linux-kernel - RE: [PATCH v2] softirq: add irq off checking for __raise_softirq

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Date:   Thu, 10 Sep 2020 02:30:49 +0000
From:   Jiafei Pan <jiafei.pan@....com>
To:     Jiafei Pan <jiafei.pan@....com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "romain.perier@...il.com" <romain.perier@...il.com>,
        "will@...nel.org" <will@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-rt-users@...r.kernel.org" <linux-rt-users@...r.kernel.org>,
        Leo Li <leoyang.li@....com>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Jiafei Pan <jiafei.pan@....com>
Subject: RE: [PATCH v2] softirq: add irq off checking for
 __raise_softirq_irqoff

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

Best Regards,
Jiafei.

> -----Original Message-----
> From: Jiafei Pan <Jiafei.Pan@....com>
> Sent: Friday, August 14, 2020 12:55 PM
> To: peterz@...radead.org; mingo@...nel.org; tglx@...utronix.de;
> rostedt@...dmis.org; romain.perier@...il.com; will@...nel.org
> Cc: linux-kernel@...r.kernel.org; linux-rt-users@...r.kernel.org; Jiafei Pan
> <jiafei.pan@....com>; Leo Li <leoyang.li@....com>; Vladimir Oltean
> <vladimir.oltean@....com>; Jiafei Pan <jiafei.pan@....com>
> 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@....com>
> ---
> 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