From: Andrea Parri <andrea.parri@amarulasolutions.com>
To: David Howells <dhowells@redhat.com>
Cc: paulmck@linux.vnet.ibm.com, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Andrea Parri <parri.andrea@gmail.com>,
Alan Stern <stern@rowland.harvard.edu>,
Will Deacon <will.deacon@arm.com>,
Boqun Feng <boqun.feng@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
Jade Alglave <j.alglave@ucl.ac.uk>,
Luc Maranget <luc.maranget@inria.fr>,
Akira Yokosawa <akiyks@gmail.com>
Subject: Re: [PATCH v2 1/3] locking: Document the semantics of spin_is_locked()
Date: Tue, 3 Apr 2018 16:07:15 +0200 [thread overview]
Message-ID: <20180403140715.GA5375@andrea> (raw)
In-Reply-To: <13191.1522763553@warthog.procyon.org.uk>
On Tue, Apr 03, 2018 at 02:52:33PM +0100, David Howells wrote:
> Andrea Parri <andrea.parri@amarulasolutions.com> wrote:
>
> > > It's more complicated than that. This function is dangerous and should be
> > > used with extreme care. In the case where CONFIG_SMP=n the value is locked
> > > one way or the other and it might be the wrong way.
> >
> > You mean "unlocked"? (aka, return 0)
>
> No, I mean "fixed", sorry. We've had problems stemming from this before on UP
> systems.
Sorry, but I don't understand your objection: are you suggesting to add
something like "Always return 0 on !SMP" to the comment? what else?
Andrea
>
> David
next prev parent reply other threads:[~2018-04-03 14:07 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-01 16:41 [PATCH v3 0/3] Changes, clean-ups and documentation for spin_is_locked() Andrea Parri
2018-04-01 16:41 ` [PATCH v2 1/3] locking: Document the semantics of spin_is_locked() Andrea Parri
2018-04-02 14:03 ` Alan Stern
2018-04-02 19:35 ` Paul E. McKenney
2018-04-03 12:49 ` David Howells
2018-04-03 13:35 ` Andrea Parri
2018-04-03 13:52 ` David Howells
2018-04-03 14:07 ` Andrea Parri [this message]
2018-04-03 15:23 ` David Howells
2018-04-03 19:31 ` Andrea Parri
2018-04-03 20:04 ` Alan Stern
2018-04-03 21:43 ` David Howells
2018-04-03 21:47 ` Randy Dunlap
2018-04-04 21:22 ` David Howells
2018-04-04 12:47 ` Andrea Parri
2018-04-03 14:17 ` Paul E. McKenney
2018-04-03 14:43 ` Peter Zijlstra
2018-04-03 15:03 ` Paul E. McKenney
2018-04-03 16:11 ` Paul E. McKenney
2018-04-05 7:47 ` Christoph Hellwig
2018-04-05 8:56 ` Andrea Parri
2018-04-06 19:47 ` [PATCH v4 " Andrea Parri
2018-04-06 21:00 ` Paul E. McKenney
2018-04-06 21:01 ` Randy Dunlap
2018-04-06 21:07 ` Paul E. McKenney
2018-04-06 21:08 ` Randy Dunlap
2018-04-06 21:58 ` Andrea Parri
2018-04-08 21:14 ` Paul E. McKenney
2018-04-08 21:32 ` Randy Dunlap
2018-04-08 22:00 ` Paul E. McKenney
2018-04-01 16:41 ` [PATCH v3 2/3] arm64: Remove smp_mb() from arch_spin_is_locked() Andrea Parri
2018-04-01 16:41 ` [PATCH v3 3/3] locking: Clean up comment and #ifndef for {,queued_}spin_is_locked() Andrea Parri
2018-04-01 18:24 ` [PATCH v3 0/3] Changes, clean-ups and documentation for spin_is_locked() Paul E. McKenney
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