ? _raw_spin_lock+0x1b/0x50 kernel: __lock_acquire+0x464/0x1990 kernel: ? mark_held_locks+0x4e/0x80 kernel: lock_acquire+0xc7/0x2d0 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: ? ftrace_return_to_handler+0x8b/0x100 kernel: ? preempt_count_add+0x4/0x70 kernel: _raw_spin_lock+0x36/0x50 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: ieee80211_tx_dequeue+0xb4/0x1330 [mac80211] kernel: ? prepare_ftrace_return+0xc5/0x190 kernel: ? ftrace_graph_func+0x16/0x20 kernel: ? 0xffffffffc02ab0b1 kernel: ? lock_acquire+0xc7/0x2d0 kernel: ? iwl_mvm_mac_itxq_xmit+0x42/0x210 [iwlmvm] kernel: ? ieee80211_tx_dequeue+0x9/0x1330 [mac80211] kernel: ? __rcu_read_lock+0x4/0x40 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_mvm_mac_itxq_xmit+0xae/0x210 [iwlmvm] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_mvm_queue_state_change+0x311/0x3a0 [iwlmvm] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_mvm_wake_sw_queue+0x17/0x20 [iwlmvm] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_txq_gen2_unmap+0x1c9/0x1f0 [iwlwifi] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_txq_gen2_free+0x55/0x130 [iwlwifi] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_txq_gen2_tx_free+0x63/0x80 [iwlwifi] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: _iwl_trans_pcie_gen2_stop_device+0x3f3/0x5b0 [iwlwifi] kernel: ? _iwl_trans_pcie_gen2_stop_device+0x9/0x5b0 [iwlwifi] kernel: ? mutex_lock_nested+0x4/0x30 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_trans_pcie_gen2_stop_device+0x5f/0x90 [iwlwifi] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_mvm_stop_device+0x78/0xd0 [iwlmvm] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: __iwl_mvm_mac_start+0x114/0x210 [iwlmvm] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: iwl_mvm_mac_start+0x76/0x150 [iwlmvm] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: drv_start+0x79/0x180 [mac80211] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: ieee80211_reconfig+0x1523/0x1ce0 [mac80211] kernel: ? synchronize_net+0x4/0x50 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: ieee80211_restart_work+0x108/0x170 [mac80211] kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: process_one_work+0x250/0x530 kernel: ? ftrace_regs_caller_end+0x66/0x66 kernel: worker_thread+0x48/0x3a0 kernel: ? __pfx_worker_thread+0x10/0x10 kernel: kthread+0x10f/0x140 kernel: ? __pfx_kthread+0x10/0x10 kernel: ret_from_fork+0x29/0x50 kernel: </TASK>
Fixes: 4444bc2116ae ("wifi: mac80211: Proper mark iTXQs for resumption") Link: https://lore.kernel.org/all/1f58a0d1-d2b9-d851-73c3-93fcc607501c@alu.unizg.h... Reported-by: Mirsad Goran Todorovac mirsad.todorovac@alu.unizg.hr Cc: Gregory Greenman gregory.greenman@intel.com Cc: Johannes Berg johannes.berg@intel.com Link: https://lore.kernel.org/all/cdc80531-f25f-6f9d-b15f-25e16130b53a@alu.unizg.h... Cc: David S. Miller davem@davemloft.net Cc: Eric Dumazet edumazet@google.com Cc: Jakub Kicinski kuba@kernel.org Cc: Paolo Abeni pabeni@redhat.com Cc: Leon Romanovsky leon@kernel.org Cc: Alexander Wetzel alexander@wetzel-home.de Signed-off-by: Mirsad Goran Todorovac mirsad.todorovac@alu.unizg.hr Reviewed-by: Leon Romanovsky leonro@nvidia.com Reviewed-by: tag, or it goes automatically? Link: https://lore.kernel.org/r/20230425164005.25272-1-mirsad.todorovac@alu.unizg.... Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/mac80211/tx.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 7699fb4106701..45cb8e7bcc613 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -3781,6 +3781,7 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, ieee80211_tx_result r; struct ieee80211_vif *vif = txq->vif; int q = vif->hw_queue[txq->ac]; + unsigned long flags; bool q_stopped;
WARN_ON_ONCE(softirq_count() == 0); @@ -3789,9 +3790,9 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw, return NULL;
begin: - spin_lock(&local->queue_stop_reason_lock); + spin_lock_irqsave(&local->queue_stop_reason_lock, flags); q_stopped = local->queue_stop_reasons[q]; - spin_unlock(&local->queue_stop_reason_lock); + spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
if (unlikely(q_stopped)) { /* mark for waking later */