mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: linke li <lilinke99@qq.com>
To: joel@joelfernandes.org
Cc: boqun.feng@gmail.com, dave@stgolabs.net, frederic@kernel.org,
	jiangshanlai@gmail.com, josh@joshtriplett.org, lilinke99@qq.com,
	linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com,
	paulmck@kernel.org, qiang.zhang1211@gmail.com,
	quic_neeraju@quicinc.com, rcu@vger.kernel.org,
	rostedt@goodmis.org
Subject: Re: [PATCH] rcutorture: Fix rcu_torture_pipe_update_one()/rcu_torture_writer() data race and concurrency bug
Date: Tue,  5 Mar 2024 14:24:20 +0800	[thread overview]
Message-ID: <tencent_9882B228F292088CDD68F10CF1C228742009@qq.com> (raw)
In-Reply-To: <f3624f39-bbb1-451d-8161-8518e4108d8e@joelfernandes.org>

> Anyway, a slightly related/different question:
> 
> Should that:
> WRITE_ONCE(rp->rtort_pipe_count, rp->rtort_pipe_count + 1);
> 
> Be:
> WRITE_ONCE(rp->rtort_pipe_count, READ_ONCE(rp->rtort_pipe_count) + 1);
> 
> ?

Hi, Joel. Sorry, I am not very sure about this. I do a little research on
it.

I looked through all code in kernel that looks like this, both kinds are
used. I also try to compile this file with and without the READ_ONCE in
WRITE_ONCE using gcc-9. Their binary is just the same. 

Thus I think in the current compiler version, they do not have a big
difference, but if the compiler wants to optimize more, maybe the latter
one is better.


  parent reply	other threads:[~2024-03-05  6:24 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-04 10:54 linke li
2024-03-04 16:19 ` Joel Fernandes
2024-03-04 17:14   ` Paul E. McKenney
2024-03-04 19:10     ` Joel Fernandes
2024-03-04 19:44       ` Paul E. McKenney
2024-03-04 20:13         ` Joel Fernandes
2024-03-04 20:47           ` Paul E. McKenney
2024-03-05  3:30             ` linke
2024-03-05  6:24   ` linke li [this message]
2024-03-06 15:37     ` Steven Rostedt
2024-03-06 17:36       ` Paul E. McKenney
2024-03-06 18:01         ` Steven Rostedt
2024-03-06 18:09           ` Paul E. McKenney
2024-03-06 18:20             ` Steven Rostedt
2024-03-06 18:43           ` Linus Torvalds
2024-03-06 18:55             ` Steven Rostedt
2024-03-06 19:01               ` Linus Torvalds
2024-03-06 19:27                 ` Linus Torvalds
2024-03-06 19:47                   ` Steven Rostedt
2024-03-06 20:06                     ` Linus Torvalds
2024-03-07 13:20                       ` Steven Rostedt
2024-03-07 16:12                         ` Steven Rostedt
2024-03-06 19:27                 ` Steven Rostedt
2024-03-06 19:46                   ` Linus Torvalds
2024-03-06 20:20                     ` Linus Torvalds
2024-03-07  2:29                     ` Paul E. McKenney
2024-03-07  2:43                       ` Linus Torvalds
2024-03-07  2:49                         ` Linus Torvalds
2024-03-07  3:21                           ` Paul E. McKenney
2024-03-07  3:06                         ` Paul E. McKenney
2024-03-07  3:06                         ` Mathieu Desnoyers
2024-03-07  3:37                           ` Paul E. McKenney
2024-03-07  5:44                             ` Joel Fernandes
2024-03-07 19:05                               ` Paul E. McKenney
2024-03-07 13:53                             ` Mathieu Desnoyers
2024-03-07 19:47                               ` Paul E. McKenney
2024-03-07 19:53                                 ` Mathieu Desnoyers
2024-03-08  0:58                                   ` Paul E. McKenney
2024-03-07 20:00                                 ` Linus Torvalds
2024-03-07 20:57                                   ` Paul E. McKenney
2024-03-07 21:40                                     ` Julia Lawall
2024-03-07 22:09                                       ` Linus Torvalds
2024-03-08  0:55                                         ` Paul E. McKenney

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=tencent_9882B228F292088CDD68F10CF1C228742009@qq.com \
    --to=lilinke99@qq.com \
    --cc=boqun.feng@gmail.com \
    --cc=dave@stgolabs.net \
    --cc=frederic@kernel.org \
    --cc=jiangshanlai@gmail.com \
    --cc=joel@joelfernandes.org \
    --cc=josh@joshtriplett.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=paulmck@kernel.org \
    --cc=qiang.zhang1211@gmail.com \
    --cc=quic_neeraju@quicinc.com \
    --cc=rcu@vger.kernel.org \
    --cc=rostedt@goodmis.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
all inboxes | Powered by JetHome®