linux-kernel - Re: [PATCH] softirq: Provide a handshake for canceling tasklets via polling on PREEMPT

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Message-ID: <aKNlshZmWsHVXBo0@slm.duckdns.org>
Date: Mon, 18 Aug 2025 07:41:06 -1000
From: Tejun Heo <tj@...nel.org>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] softirq: Provide a handshake for canceling tasklets via
 polling on PREEMPT_RT

Hello,

On Mon, Aug 18, 2025 at 02:52:42PM +0200, Sebastian Andrzej Siewior wrote:
...
> > Right, given how early in conversion, we can definitely leave this as
> > something to think about later. I have no objection to leave it be for now.
> 
> Okay. Do I need to update __flush_work() in anyway to make it obvious?
> The local_bh_disable()/ local_bh_enable() will become a nop in this
> regard and should be removed.
> It would be the revert of commit 134874e2eee93 ("workqueue: Allow
> cancel_work_sync() and disable_work() from atomic contexts on BH work
> items"). The commit added the possibility to flush BH work from atomic
> context but it is unclear if there already a requirement for this or if
> it was to match the legacy part of the tasklet API.

I see. Can I backtrack? If it doesn't require too invasive changes, let's
just keep the two in sync. I'll get back to conversions so that we can
actually achieve the goal eventually and it'll probably be more confusing if
we revert that and try to redo it later.

Thanks.

-- 
tejun