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Message-ID: <20200609163446.efp76qbjzkbtl7nk@linutronix.de>
Date: Tue, 9 Jun 2020 18:34:46 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Tom Zanussi <zanussi@...nel.org>
Cc: Ramon Fried <rfried.dev@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
linux-rt-users <linux-rt-users@...r.kernel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
Carsten Emde <C.Emde@...dl.org>,
John Kacur <jkacur@...hat.com>, Daniel Wagner <wagi@...om.org>,
Clark Williams <williams@...hat.com>,
Zhang Xiao <xiao.zhang@...driver.com>
Subject: Re: [PATCH RT 1/2] tasklet: Address a race resulting in
double-enqueue
On 2020-06-09 11:17:53 [-0500], Tom Zanussi wrote:
> Hi Sebastian,
Hi Tom,
> I did find a problem with the patch when configured as !SMP since in
> that case the RUN flag is never set (will send a patch for that
> shortly), but that wouldn't be the case here.
How?
| #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT_FULL)
| static inline int tasklet_trylock(struct tasklet_struct *t)
| {
| return !test_and_set_bit(TASKLET_STATE_RUN, &(t)->state);
| }
I can't tell from the backtrace if he runs with RT or without but I
assumed RT. But yes, for !SMP && !RT it would explain it.
> It would help to be able to reproduce it, but I haven't been able to
> yet.
>
> Tom
>
Sebastian
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