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Message-ID: <20220519145438.GJ2578@worktop.programming.kicks-ass.net>
Date: Thu, 19 May 2022 16:54:38 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Phil Auld <pauld@...hat.com>,
Alex Belits <abelits@...vell.com>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
Xiongfeng Wang <wangxiongfeng2@...wei.com>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Thomas Gleixner <tglx@...utronix.de>,
Yu Liao <liaoyu15@...wei.com>,
Boqun Feng <boqun.feng@...il.com>,
"Paul E . McKenney" <paulmck@...nel.org>,
Marcelo Tosatti <mtosatti@...hat.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Uladzislau Rezki <uladzislau.rezki@...y.com>,
Joel Fernandes <joel@...lfernandes.org>
Subject: Re: [PATCH 03/21] rcu: Add a note about noinstr VS unsafe eqs
functions
On Tue, May 03, 2022 at 12:00:33PM +0200, Frederic Weisbecker wrote:
> Some RCU functions enter or exit into/from RCU idle mode while using
> trace-able and lockdep-aware IRQs (un-)masking. This could be easily
> solved with using raw versions of local_irq_*() but we would then
> lose some precious debugging informations.
>
> Another possible way to solve this may consist in using rude RCU-tasks
> in lockdep and irqsoff tracing.
>
> In any case and until this get solved, those RCU functions can't get
> tagged as noinstr even though they should.
FWIW, this also means RCU_NONIDLE() is broken. Luckily there aren't many
users left.
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