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From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: linux-kernel@vger.kernel.org
Cc: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	byungchul.park@lge.com, kernel-team@android.com
Subject: [PATCH RFC 8/8] rcu: Fix cpustart tracepoint gp_seq number
Date: Sun, 13 May 2018 20:15:41 -0700	[thread overview]
Message-ID: <20180514031541.67247-9-joel@joelfernandes.org> (raw)
In-Reply-To: <20180514031541.67247-1-joel@joelfernandes.org>

cpustart shows a stale gp_seq. This is because rdp->gp_seq is updated
only at the end of the __note_gp_changes function. For this reason, use
rnp->gp_seq instead. I believe we can't update rdp->gp_seq too early so
lets just use the gp_seq from rnp instead.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 25c44328d071..58d2b68f8b98 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1807,7 +1807,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
 		 * set up to detect a quiescent state, otherwise don't
 		 * go looking for one.
 		 */
-		trace_rcu_grace_period(rsp->name, rdp->gp_seq, TPS("cpustart"));
+		trace_rcu_grace_period(rsp->name, rnp->gp_seq, TPS("cpustart"));
 		need_gp = !!(rnp->qsmask & rdp->grpmask);
 		rdp->cpu_no_qs.b.norm = need_gp;
 		rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_dynticks.rcu_qs_ctr);
-- 
2.17.0.441.gb46fe60e1d-goog

  parent reply	other threads:[~2018-05-14  3:16 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-14  3:15 [PATCH RFC 0/8] rcu fixes, clean ups for rcu/dev Joel Fernandes (Google)
2018-05-14  3:15 ` [PATCH RFC 1/8] rcu: Add comment documenting how rcu_seq_snap works Joel Fernandes (Google)
2018-05-14  3:47   ` Randy Dunlap
2018-05-14  5:05     ` Joel Fernandes
2018-05-14 17:38   ` Paul E. McKenney
2018-05-15  1:51     ` Joel Fernandes
2018-05-15  3:59       ` Paul E. McKenney
2018-05-15  7:02         ` Joel Fernandes
2018-05-15 12:55           ` Paul E. McKenney
2018-05-15 18:41             ` Joel Fernandes
2018-05-15 19:08               ` Paul E. McKenney
2018-05-15 22:55                 ` Joel Fernandes
2018-05-16 15:45                   ` Paul E. McKenney
2018-05-16 23:21                     ` Joel Fernandes
2018-05-14  3:15 ` [PATCH RFC 2/8] rcu: Clarify usage of cond_resched for tasks-RCU Joel Fernandes (Google)
2018-05-14 14:54   ` Steven Rostedt
2018-05-14 17:22     ` Paul E. McKenney
2018-05-15  0:35       ` Joel Fernandes
2018-05-15  3:42         ` Paul E. McKenney
2018-05-14  3:15 ` [PATCH RFC 3/8] rcu: Add back the cpuend tracepoint Joel Fernandes (Google)
2018-05-14 18:12   ` Paul E. McKenney
2018-05-15  0:43     ` Joel Fernandes
2018-05-14  3:15 ` [PATCH RFC 4/8] rcu: Get rid of old c variable from places in tree RCU Joel Fernandes (Google)
2018-05-14 17:57   ` Paul E. McKenney
2018-05-15  0:41     ` Joel Fernandes
2018-05-14  3:15 ` [PATCH RFC 5/8] rcu: Use rcu_node as temporary variable in funnel locking loop Joel Fernandes (Google)
2018-05-14 18:00   ` Paul E. McKenney
2018-05-15  0:43     ` Joel Fernandes
2018-05-14  3:15 ` [PATCH RFC 6/8] rcu: Add back the Startedleaf tracepoint Joel Fernandes (Google)
2018-05-14 18:38   ` Paul E. McKenney
2018-05-15  0:57     ` Joel Fernandes
2018-05-15  3:46       ` Paul E. McKenney
2018-05-15 23:04         ` Joel Fernandes
2018-05-16 15:48           ` Paul E. McKenney
2018-05-16 23:13             ` Joel Fernandes
2018-05-14  3:15 ` [PATCH RFC 7/8] rcu: trace CleanupMore condition only if needed Joel Fernandes (Google)
2018-05-14 19:20   ` Paul E. McKenney
2018-05-15  1:01     ` Joel Fernandes
2018-05-15  3:47       ` Paul E. McKenney
2018-05-14  3:15 ` Joel Fernandes (Google) [this message]
2018-05-14 20:33   ` [PATCH RFC 8/8] rcu: Fix cpustart tracepoint gp_seq number Paul E. McKenney
2018-05-15  1:02     ` Joel Fernandes

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