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From: Peter Zijlstra <peterz@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Waiman Long <longman@redhat.com>, Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Davidlohr Bueso <dave@stgolabs.net>,
	"Theodore Y. Ts'o" <tytso@mit.edu>,
	Oleg Nesterov <oleg@redhat.com>,
	Amir Goldstein <amir73il@gmail.com>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH v3 2/2] locking/percpu-rwsem: Annotate rwsem ownership transfer by setting RWSEM_OWNER_UNKNOWN
Date: Tue, 15 May 2018 20:07:10 +0200	[thread overview]
Message-ID: <20180515180710.GQ12217@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180515180219.GA6612@bombadil.infradead.org>

On Tue, May 15, 2018 at 11:02:19AM -0700, Matthew Wilcox wrote:
> On Tue, May 15, 2018 at 07:58:05PM +0200, Peter Zijlstra wrote:
> > On Tue, May 15, 2018 at 01:38:04PM -0400, Waiman Long wrote:
> > > +/*
> > > + * Owner value to indicate the rwsem's owner is not currently known.
> > > + */
> > > +#define RWSEM_OWNER_UNKNOWN	((struct task_struct *)-1)
> > 
> > It might be nice to comment that this works and relies on having that
> > ANON_OWNER bit set.
> 
> I'd rather change the definition to be ((struct task_struct *)2)
> otherwise this is both reader-owned and anonymously-owned which doesn't
> make much sense.

Works for me.

  reply	other threads:[~2018-05-15 18:07 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-15 17:38 [PATCH v3 0/2] locking/rwsem: Fix DEBUG_RWSEM warning from thaw_super() Waiman Long
2018-05-15 17:38 ` [PATCH v3 1/2] locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flag Waiman Long
2018-05-15 17:46   ` Peter Zijlstra
2018-05-15 17:48     ` Waiman Long
2018-05-15 17:48   ` Peter Zijlstra
2018-05-15 17:52     ` Waiman Long
2018-05-15 17:55       ` Peter Zijlstra
2018-05-15 17:56         ` Waiman Long
2018-05-15 18:02   ` Peter Zijlstra
2018-05-15 17:38 ` [PATCH v3 2/2] locking/percpu-rwsem: Annotate rwsem ownership transfer by setting RWSEM_OWNER_UNKNOWN Waiman Long
2018-05-15 17:58   ` Peter Zijlstra
2018-05-15 18:02     ` Waiman Long
2018-05-15 18:05       ` Amir Goldstein
2018-05-15 18:45         ` Waiman Long
2018-05-15 18:05       ` Peter Zijlstra
2018-05-15 18:35         ` Waiman Long
2018-05-15 18:02     ` Matthew Wilcox
2018-05-15 18:07       ` Peter Zijlstra [this message]
2018-05-15 18:45       ` Waiman Long
2018-05-15 21:21         ` Matthew Wilcox
2018-05-15 21:30           ` Waiman Long

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