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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, torvalds@linux-foundation.org,
	mark.rutland@arm.com, dhowells@redhat.com,
	linux-arch@vger.kernel.org, peterz@infradead.org,
	will.deacon@arm.com,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH RFC tip/core/rcu 11/15] tracepoint: Remove smp_read_barrier_depends() from comment
Date: Mon,  9 Oct 2017 17:22:45 -0700	[thread overview]
Message-ID: <1507594969-8347-11-git-send-email-paulmck@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171010001951.GA6476@linux.vnet.ibm.com>

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@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 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))
-- 
2.5.2

  parent reply	other threads:[~2017-10-10  0:23 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-10  0:19 [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 01/15] doc: READ_ONCE() now implies smp_barrier_depends() Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 02/15] mn10300: READ_ONCE() now implies smp_read_barrier_depends() Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 03/15] drivers/net/ethernet/qlogic/qed: Fix __qed_spq_block() ordering Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 04/15] fs/dcache: Use release-acquire for name/length update Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 05/15] percpu: READ_ONCE() now implies smp_read_barrier_depends() Paul E. McKenney
2017-10-10 14:08   ` Tejun Heo
2017-10-10 15:30     ` Paul E. McKenney
2017-10-10 15:49       ` Tejun Heo
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 06/15] rcu: Adjust read-side accessor comments for READ_ONCE() Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 07/15] rtnetlink: Update now-misleading smp_read_barrier_depends() comment Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 08/15] seqlock: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 09/15] uprobes: " Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 10/15] locking: Remove smp_read_barrier_depends() from queued_spin_lock_slowpath() Paul E. McKenney
2017-10-10  0:22 ` Paul E. McKenney [this message]
2017-10-10  0:31   ` [PATCH RFC tip/core/rcu 11/15] tracepoint: Remove smp_read_barrier_depends() from comment Steven Rostedt
2017-10-10  1:12     ` Mathieu Desnoyers
2017-10-10 15:32       ` Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() Paul E. McKenney
2017-10-10  8:39   ` Peter Zijlstra
2017-10-10  9:36   ` David Howells
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 13/15] mm/ksm: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 14/15] netfilter: " Paul E. McKenney
2017-10-10  8:43   ` Peter Zijlstra
2017-10-10 15:56     ` Paul E. McKenney
2017-10-10  0:22 ` [PATCH RFC tip/core/rcu 15/15] keyring: " Paul E. McKenney
2017-10-10  9:35 ` [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() David Howells
2017-10-10 15:50   ` Paul E. McKenney
2017-10-10 15:54     ` Peter Zijlstra
2017-10-10 16:05       ` Paul E. McKenney
2017-10-11 12:19   ` David Howells
2017-10-11 12:22     ` Will Deacon
2017-10-11 12:54       ` Paul E. McKenney
2017-10-11 14:18         ` Will Deacon
2017-10-11 14:50           ` Paul E. McKenney
2017-10-11 12:58     ` Paul E. McKenney
2017-10-11 15:17     ` David Howells
2017-10-11 15:59       ` Paul E. McKenney
2017-10-11 16:12         ` Peter Zijlstra
2017-10-11 16:24           ` Peter Zijlstra
2017-10-11 16:47             ` Paul E. McKenney
2017-10-11 16:54               ` Peter Zijlstra
2017-10-11 17:06                 ` Paul E. McKenney
2017-10-11 17:11                   ` Peter Zijlstra
2017-10-11 17:34                     ` Paul E. McKenney
2017-10-11 18:43                       ` Dmitry Vyukov
2017-10-11 18:56                         ` Linus Torvalds
2017-10-11 19:28                           ` Paul E. McKenney
2017-10-11 19:59                           ` Dmitry Vyukov
2017-10-11 17:14                   ` Paul E. McKenney
2017-10-11 17:19             ` Mark Rutland
2017-10-11 16:50           ` Paul E. McKenney
2017-10-11 16:07       ` David Howells
2017-10-11 16:17         ` Peter Zijlstra
2017-10-11 16:19         ` Paul E. McKenney
2017-10-11 15:28     ` David Howells
2017-10-11 16:02       ` Paul E. McKenney
2017-10-10  9:59 ` David Howells
2017-10-10 15:52   ` Paul E. McKenney
2017-10-11 12:21 ` [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() David Howells
2017-10-11 12:56   ` Paul E. McKenney

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