netdev - [PATCH net-next 10/16] ipv6: don't release rt->rt6i_pcpu memory during rt6

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Message-Id: <20171006190611.110633-11-tracywwnj@gmail.com>
Date:   Fri,  6 Oct 2017 12:06:05 -0700
From:   Wei Wang <weiwan@...gle.com>
To:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     Eric Dumazet <edumazet@...gle.com>,
        Martin KaFai Lau <kafai@...com>, Wei Wang <weiwan@...gle.com>
Subject: [PATCH net-next 10/16] ipv6: don't release rt->rt6i_pcpu memory during rt6_release()

From: Wei Wang <weiwan@...gle.com>

After rwlock is replaced with rcu and spinlock, route lookup can happen
simultanously with route deletion.
This patch removes the call to free_percpu(rt->rt6i_pcpu) from
rt6_release() to avoid the race condition between rt6_release() and
rt6_get_pcpu_route(). And as free_percpu(rt->rt6i_pcpu) is already
called in ip6_dst_destroy() after the rcu grace period, it is safe to do
this change.

Signed-off-by: Wei Wang <weiwan@...gle.com>
Signed-off-by: Martin KaFai Lau <kafai@...com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/ip6_fib.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 9c8e704e6af7..eee392f7b1f6 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -190,9 +190,6 @@ void rt6_free_pcpu(struct rt6_info *non_pcpu_rt)
 			*ppcpu_rt = NULL;
 		}
 	}
-
-	free_percpu(non_pcpu_rt->rt6i_pcpu);
-	non_pcpu_rt->rt6i_pcpu = NULL;
 }
 EXPORT_SYMBOL_GPL(rt6_free_pcpu);
 
-- 
2.14.2.920.gcf0c67979c-goog