netdev - [v3 PATCH 1/9] rhashtable: Add barrier to ensure we see new tables in walker

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Date:	Tue, 24 Mar 2015 00:50:19 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"David S. Miller" <davem@...emloft.net>,
	Thomas Graf <tgraf@...g.ch>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Patrick McHardy <kaber@...sh.net>,
	Josh Triplett <josh@...htriplett.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	netdev@...r.kernel.org
Subject: [v3 PATCH 1/9] rhashtable: Add barrier to ensure we see new tables in walker

The walker is a lockless reader so it too needs an smp_rmb before
reading the future_tbl field in order to see any new tables that
may contain elements that we should have walked over.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Acked-by: Thomas Graf <tgraf@...g.ch>
---

 lib/rhashtable.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 83cfedd..618a3f0 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -477,6 +477,9 @@ next:
 		iter->skip = 0;
 	}
 
+	/* Ensure we see any new tables. */
+	smp_rmb();
+
 	iter->walker->tbl = rht_dereference_rcu(tbl->future_tbl, ht);
 	if (iter->walker->tbl) {
 		iter->slot = 0;
--
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