Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964858AbbLSO6f (ORCPT ); Sat, 19 Dec 2015 09:58:35 -0500 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:37218 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753880AbbLSO6e (ORCPT ); Sat, 19 Dec 2015 09:58:34 -0500 X-IronPort-AV: E=Sophos;i="5.20,449,1444687200"; d="scan'208";a="193113600" Date: Sat, 19 Dec 2015 15:58:29 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Geliang Tang cc: "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/14 v2] ipv4, ipv6: use list_for_each_entry* In-Reply-To: <08ea3b12ed228d7252ca6b14e2033c2bee20f78e.1450535467.git.geliangtang@163.com> Message-ID: References: <08ea3b12ed228d7252ca6b14e2033c2bee20f78e.1450535467.git.geliangtang@163.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5993 Lines: 182 On Sat, 19 Dec 2015, Geliang Tang wrote: > Use list_for_each_entry*() instead of list_for_each*() to simplify > the code. Is the code really simpler? At least in the case of net/ipv6/addrconf.c, I have the impression that there can be an access from a pointer that is not really pointing to the thing indicated by its type. The code seems to work, but this doesn't seem like a good property for it to have. In these cases, you need access to both the list and to the entry. The original code seemed like a reasonable way to express that. julia > Signed-off-by: Geliang Tang > --- > Changes in v2: > - bugfix for inet6_register_protosw in v1. > --- > net/ipv4/af_inet.c | 11 ++++------- > net/ipv4/tcp_output.c | 6 ++---- > net/ipv6/addrconf.c | 8 +++----- > net/ipv6/af_inet6.c | 19 +++++-------------- > 4 files changed, 14 insertions(+), 30 deletions(-) > > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c > index 11c4ca1..eedf814 100644 > --- a/net/ipv4/af_inet.c > +++ b/net/ipv4/af_inet.c > @@ -1028,10 +1028,8 @@ static struct inet_protosw inetsw_array[] = > > void inet_register_protosw(struct inet_protosw *p) > { > - struct list_head *lh; > - struct inet_protosw *answer; > + struct inet_protosw *answer, *last_perm; > int protocol = p->protocol; > - struct list_head *last_perm; > > spin_lock_bh(&inetsw_lock); > > @@ -1040,14 +1038,13 @@ void inet_register_protosw(struct inet_protosw *p) > > /* If we are trying to override a permanent protocol, bail. */ > last_perm = &inetsw[p->type]; > - list_for_each(lh, &inetsw[p->type]) { > - answer = list_entry(lh, struct inet_protosw, list); > + list_for_each_entry(answer, &inetsw[p->type], list) { > /* Check only the non-wild match. */ > if ((INET_PROTOSW_PERMANENT & answer->flags) == 0) > break; > if (protocol == answer->protocol) > goto out_permanent; > - last_perm = lh; > + last_perm = answer; > } > > /* Add the new entry after the last permanent entry if any, so that > @@ -1056,7 +1053,7 @@ void inet_register_protosw(struct inet_protosw *p) > * non-permanent entry. This means that when we remove this entry, the > * system automatically returns to the old behavior. > */ > - list_add_rcu(&p->list, last_perm); > + list_add_rcu(&p->list, &last_perm->list); > out: > spin_unlock_bh(&inetsw_lock); > > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c > index a800cee..8810694 100644 > --- a/net/ipv4/tcp_output.c > +++ b/net/ipv4/tcp_output.c > @@ -751,16 +751,14 @@ static void tcp_tasklet_func(unsigned long data) > struct tsq_tasklet *tsq = (struct tsq_tasklet *)data; > LIST_HEAD(list); > unsigned long flags; > - struct list_head *q, *n; > - struct tcp_sock *tp; > + struct tcp_sock *tp, *n; > struct sock *sk; > > local_irq_save(flags); > list_splice_init(&tsq->head, &list); > local_irq_restore(flags); > > - list_for_each_safe(q, n, &list) { > - tp = list_entry(q, struct tcp_sock, tsq_node); > + list_for_each_entry_safe(tp, n, &list, tsq_node) { > list_del(&tp->tsq_node); > > sk = (struct sock *)tp; > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index 7082fb7..e293647 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -865,21 +865,19 @@ void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp) > static void > ipv6_link_dev_addr(struct inet6_dev *idev, struct inet6_ifaddr *ifp) > { > - struct list_head *p; > + struct inet6_ifaddr *ifa; > int ifp_scope = ipv6_addr_src_scope(&ifp->addr); > > /* > * Each device address list is sorted in order of scope - > * global before linklocal. > */ > - list_for_each(p, &idev->addr_list) { > - struct inet6_ifaddr *ifa > - = list_entry(p, struct inet6_ifaddr, if_list); > + list_for_each_entry(ifa, &idev->addr_list, if_list) { > if (ifp_scope >= ipv6_addr_src_scope(&ifa->addr)) > break; > } > > - list_add_tail(&ifp->if_list, p); > + list_add_tail(&ifp->if_list, &ifa->if_list); > } > > static u32 inet6_addr_hash(const struct in6_addr *addr) > diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c > index 8ec0df7..437a500 100644 > --- a/net/ipv6/af_inet6.c > +++ b/net/ipv6/af_inet6.c > @@ -568,9 +568,7 @@ static const struct net_proto_family inet6_family_ops = { > > int inet6_register_protosw(struct inet_protosw *p) > { > - struct list_head *lh; > - struct inet_protosw *answer; > - struct list_head *last_perm; > + struct inet_protosw *answer, *last_perm; > int protocol = p->protocol; > int ret; > > @@ -581,23 +579,16 @@ int inet6_register_protosw(struct inet_protosw *p) > goto out_illegal; > > /* If we are trying to override a permanent protocol, bail. */ > - answer = NULL; > ret = -EPERM; > last_perm = &inetsw6[p->type]; > - list_for_each(lh, &inetsw6[p->type]) { > - answer = list_entry(lh, struct inet_protosw, list); > - > + list_for_each_entry(answer, &inetsw6[p->type], list) { > /* Check only the non-wild match. */ > if (INET_PROTOSW_PERMANENT & answer->flags) { > if (protocol == answer->protocol) > - break; > - last_perm = lh; > + goto out_permanent; > + last_perm = answer; > } > - > - answer = NULL; > } > - if (answer) > - goto out_permanent; > > /* Add the new entry after the last permanent entry if any, so that > * the new entry does not override a permanent entry when matched with > @@ -605,7 +596,7 @@ int inet6_register_protosw(struct inet_protosw *p) > * non-permanent entry. This means that when we remove this entry, the > * system automatically returns to the old behavior. > */ > - list_add_rcu(&p->list, last_perm); > + list_add_rcu(&p->list, &last_perm->list); > ret = 0; > out: > spin_unlock_bh(&inetsw6_lock); > -- > 2.5.0 > > > -- 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/