From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>,
linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
Josh Triplett <josh@joshtriplett.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-doc@vger.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Steven Rostedt <rostedt@goodmis.org>,
pantin@google.com
Subject: Re: [PATCH RFC 0/5] rcu doc updates for whatisRCU and checklist
Date: Sat, 6 Oct 2018 18:47:29 -0400 [thread overview]
Message-ID: <20181006224729.GA7130@thunk.org> (raw)
In-Reply-To: <20181006044057.GA41279@joelaf.mtv.corp.google.com>
On Fri, Oct 05, 2018 at 09:40:57PM -0700, Joel Fernandes wrote:
>
> Could you annotate this pointer (sbi->s_qf_names) with __rcu so it can be
> checked by sparse for proper usage? Its also point #16 in the checklist.txt
> RCU document. I enclosed a diff to do this below.
Sure.
> I also saw a bunch of places in super.c where the pointer isn't accessed from
> an rcu read section or rcu_dereference, but it was a quick look so sorry if I
> missed something. If its true, then are you planning to convert these to use
> rcu_dereference and wrapped by an rcu_read_lock/unlock as well?
These are places where we are holding s_umount, so there's no way
s_qf_names can change out from under us. So the conversion should be
to use rcu_dereference_protected().
> > + to_free[i] = rcu_dereference_protected(sbi->s_qf_names[i],
> > + &sb->s_umount);
>
> Also should this be the following?
> to_free[i] = rcu_dereference_protected(sbi->s_qf_names[i],
> lockdep_is_held(&sb->s_umount));
Yep, good catch, thanks.
- Ted
next prev parent reply other threads:[~2018-10-06 22:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-05 23:18 [PATCH RFC 0/5] rcu doc updates for whatisRCU and checklist Joel Fernandes (Google)
2018-10-05 23:18 ` [PATCH RFC 1/5] doc: rcu: Update core and full API in whatisRCU Joel Fernandes (Google)
2018-10-05 23:18 ` [PATCH RFC 2/5] doc: rcu: Add more rationale for using rcu_read_lock_sched in checklist Joel Fernandes (Google)
2018-10-05 23:18 ` [PATCH RFC 3/5] doc: rcu: Remove obsolete suggestion from checklist Joel Fernandes (Google)
2018-10-05 23:18 ` [PATCH RFC 4/5] doc: rcu: Remove obsolete checklist item about synchronize_rcu usage Joel Fernandes (Google)
2018-10-05 23:18 ` [PATCH RFC 5/5] doc: rcu: Encourage use of rcu_barrier in checklist Joel Fernandes (Google)
2018-10-05 23:46 ` [PATCH RFC 0/5] rcu doc updates for whatisRCU and checklist Theodore Y. Ts'o
2018-10-06 1:59 ` Joel Fernandes
2018-10-06 3:45 ` Paul E. McKenney
2018-10-06 4:40 ` Joel Fernandes
2018-10-06 22:47 ` Theodore Y. Ts'o [this message]
2018-10-06 4:50 ` Joel Fernandes
2018-10-06 5:34 ` Theodore Y. Ts'o
2018-10-06 16:49 ` Paul E. McKenney
2018-10-06 0:13 ` Paul E. McKenney
2018-10-06 2:10 ` Joel Fernandes
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