Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756911AbZFOQIe (ORCPT ); Mon, 15 Jun 2009 12:08:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751849AbZFOQIY (ORCPT ); Mon, 15 Jun 2009 12:08:24 -0400 Received: from mail-fx0-f211.google.com ([209.85.220.211]:36200 "EHLO mail-fx0-f211.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751111AbZFOQIX (ORCPT ); Mon, 15 Jun 2009 12:08:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:mime-version:content-type :content-disposition:in-reply-to:user-agent; b=I6EqgYECN1n58wlisOHvyJmqHRvVdhdDTzoPAi2IGdxZFSEiZ3vnQg0zzyF8QOPZ9G I8VAR/KsznAqWyMPsWnfUNwgl4FTlTMQXx0yMDVXfQQGzRlWxt3eU6//2GVe2x/cgJlQ AMc10t0nCNuX58N7wBpBrldrC6KUJa8btLQHY= Date: Mon, 15 Jun 2009 18:08:01 +0200 From: Jarek Poplawski To: David Miller Cc: Robert Olsson , Yan Zheng , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH 2/1 v2] Re: [BUG] fib_tries related Oops in 2.6.30 Message-ID: <20090615160800.GC2767@ami.dom.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090615065333.GA4378@ff.dom.local> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2870 Lines: 94 Alas this top tnode needs even more. Sorry/thanks, Jarek P. -------------------> take 2 ipv4: Fix fib_trie rebalancing, part 2 My previous patch, which explicitly delays freeing of tnodes by adding them to the list to flush them after the update is finished, isn't strict enough. It treats exceptionally tnodes without parent, assuming they are newly created, so "invisible" for the read side yet. But the top tnode doesn't have parent as well, so we have to exclude all exceptions (at least until a better way is found). Additionally we need to move rcu assignment of this node before flushing, so the return type of the trie_rebalance() function is changed. Reported-by: Yan Zheng Signed-off-by: Jarek Poplawski --- net/ipv4/fib_trie.c | 23 ++++++++++------------- 1 files changed, 10 insertions(+), 13 deletions(-) diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index d1a39b1..6188043 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -391,13 +391,8 @@ static inline void tnode_free(struct tnode *tn) static void tnode_free_safe(struct tnode *tn) { BUG_ON(IS_LEAF(tn)); - - if (node_parent((struct node *) tn)) { - tn->tnode_free = tnode_free_head; - tnode_free_head = tn; - } else { - tnode_free(tn); - } + tn->tnode_free = tnode_free_head; + tnode_free_head = tn; } static void tnode_free_flush(void) @@ -1009,7 +1004,7 @@ fib_find_node(struct trie *t, u32 key) return NULL; } -static struct node *trie_rebalance(struct trie *t, struct tnode *tn) +static void trie_rebalance(struct trie *t, struct tnode *tn) { int wasfull; t_key cindex, key; @@ -1033,12 +1028,14 @@ static struct node *trie_rebalance(struct trie *t, struct tnode *tn) } /* Handle last (top) tnode */ - if (IS_TNODE(tn)) { + if (IS_TNODE(tn)) tn = (struct tnode *)resize(t, (struct tnode *)tn); + + rcu_assign_pointer(t->trie, (struct node *)tn); + if (IS_TNODE(tn)) tnode_free_flush(); - } - return (struct node *)tn; + return; } /* only used from updater-side */ @@ -1186,7 +1183,7 @@ static struct list_head *fib_insert_node(struct trie *t, u32 key, int plen) /* Rebalance the trie */ - rcu_assign_pointer(t->trie, trie_rebalance(t, tp)); + trie_rebalance(t, tp); done: return fa_head; } @@ -1605,7 +1602,7 @@ static void trie_leaf_remove(struct trie *t, struct leaf *l) if (tp) { t_key cindex = tkey_extract_bits(l->key, tp->pos, tp->bits); put_child(t, (struct tnode *)tp, cindex, NULL); - rcu_assign_pointer(t->trie, trie_rebalance(t, tp)); + trie_rebalance(t, tp); } else rcu_assign_pointer(t->trie, NULL); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/