Patch "wifi: mac80211: fortify the spinlock against deadlock by interrupt" has been added to the 6.3-stable tree

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This is a note to let you know that I've just added the patch titled

    wifi: mac80211: fortify the spinlock against deadlock by interrupt

to the 6.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     wifi-mac80211-fortify-the-spinlock-against-deadlock-.patch
and it can be found in the queue-6.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 00b75722abf193d7179b1f3a4dabb389ac6173d7
Author: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
Date:   Tue Apr 25 18:40:08 2023 +0200

    wifi: mac80211: fortify the spinlock against deadlock by interrupt
    
    [ 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@xxxxxxxxxxxx/
    Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
    Cc: Gregory Greenman <gregory.greenman@xxxxxxxxx>
    Cc: Johannes Berg <johannes.berg@xxxxxxxxx>
    Link: https://lore.kernel.org/all/cdc80531-f25f-6f9d-b15f-25e16130b53a@xxxxxxxxxxxx/
    Cc: David S. Miller <davem@xxxxxxxxxxxxx>
    Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
    Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
    Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
    Cc: Leon Romanovsky <leon@xxxxxxxxxx>
    Cc: Alexander Wetzel <alexander@xxxxxxxxxxxxxx>
    Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
    Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxx>
    Reviewed-by: tag, or it goes automatically?
    Link: https://lore.kernel.org/r/20230425164005.25272-1-mirsad.todorovac@xxxxxxxxxxxx
    Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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 */



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