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From: Thomas Gleixner <tglx@linutronix.de>
To: Christoph Hellwig <hch@infradead.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH REPOST] irq_poll: Add local_bh_disable() in cpu_dead notifier
Date: Sun, 10 Apr 2022 14:44:04 +0200	[thread overview]
Message-ID: <87o819glbf.ffs@tglx> (raw)
In-Reply-To: <YgYDePJLsVLXKqEP@infradead.org>

On Thu, Feb 10 2022 at 22:34, Christoph Hellwig wrote:
> On Thu, Feb 10, 2022 at 01:33:39PM +0100, Sebastian Andrzej Siewior wrote:
>> You need to handle the pending softirqs. If you don't handle them
>> immediately or in a deterministic say (like on IRQ exit) then they will
>> be handled at a random point.
>
> Yes.  Just like regular interrupts.

But interrupts make sure they are handled. This code does not and as
Sebastian pointed out:

  "If you don't handle them at all, the CPU will go idle and at least
   the NO_HZ will complain about pending softirqs (can_stop_idle_tick())."

That's clearly a bug, but this should be part of the changelog.

Thanks,

        tglx


  parent reply	other threads:[~2022-04-10 12:44 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-08 14:34 [PATCH REPOST] irq_poll: Add local_bh_disable() in cpu_dead notifier Sebastian Andrzej Siewior
2022-02-09  7:56 ` Christoph Hellwig
2022-02-10 12:33   ` Sebastian Andrzej Siewior
2022-02-11  6:34     ` Christoph Hellwig
2022-02-11 15:09       ` Sebastian Andrzej Siewior
2022-04-10 12:44       ` Thomas Gleixner [this message]
2022-04-10 12:49         ` [PATCH V2] lib/irq_poll: Add local_bh_disable() in irq_poll_cpu_dead() Thomas Gleixner
2022-04-13 19:38           ` [tip: core/core] lib/irq_poll: Prevent softirq pending leak " tip-bot2 for Sebastian Andrzej Siewior

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