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Date: Mon, 9 Oct 2017 20:31:16 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org, mingo@...nel.org,
torvalds@...ux-foundation.org, mark.rutland@....com,
dhowells@...hat.com, linux-arch@...r.kernel.org,
peterz@...radead.org, will.deacon@....com,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH RFC tip/core/rcu 11/15] tracepoint: Remove
smp_read_barrier_depends() from comment
[ added Mathieu ]
On Mon, 9 Oct 2017 17:22:45 -0700
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
> The comment in tracepoint_add_func() mentions smp_read_barrier_depends(),
> whose use should be quite restricted. This commit updates the comment
> to instead mention the smp_store_release() and rcu_dereference_sched()
> that the current code actually uses.
>
> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
Acked-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
-- Steve
> ---
> kernel/tracepoint.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index 685c50ae6300..671b13457387 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -212,11 +212,10 @@ static int tracepoint_add_func(struct tracepoint *tp,
> }
>
> /*
> - * rcu_assign_pointer has a smp_wmb() which makes sure that the new
> - * probe callbacks array is consistent before setting a pointer to it.
> - * This array is referenced by __DO_TRACE from
> - * include/linux/tracepoints.h. A matching smp_read_barrier_depends()
> - * is used.
> + * rcu_assign_pointer has as smp_store_release() which makes sure
> + * that the new probe callbacks array is consistent before setting
> + * a pointer to it. This array is referenced by __DO_TRACE from
> + * include/linux/tracepoint.h using rcu_dereference_sched().
> */
> rcu_assign_pointer(tp->funcs, tp_funcs);
> if (!static_key_enabled(&tp->key))
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