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

[Zenghui Yu]

Hi Thomas,

On 2025/4/29 14:54, Thomas Gleixner wrote:
> Convert all lock/unlock pairs to guards and tidy up the code.
> 
> No functional change.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> 
> ---
>  kernel/irq/proc.c |   65 +++++++++++++++++++-----------------------------------
>  1 file changed, 24 insertions(+), 41 deletions(-)
> 
> --- a/kernel/irq/proc.c
> +++ b/kernel/irq/proc.c
> @@ -81,20 +81,18 @@ static int show_irq_affinity(int type, s
>  static int irq_affinity_hint_proc_show(struct seq_file *m, void *v)
>  {
>  	struct irq_desc *desc = irq_to_desc((long)m->private);
> -	unsigned long flags;
>  	cpumask_var_t mask;
>  
>  	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
>  		return -ENOMEM;
>  
> -	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?

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.

Thanks,
Zenghui