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From: Tejun Heo <tj@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com>,
	linux-kernel@vger.kernel.org,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH 1/2] trace_events_filter: use rcu_assign_pointer() when setting ftrace_event_call->filter
Date: Wed, 23 Nov 2011 08:12:03 -0800	[thread overview]
Message-ID: <20111123161203.GC25780@google.com> (raw)
In-Reply-To: <20111123160653.GB25780@google.com>

On Wed, Nov 23, 2011 at 08:06:53AM -0800, Tejun Heo wrote:
> otherwise, it may fetch the old values from before the new area is
> initialized on archs where data dependency barrier isn't noop.

I think this can be a problem on archs where dd barrier is noop but
wmb is not.  dd barrier is implied on every read access but nothing
guarantees the updating CPU sends out write for the pointer assignment
before initialization of the new area.

Thanks.

-- 
tejun

  reply	other threads:[~2011-11-23 16:12 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-23  1:46 [PATCH 1/2] trace_events_filter: use rcu_assign_pointer() when setting ftrace_event_call->filter Tejun Heo
2011-11-23  2:00 ` [PATCH 2/2] trace_event_filter: factorize filter creation Tejun Heo
2011-11-23 15:19   ` Steven Rostedt
2011-11-23 15:59     ` Tejun Heo
2011-11-28 20:49   ` Tejun Heo
2011-11-28 22:15     ` Steven Rostedt
2011-12-08 23:32       ` Tejun Heo
2011-12-09  0:15         ` Steven Rostedt
2011-12-09  0:46         ` Steven Rostedt
2011-12-09 18:55           ` Tejun Heo
2011-12-09 19:43   ` [PATCH 2/2 UPDATED] " Tejun Heo
2011-11-23 15:16 ` [PATCH 1/2] trace_events_filter: use rcu_assign_pointer() when setting ftrace_event_call->filter Steven Rostedt
2011-11-23 16:06   ` Tejun Heo
2011-11-23 16:12     ` Tejun Heo [this message]
2011-11-23 17:06     ` Steven Rostedt
2011-11-23 17:33       ` Tejun Heo
2011-11-28 16:49         ` Paul E. McKenney
2011-11-23 16:40 ` Eric Dumazet
2011-11-23 16:44   ` Tejun Heo
2011-11-23 16:49 ` [PATCH UPDATED " Tejun Heo
2011-12-05 17:34   ` [tip:perf/urgent] trace_events_filter: Use " tip-bot for Tejun Heo

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