From: Petko Manolov <petko.manolov@konsulko.com>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "Paul E . McKenney" <paulmck@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC] WRITE_ONCE_INC() and friends
Date: Sun, 19 Apr 2020 21:29:57 +0300 [thread overview]
Message-ID: <20200419182957.GA36919@carbon> (raw)
In-Reply-To: <491f0b0bc9e4419d93a78974fd7f44c7@AcuMS.aculab.com>
On 20-04-19 18:02:50, David Laight wrote:
> From: Petko Manolov
> > Sent: 19 April 2020 10:45
> > Recently I started reading up on KCSAN and at some point I ran into stuff like:
> >
> > WRITE_ONCE(ssp->srcu_lock_nesting[idx], ssp->srcu_lock_nesting[idx] + 1);
> > WRITE_ONCE(p->mm->numa_scan_seq, READ_ONCE(p->mm->numa_scan_seq) + 1);
>
> If all the accesses use READ/WRITE_ONCE() why not just mark the structure
> field 'volatile'?
This is a bit heavy. I guess you've read this one:
https://lwn.net/Articles/233479/
And no, i am not sure all accesses are through READ/WRITE_ONCE(). If, for
example, all others are from withing spin_lock/unlock pairs then we _may_ not
need READ/WRITE_ONCE().
I merely proposed the _INC() variant for better readability.
Petko
next prev parent reply other threads:[~2020-04-19 18:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-19 9:44 [RFC] WRITE_ONCE_INC() and friends Petko Manolov
2020-04-19 18:02 ` David Laight
2020-04-19 18:29 ` Petko Manolov [this message]
2020-04-19 21:37 ` David Laight
2020-04-20 15:05 ` Paul E. McKenney
2020-04-20 16:32 ` Petko Manolov
2020-04-21 8:00 ` David Laight
2020-04-21 9:30 ` Petko Manolov
2020-04-20 22:57 ` Marco Elver
2020-04-20 23:12 ` Paul E. McKenney
2020-04-21 9:33 ` Marco Elver
2020-04-21 13:19 ` Paul E. McKenney
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