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SubjectRe: [PATCH] list_for_each_rcu must die: networking
Paul E. McKenney wrote:
> All uses of list_for_each_rcu() can be profitably replaced by the
> easier-to-use list_for_each_entry_rcu(). This patch makes this change
> for networking, in preparation for removing the list_for_each_rcu()
> API entirely.
>
> Updated to remove the two now-unused variables as noted by Dave Miller,
> and also to fix my bonehead error detected by Kamalesh Babulal and
> Alexey Dobriyan. It now passes LTP on POWER. And also has valid SOB.
> Some days it just doesn't pay to get out of bed...

Hi Paul,

Thanks, the patch fixes the oops.

Tested-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
> Acked-by: David S. Miller <davem@davemloft.net> (lkml.org/lkml/2008/4/23/448)
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
>
> 802/psnap.c | 4 +---
> ipv4/af_inet.c | 9 +++------
> ipv6/af_inet6.c | 9 +++------
> 3 files changed, 7 insertions(+), 15 deletions(-)
>
> diff -urpNa -X dontdiff linux-2.6.26-rc2/net/802/psnap.c linux-2.6.26-rc2-lfer-net/net/802/psnap.c
> --- linux-2.6.26-rc2/net/802/psnap.c 2008-04-16 19:49:44.000000000 -0700
> +++ linux-2.6.26-rc2-lfer-net/net/802/psnap.c 2008-05-14 13:38:13.000000000 -0700
> @@ -30,11 +30,9 @@ static struct llc_sap *snap_sap;
> */
> static struct datalink_proto *find_snap_client(unsigned char *desc)
> {
> - struct list_head *entry;
> struct datalink_proto *proto = NULL, *p;
>
> - list_for_each_rcu(entry, &snap_list) {
> - p = list_entry(entry, struct datalink_proto, node);
> + list_for_each_entry_rcu(p, &snap_list, node) {
> if (!memcmp(p->type, desc, 5)) {
> proto = p;
> break;
> diff -urpNa -X dontdiff linux-2.6.26-rc2/net/ipv4/af_inet.c linux-2.6.26-rc2-lfer-net/net/ipv4/af_inet.c
> --- linux-2.6.26-rc2/net/ipv4/af_inet.c 2008-05-14 13:35:32.000000000 -0700
> +++ linux-2.6.26-rc2-lfer-net/net/ipv4/af_inet.c 2008-05-14 13:46:26.000000000 -0700
> @@ -267,7 +267,6 @@ static inline int inet_netns_ok(struct n
> static int inet_create(struct net *net, struct socket *sock, int protocol)
> {
> struct sock *sk;
> - struct list_head *p;
> struct inet_protosw *answer;
> struct inet_sock *inet;
> struct proto *answer_prot;
> @@ -284,13 +283,12 @@ static int inet_create(struct net *net,
> sock->state = SS_UNCONNECTED;
>
> /* Look for the requested type/protocol pair. */
> - answer = NULL;
> lookup_protocol:
> err = -ESOCKTNOSUPPORT;
> rcu_read_lock();
> - list_for_each_rcu(p, &inetsw[sock->type]) {
> - answer = list_entry(p, struct inet_protosw, list);
> + list_for_each_entry_rcu(answer, &inetsw[sock->type], list) {
>
> + err = 0;
> /* Check the non-wild match. */
> if (protocol == answer->protocol) {
> if (protocol != IPPROTO_IP)
> @@ -305,10 +303,9 @@ lookup_protocol:
> break;
> }
> err = -EPROTONOSUPPORT;
> - answer = NULL;
> }
>
> - if (unlikely(answer == NULL)) {
> + if (unlikely(err)) {
> if (try_loading_module < 2) {
> rcu_read_unlock();
> /*
> diff -urpNa -X dontdiff linux-2.6.26-rc2/net/ipv6/af_inet6.c linux-2.6.26-rc2-lfer-net/net/ipv6/af_inet6.c
> --- linux-2.6.26-rc2/net/ipv6/af_inet6.c 2008-05-14 13:35:32.000000000 -0700
> +++ linux-2.6.26-rc2-lfer-net/net/ipv6/af_inet6.c 2008-05-14 13:45:08.000000000 -0700
> @@ -87,7 +87,6 @@ static int inet6_create(struct net *net,
> struct inet_sock *inet;
> struct ipv6_pinfo *np;
> struct sock *sk;
> - struct list_head *p;
> struct inet_protosw *answer;
> struct proto *answer_prot;
> unsigned char answer_flags;
> @@ -101,13 +100,12 @@ static int inet6_create(struct net *net,
> build_ehash_secret();
>
> /* Look for the requested type/protocol pair. */
> - answer = NULL;
> lookup_protocol:
> err = -ESOCKTNOSUPPORT;
> rcu_read_lock();
> - list_for_each_rcu(p, &inetsw6[sock->type]) {
> - answer = list_entry(p, struct inet_protosw, list);
> + list_for_each_entry_rcu(answer, &inetsw6[sock->type], list) {
>
> + err = 0;
> /* Check the non-wild match. */
> if (protocol == answer->protocol) {
> if (protocol != IPPROTO_IP)
> @@ -122,10 +120,9 @@ lookup_protocol:
> break;
> }
> err = -EPROTONOSUPPORT;
> - answer = NULL;
> }
>
> - if (!answer) {
> + if (err) {
> if (try_loading_module < 2) {
> rcu_read_unlock();
> /*
> --

--
Thanks & Regards,
Kamalesh Babulal,
Linux Technology Center,
IBM, ISTL.


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