All of lore.kernel.org
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Jeff Layton <jlayton@kernel.org>,
	John Stultz <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>
Cc: Vadim Fedorenko <vadim.fedorenko@linux.dev>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] timekeeping: don't use seqcount loop in ktime_mono_to_any on 64-bit arch
Date: Tue, 10 Sep 2024 17:39:54 +0200	[thread overview]
Message-ID: <87ttena56d.ffs@tglx> (raw)
In-Reply-To: <ee39e467d23070c00aa39f12895fe346406f527f.camel@kernel.org>

On Tue, Sep 10 2024 at 08:32, Jeff Layton wrote:
> On Tue, 2024-09-10 at 13:58 +0200, Thomas Gleixner wrote:
>> > +#if BITS_PER_LONG == 64
>> > +ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs)
>> > +{
>> > +	ktime_t *offset = offsets[offs];
>> > +
>> > +	return ktime_add(tmono, READ_ONCE(*offset));
>> 
>> Where is the corresponing WRITE_ONCE()?
>> 
> I'll just make it do a simple fetch without READ_ONCE.

Which will make KCSAN complain ...

So yes, READ_ONCE() is the correct thing todo, but then we want to have
the counterpart at the write sides.

Thanks,

        tglx

      reply	other threads:[~2024-09-10 15:39 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-10 11:17 [PATCH RFC] timekeeping: don't use seqcount loop in ktime_mono_to_any on 64-bit arch Jeff Layton
2024-09-10 11:58 ` Thomas Gleixner
2024-09-10 12:32   ` Jeff Layton
2024-09-10 15:39     ` Thomas Gleixner [this message]

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=87ttena56d.ffs@tglx \
    --to=tglx@linutronix.de \
    --cc=jlayton@kernel.org \
    --cc=jstultz@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=sboyd@kernel.org \
    --cc=vadim.fedorenko@linux.dev \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.