From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: David Woodhouse <dwmw2@infradead.org>,
"Paul E . McKenney" <paulmck@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <joelagnelf@nvidia.com>,
Josh Triplett <josh@joshtriplett.org>,
Boqun Feng <boqun@kernel.org>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang@linux.dev>,
Davidlohr Bueso <dave@stgolabs.net>,
Kunwu Chan <kunwu.chan@gmail.com>,
Puranjay Mohan <puranjay@kernel.org>,
rcu@vger.kernel.org
Subject: Re: [PATCH v2 0/7] srcu: NMI-safe atomic SRCU readers, and their irqsave forms
Date: Wed, 11 Nov 2026 14:33:18 -0500 [thread overview]
Message-ID: <0782c3e7-9766-440c-b21e-e89b822927ee@efficios.com> (raw)
In-Reply-To: <50d177ddb1de4b84e9fd2cbd2ec5bdb7e32845d4.camel@infradead.org>
On 2026-11-11 14:02, David Woodhouse wrote:
> The latter claim is only true in __srcu_read_lock_fast()/_fast_updown()
> isn't it? Not in the atomic-SRCU. Unless we do something like this on
> top?
It is true for the atomic readers as well. Without
CONFIG_NEED_SRCU_NMI_SAFE, include/linux/srcu.h defines
__srcu_read_lock_nmisafe() as an inline that calls __srcu_read_lock(),
and the same for unlock. So x86 keeps this_cpu_inc() and smp_mb().
Your diff selects the same functions by hand.
Only the architectures that select NEED_SRCU_NMI_SAFE get the atomic
increments.
> I set a test running (*without* the above).
Thanks!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
next prev parent reply other threads:[~2026-11-11 19:33 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-11 14:59 Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 1/7] srcutiny: Do not call synchronize_rcu() from synchronize_srcu_atomic() Mathieu Desnoyers
2026-11-11 18:35 ` Paul E. McKenney
2026-11-11 14:59 ` [PATCH v2 2/7] srcu: Rule for using synchronize_srcu_atomic() from interrupt handlers Mathieu Desnoyers
2026-11-11 18:54 ` Paul E. McKenney
2026-11-11 14:59 ` [PATCH v2 3/7] srcu: Make atomic SRCU readers NMI-safe Mathieu Desnoyers
2026-11-11 19:55 ` Paul E. McKenney
2026-11-11 14:59 ` [PATCH v2 4/7] srcu: Add irqsave variants of the atomic SRCU readers Mathieu Desnoyers
2026-11-11 19:58 ` Paul E. McKenney
2026-11-11 20:04 ` Paul E. McKenney
2026-11-11 20:13 ` Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 5/7] rcutorture: Run NMI-safe SRCU readers from NMI Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 6/7] rcutorture: Test the irqsave forms of atomic SRCU readers Mathieu Desnoyers
2026-11-11 14:59 ` [PATCH v2 7/7] rcutorture: Check an atomic SRCU wait within an RCU reader Mathieu Desnoyers
2026-11-11 19:02 ` [PATCH v2 0/7] srcu: NMI-safe atomic SRCU readers, and their irqsave forms David Woodhouse
2026-11-11 19:33 ` Mathieu Desnoyers [this message]
2026-11-11 19:35 ` Paul E. McKenney
2026-11-11 19:37 ` David Woodhouse
2026-11-11 19:40 ` Mathieu Desnoyers
2026-11-11 19:50 ` Paul E. McKenney
2026-11-11 19:34 ` Paul E. McKenney
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