From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ying Xue Subject: [PATCH net-next] tipc: fix RCU sparse error Date: Wed, 10 Dec 2014 11:00:07 +0800 Message-ID: <1418180407-1847-1-git-send-email-ying.xue@windriver.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , , , To: Return-path: Received: from mail1.windriver.com ([147.11.146.13]:52413 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751550AbaLJDAi (ORCPT ); Tue, 9 Dec 2014 22:00:38 -0500 Sender: netdev-owner@vger.kernel.org List-ID: The commit 97ede29e80ee ("tipc: convert name table read-write lock to RCU") involves the following sparse when using make ARCH=x86_64 allmodconfig make C=1 CF=-D__CHECK_ENDIAN__ net/tipc/name_table.c:1136:17: sparse: incompatible types in comparison expression (different address spaces) net/tipc/name_table.c:1136:17: sparse: incompatible types in comparison expression (different address spaces) To silence above spare complaint, an RCU annotation should be added to next pointer of hlist_node structure through hlist_next_rcu() macro when iterating over a hlist with hlist_for_each_entry_from_rcu(). By the way, this commit also simplifies the way of dereferencing the first element of a hlist_head list by replacing hlist_for_each_entry_rcu() with hlist_entry_safe(). Reported-by: Kbuild test robot Cc: Kbuild test robot Signed-off-by: Ying Xue --- include/linux/rculist.h | 4 ++-- net/tipc/name_table.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/include/linux/rculist.h b/include/linux/rculist.h index aa79b3c..866d9c9 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -549,8 +549,8 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n, */ #define hlist_for_each_entry_from_rcu(pos, member) \ for (; pos; \ - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\ - typeof(*(pos)), member)) + pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ + &(pos)->member)), typeof(*(pos)), member)) #endif /* __KERNEL__ */ #endif diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c index c8df022..fa4341f 100644 --- a/net/tipc/name_table.c +++ b/net/tipc/name_table.c @@ -1110,7 +1110,7 @@ static int __tipc_nl_seq_list(struct tipc_nl_msg *msg, u32 *last_type, u32 *last_lower, u32 *last_publ) { struct hlist_head *seq_head; - struct name_seq *seq = NULL; + struct name_seq *seq; int err; int i; @@ -1127,8 +1127,8 @@ static int __tipc_nl_seq_list(struct tipc_nl_msg *msg, u32 *last_type, if (!seq) return -EPIPE; } else { - hlist_for_each_entry_rcu(seq, seq_head, ns_list) - break; + seq = hlist_entry_safe(rcu_dereference_raw( + hlist_first_rcu(seq_head)), struct name_seq, ns_list); if (!seq) continue; } -- 1.7.9.5