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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. R. Okajima" <hooanon05g@gmail.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	George Spelvin <linux@sciencehorizons.net>
Subject: Re: Q. hlist_bl_add_head_rcu() in d_alloc_parallel()
Date: Sat, 25 Jun 2016 18:25:58 -0700	[thread overview]
Message-ID: <CA+55aFyboLUOqNgDSF9_3iK9ECRFP821Bzmd88ABHj7xSGwWUw@mail.gmail.com> (raw)
In-Reply-To: <20160625225423.GV14480@ZenIV.linux.org.uk>

On Sat, Jun 25, 2016 at 3:54 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> BTW, speaking of that area - is there any reason why dentry_cmp()
> isn't simply
>         return dentry_string_cmp(lockless_dereference(dentry->d_name.name),
>                                  ct, tcount);
> other than "it predates lockless_dereference()"?

No, the only important thing is that it's a read-once, and has the
smp_read_barrier_depends().

So lockless_derefence() looks like the right thing to do, it is just
that - as you suspected - the code predates that concept.

               Linus

  reply	other threads:[~2016-06-26  1:26 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-17 20:50 Q. hlist_bl_add_head_rcu() in d_alloc_parallel() J. R. Okajima
2016-06-17 22:16 ` Al Viro
2016-06-17 22:56   ` Al Viro
2016-06-19  5:24   ` J. R. Okajima
2016-06-19 16:55     ` Al Viro
2016-06-20  4:34       ` J. R. Okajima
2016-06-20  5:35         ` Al Viro
2016-06-20 14:51           ` Al Viro
2016-06-20 17:14             ` [git pull] vfs fixes Al Viro
2016-06-23  1:19           ` Q. hlist_bl_add_head_rcu() in d_alloc_parallel() J. R. Okajima
2016-06-23  2:58             ` Al Viro
2016-06-24  5:57               ` Linus Torvalds
2016-06-25 22:54                 ` Al Viro
2016-06-26  1:25                   ` Linus Torvalds [this message]
2016-06-29  8:17                     ` Al Viro
2016-06-29  9:22                       ` Hekuang

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