Re: [PATCH] drop_monitor: replace spin_lock by raw_spin_lock

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by David S. Miller <davem@xxxxxxxxxxxxx>:

On Thu, 11 Apr 2024 11:13:46 -0300 you wrote:
> trace_drop_common() is called with preemption disabled, and it acquires
> a spin_lock. This is problematic for RT kernels because spin_locks are
> sleeping locks in this configuration, which causes the following splat:
> 
> BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
> in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 449, name: rcuc/47
> preempt_count: 1, expected: 0
> RCU nest depth: 2, expected: 2
> 5 locks held by rcuc/47/449:
>  #0: ff1100086ec30a60 ((softirq_ctrl.lock)){+.+.}-{2:2}, at: __local_bh_disable_ip+0x105/0x210
>  #1: ffffffffb394a280 (rcu_read_lock){....}-{1:2}, at: rt_spin_lock+0xbf/0x130
>  #2: ffffffffb394a280 (rcu_read_lock){....}-{1:2}, at: __local_bh_disable_ip+0x11c/0x210
>  #3: ffffffffb394a160 (rcu_callback){....}-{0:0}, at: rcu_do_batch+0x360/0xc70
>  #4: ff1100086ee07520 (&data->lock){+.+.}-{2:2}, at: trace_drop_common.constprop.0+0xb5/0x290
> irq event stamp: 139909
> hardirqs last  enabled at (139908): [<ffffffffb1df2b33>] _raw_spin_unlock_irqrestore+0x63/0x80
> hardirqs last disabled at (139909): [<ffffffffb19bd03d>] trace_drop_common.constprop.0+0x26d/0x290
> softirqs last  enabled at (139892): [<ffffffffb07a1083>] __local_bh_enable_ip+0x103/0x170
> softirqs last disabled at (139898): [<ffffffffb0909b33>] rcu_cpu_kthread+0x93/0x1f0
> Preemption disabled at:
> [<ffffffffb1de786b>] rt_mutex_slowunlock+0xab/0x2e0
> CPU: 47 PID: 449 Comm: rcuc/47 Not tainted 6.9.0-rc2-rt1+ #7
> Hardware name: Dell Inc. PowerEdge R650/0Y2G81, BIOS 1.6.5 04/15/2022
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x8c/0xd0
>  dump_stack+0x14/0x20
>  __might_resched+0x21e/0x2f0
>  rt_spin_lock+0x5e/0x130
>  ? trace_drop_common.constprop.0+0xb5/0x290
>  ? skb_queue_purge_reason.part.0+0x1bf/0x230
>  trace_drop_common.constprop.0+0xb5/0x290
>  ? preempt_count_sub+0x1c/0xd0
>  ? _raw_spin_unlock_irqrestore+0x4a/0x80
>  ? __pfx_trace_drop_common.constprop.0+0x10/0x10
>  ? rt_mutex_slowunlock+0x26a/0x2e0
>  ? skb_queue_purge_reason.part.0+0x1bf/0x230
>  ? __pfx_rt_mutex_slowunlock+0x10/0x10
>  ? skb_queue_purge_reason.part.0+0x1bf/0x230
>  trace_kfree_skb_hit+0x15/0x20
>  trace_kfree_skb+0xe9/0x150
>  kfree_skb_reason+0x7b/0x110
>  skb_queue_purge_reason.part.0+0x1bf/0x230
>  ? __pfx_skb_queue_purge_reason.part.0+0x10/0x10
>  ? mark_lock.part.0+0x8a/0x520
> ...
> 
> [...]

Here is the summary with links:
  - drop_monitor: replace spin_lock by raw_spin_lock
    https://git.kernel.org/netdev/net-next/c/f1e197a665c2

You are awesome, thank you!
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