RE: [PATCH v2] softirq: add irq off checking for __raise_softirq_irqoff

[Jiafei Pan]

@Thomas Gleixner, any more comments for v2 patch? Can we merge it? Thanks.

Best Regards,
Jiafei.

> -----Original Message-----
> From: Jiafei Pan <Jiafei.Pan@xxxxxxx>
> Sent: Friday, August 14, 2020 12:55 PM
> To: peterz@xxxxxxxxxxxxx; mingo@xxxxxxxxxx; tglx@xxxxxxxxxxxxx;
> rostedt@xxxxxxxxxxx; romain.perier@xxxxxxxxx; will@xxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-rt-users@xxxxxxxxxxxxxxx; Jiafei Pan
> <jiafei.pan@xxxxxxx>; Leo Li <leoyang.li@xxxxxxx>; Vladimir Oltean
> <vladimir.oltean@xxxxxxx>; Jiafei Pan <jiafei.pan@xxxxxxx>
> Subject: [PATCH v2] softirq: add irq off checking for __raise_softirq_irqoff
> 
> __raise_softirq_irqoff() will update per-CPU mask of pending softirqs,
> it need to be called in irq disabled context in order to keep it atomic
> operation, otherwise it will be interrupted by hardware interrupt,
> and per-CPU softirqs pending mask will be corrupted, the result is
> there will be unexpected issue, for example hrtimer soft irq will
> be losed and soft hrtimer will never be expire and handled.
> 
> Enable CONFIG_PROVE_LOCKING to use lockdep_assert_irqs_disabled() to
> check hardirqs and softirqs status, and provide warning in irqs enabled
> context.
> 
> Signed-off-by: Jiafei Pan <Jiafei.Pan@xxxxxxx>
> ---
> Changes in v2:
> - use lockdep_assert_irqs_disabled()
> - removed extra comments
> - changed commit message
> 
>  kernel/softirq.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index bf88d7f62433..09229ad82209 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -481,6 +481,7 @@ void raise_softirq(unsigned int nr)
> 
>  void __raise_softirq_irqoff(unsigned int nr)
>  {
> +	lockdep_assert_irqs_disabled();
>  	trace_softirq_raise(nr);
>  	or_softirq_pending(1UL << nr);
>  }
> --
> 2.17.1