From: "Ted Ts'o" <tytso@mit.edu>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] jbd2,rcu: correctly use RCU
Date: Sun, 10 Jul 2011 21:24:29 -0400 [thread overview]
Message-ID: <20110711012429.GD28763@thunk.org> (raw)
In-Reply-To: <ec67960d0864680d18a43ec5275baba3f6e1dd94.1308131436.git.laijs@cn.fujitsu.com>
On Thu, Jun 16, 2011 at 09:47:04AM +0800, Lai Jiangshan wrote:
> In read site, we need to use local_ptr = rcu_dereference(),
> and then use this local_ptr to read the content.
>
> In update site, we should assign/publish the new object/pointer after
> the content of the new object/pointer is fully initialized,
> and we can't not touch the object after the pointer assignment.
> rcu_assign_pointer() is need for the assignement.
>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Actually, after thinking about this some more, I think I'm going to
just change the jbd2 events to simply print MAJOR(__entry->dev) and
MINOR(__entry->dev). Otherwise, the perf tool stops dies and stops
interpreting the trace points when it tries to interpret
"jbd2_dev_to_name(REC->dev)" in the print format.
So I'll just drop jbd2_dev_to_name() completely for the jbd2
tracepoints. It's not worth it.
- Ted
prev parent reply other threads:[~2011-07-11 1:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-16 1:47 [PATCH 1/3] jbd2,rcu: correctly use RCU Lai Jiangshan
2011-06-16 1:47 ` [PATCH 2/3] jbd2,tracing,rcu: jbd2_dev_to_name() is not protect by RCU Lai Jiangshan
2011-07-08 2:06 ` Steven Rostedt
2011-07-08 16:02 ` Paul E. McKenney
2011-06-16 1:47 ` [PATCH 3/3] jbd2,rcu: simpify jbd2_dev_to_name() Lai Jiangshan
2011-07-11 0:25 ` [PATCH 1/3] jbd2,rcu: correctly use RCU Ted Ts'o
2011-07-11 1:24 ` Ted Ts'o [this message]
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