Re: [patch V2 06/45] genirq/proc: Switch to lock guards

Thomas Gleixner
2025-06-09T09:50:19Z

On Sun, Jun 08 2025 at 20:45, Zenghui Yu wrote:
> On 2025/4/29 14:54, Thomas Gleixner wrote:
>> - raw_spin_lock_irqsave(&desc->lock, flags);
>> - if (desc->affinity_hint)
>> - cpumask_copy(mask, desc->affinity_hint);
>> - raw_spin_unlock_irqrestore(&desc->lock, flags);
>> + scoped_guard(raw_spinlock_irq, &desc->lock) {
>
> Any reason it has been switched to a raw_spinlock_irq?

Yes. This code is always thread context and can never be invoked with
interrupts disabled. So there is zero reason to use irqsave().

> I've hit some random Oops with the backtrace looks like:
>
> Call trace:
> string+0x110/0x3b8 (P)
> vsnprintf+0x2f0/0xac8
> seq_printf+0x180/0x220
> show_interrupts+0x4e0/0x7e0
> seq_read_iter+0x350/0xd80
> proc_reg_read_iter+0x194/0x248
> vfs_read+0x5b0/0x940
> ksys_read+0xf0/0x1e8
> __arm64_sys_read+0x74/0xb0
> invoke_syscall+0x74/0x270
> el0_svc_common.constprop.0+0xb4/0x240
> do_el0_svc+0x48/0x68
> el0_svc+0x4c/0xe8
> el0t_64_sync_handler+0xc8/0xd0
> el0t_64_sync+0x1ac/0x1b0
>
> I haven't dig further. But it looks to me that this patch had introduced
> functional change and I'm planning to give the following diff a go on
> the same box.

That won't help at all because the actual crash is within show_interrupts()....

Thanks,

tglx