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From: Thomas Gleixner <tglx@linutronix.de>
To: Juri Lelli <juri.lelli@redhat.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	sassmann@redhat.com
Subject: Re: [RT] Question about i40e threaded irq
Date: Tue, 11 May 2021 09:46:51 +0200	[thread overview]
Message-ID: <875yzphfv8.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <YJofplWBz8dT7xiw@localhost.localdomain>

On Tue, May 11 2021 at 08:09, Juri Lelli wrote:
> My understanding is that rps_trigger_softirq() sneaked in while
> i40e_msix_clean_rings() threaded irq was running and, since the latter is
> using napi_schedule_irqoff(), the softnet_data poll_list got eventually
> corrupted.
>
> Now, doing s/napi_schedule_irqoff/napi_schedule/ in the i40e driver seem
> to cure the problem. I'm not sure that there isn't a more general
> solution, though. Is it expected that napi_schedule_irqoff users in RT
> know what they are doing or do we want/need to fix this in a more
> general way?

The straight forward fix it to map napi_schedule_irqoff() to
napi_schedule() on RT. Fixing this at the driver level is a whack-a-mole
game.

Thanks,

        tglx

  parent reply	other threads:[~2021-05-11  7:46 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11  6:09 Juri Lelli
2021-05-11  6:24 ` Stefan Assmann
2021-05-11  7:46 ` Thomas Gleixner [this message]
2021-05-12 21:43 ` [PATCH net-next] net: Treat __napi_schedule_irqoff() as __napi_schedule() on PREEMPT_RT Sebastian Andrzej Siewior
2021-05-12 22:28   ` Thomas Gleixner
2021-05-13  0:50     ` Steven Rostedt
2021-05-13 16:43       ` Steven Rostedt
2021-05-14 12:11         ` Thomas Gleixner
2021-05-14 18:56     ` Jakub Kicinski
2021-05-14 19:44       ` Alison Chaiken
2021-05-14 21:53         ` Thomas Gleixner
2021-05-14 20:16       ` Thomas Gleixner
2021-05-14 20:38         ` Jakub Kicinski
2021-05-13  5:12   ` Juri Lelli
2021-05-13 20:20   ` patchwork-bot+netdevbpf

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