From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <frederic@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Phil Auld <pauld@redhat.com>,
Alex Belits <abelits@marvell.com>,
Nicolas Saenz Julienne <nsaenz@kernel.org>,
Xiongfeng Wang <wangxiongfeng2@huawei.com>,
Neeraj Upadhyay <quic_neeraju@quicinc.com>,
Thomas Gleixner <tglx@linutronix.de>,
Yu Liao <liaoyu15@huawei.com>, Boqun Feng <boqun.feng@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Uladzislau Rezki <uladzislau.rezki@sony.com>,
Joel Fernandes <joel@joelfernandes.org>,
Mark Rutland <mark.rutland@arm.com>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH 16/19] context_tracking: Convert state to atomic_t
Date: Sat, 12 Mar 2022 23:54:09 +0100 [thread overview]
Message-ID: <20220312225409.GH28057@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220302154810.42308-17-frederic@kernel.org>
On Wed, Mar 02, 2022 at 04:48:07PM +0100, Frederic Weisbecker wrote:
> +static __always_inline int __ct_state(void)
> +{
> + return atomic_read(this_cpu_ptr(&context_tracking.state));
> +}
One arguably horrible thing to do would be to write it like:
return __this_cpu_read(context_tracking.state.counter);
IIRC that will actually DTRT since atomic_read() is basically defined to
be READ_ONCE() and this_cpu_read() implies the same.
Only PowerPC and s390 implement arch_atomic_read() in asm, but I don't
think they have a particularly good reason to. The only other weird case
is Alpha, where READ_ONCE() implies smp_mb() because Alpha. I'm not sure
we care about that case, hmm?
The same can be done for ct_dynticks(), which is basically the same
function with a different mask.
As mentioned elsewhere, ct_state() appears unused at the end of the
ride.
next prev parent reply other threads:[~2022-03-12 22:54 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-02 15:47 [PATCH 00/19] rcu/context-tracking: Merge RCU eqs-dynticks counter to context tracking Frederic Weisbecker
2022-03-02 15:47 ` [PATCH 01/19] context_tracking: Rename __context_tracking_enter/exit() to __ct_user_enter/exit() Frederic Weisbecker
2022-03-10 19:27 ` Paul E. McKenney
2022-03-02 15:47 ` [PATCH 02/19] context_tracking: Rename context_tracking_user_enter/exit() to user_enter/exit_callable() Frederic Weisbecker
2022-03-05 13:59 ` Peter Zijlstra
2022-03-09 20:53 ` Frederic Weisbecker
2022-03-02 15:47 ` [PATCH 03/19] context_tracking: Rename context_tracking_enter/exit() to ct_user_enter/exit() Frederic Weisbecker
2022-03-05 14:02 ` Peter Zijlstra
2022-03-09 21:21 ` Frederic Weisbecker
2022-03-02 15:47 ` [PATCH 04/19] context_tracking: Rename context_tracking_cpu_set() to context_tracking_cpu_track_user() Frederic Weisbecker
2022-03-05 14:03 ` Peter Zijlstra
2022-03-09 21:11 ` Frederic Weisbecker
2022-03-02 15:47 ` [PATCH 05/19] context_tracking: Split user tracking Kconfig Frederic Weisbecker
2022-03-10 19:43 ` Paul E. McKenney
2022-03-11 15:49 ` Frederic Weisbecker
2022-03-02 15:47 ` [PATCH 06/19] context_tracking: Take idle eqs entrypoints over RCU Frederic Weisbecker
2022-03-05 14:05 ` Peter Zijlstra
2022-03-09 21:12 ` Frederic Weisbecker
2022-03-02 15:47 ` [PATCH 07/19] context_tracking: Take IRQ " Frederic Weisbecker
2022-03-10 19:46 ` Paul E. McKenney
2022-03-02 15:47 ` [PATCH 08/19] context_tracking: Take NMI " Frederic Weisbecker
2022-03-10 19:47 ` Paul E. McKenney
2022-03-02 15:48 ` [PATCH 09/19] rcu/context-tracking: Remove rcu_irq_enter/exit() Frederic Weisbecker
2022-03-05 14:16 ` Peter Zijlstra
2022-03-09 22:25 ` Frederic Weisbecker
2022-03-02 15:48 ` [PATCH 10/19] rcu/context_tracking: Move dynticks counter to context tracking Frederic Weisbecker
2022-03-10 20:00 ` Paul E. McKenney
2022-03-02 15:48 ` [PATCH 11/19] rcu/context_tracking: Move dynticks_nesting " Frederic Weisbecker
2022-03-10 20:01 ` Paul E. McKenney
2022-03-12 23:23 ` Peter Zijlstra
2022-03-02 15:48 ` [PATCH 12/19] rcu/context_tracking: Move dynticks_nmi_nesting " Frederic Weisbecker
2022-03-10 20:02 ` Paul E. McKenney
2022-03-02 15:48 ` [PATCH 13/19] rcu/context-tracking: Move deferred nocb resched " Frederic Weisbecker
2022-03-10 20:04 ` Paul E. McKenney
2022-03-02 15:48 ` [PATCH 14/19] rcu/context-tracking: Move RCU-dynticks internal functions to context_tracking Frederic Weisbecker
2022-03-10 20:07 ` Paul E. McKenney
2022-03-11 16:02 ` Frederic Weisbecker
2022-03-11 16:14 ` Paul E. McKenney
2022-03-12 23:10 ` Peter Zijlstra
2022-03-02 15:48 ` [PATCH 15/19] rcu/context-tracking: Remove unused and/or unecessary middle functions Frederic Weisbecker
2022-03-09 16:40 ` nicolas saenz julienne
2022-03-11 15:19 ` Frederic Weisbecker
2022-03-02 15:48 ` [PATCH 16/19] context_tracking: Convert state to atomic_t Frederic Weisbecker
2022-03-09 17:17 ` nicolas saenz julienne
2022-03-11 15:24 ` Frederic Weisbecker
2022-03-12 22:54 ` Peter Zijlstra [this message]
2022-03-21 13:32 ` Will Deacon
2022-03-02 15:48 ` [PATCH 17/19] rcu/context-tracking: Use accessor for dynticks counter value Frederic Weisbecker
2022-03-10 20:08 ` Paul E. McKenney
2022-03-02 15:48 ` [PATCH 18/19] rcu/context_tracking: Merge dynticks counter and context tracking states Frederic Weisbecker
2022-03-10 20:32 ` Paul E. McKenney
2022-03-11 16:35 ` Frederic Weisbecker
2022-03-11 17:28 ` Paul E. McKenney
2022-03-02 15:48 ` [PATCH 19/19] context_tracking: Exempt CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK from non-active tracking Frederic Weisbecker
2022-03-08 16:15 ` nicolas saenz julienne
2022-03-11 15:16 ` Frederic Weisbecker
2022-03-11 11:37 ` [PATCH 00/19] rcu/context-tracking: Merge RCU eqs-dynticks counter to context tracking nicolas saenz julienne
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220312225409.GH28057@worktop.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=abelits@marvell.com \
--cc=boqun.feng@gmail.com \
--cc=frederic@kernel.org \
--cc=joel@joelfernandes.org \
--cc=liaoyu15@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mtosatti@redhat.com \
--cc=nsaenz@kernel.org \
--cc=paul.gortmaker@windriver.com \
--cc=pauld@redhat.com \
--cc=paulmck@kernel.org \
--cc=quic_neeraju@quicinc.com \
--cc=tglx@linutronix.de \
--cc=uladzislau.rezki@sony.com \
--cc=wangxiongfeng2@huawei.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox