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Miller" , Manoj Boopathi Raj Subject: Re: [PATCH 4.4 002/193] net: replace dst_cache ip6_tunnel implementation with the generic one Message-ID: <20180224153711.GA4657@flashbox> References: <20180223170325.997716448@linuxfoundation.org> <20180223170326.406395326@linuxfoundation.org> <20180223230008.GA30215@flashbox> <20180224083539.GE9681@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180224083539.GE9681@kroah.com> User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 24, 2018 at 09:35:39AM +0100, Greg Kroah-Hartman wrote: > On Fri, Feb 23, 2018 at 04:00:08PM -0700, Nathan Chancellor wrote: > > On Fri, Feb 23, 2018 at 07:23:55PM +0100, Greg Kroah-Hartman wrote: > > > 4.4-stable review patch. If anyone has any objections, please let me know. > > > > > > ------------------ > > > > > > From: Paolo Abeni > > > > > > commit 607f725f6f7d5ec3759fbc16224afb60e2152a5b upstream. > > > > > > This also fix a potential race into the existing tunnel code, which > > > could lead to the wrong dst to be permanenty cached: > > > > > > CPU1: CPU2: > > > > > > > > > dst = ip6_route_output(...) > > > > > > dst_cache_reset() // no effect, > > > // the cache is empty > > > dst_cache_set() // the wrong dst > > > // is permanenty stored > > > // into the cache > > > > > > With the new dst implementation the above race is not possible > > > since the first cache lookup after dst_cache_reset will fail due > > > to the timestamp check > > > > > > Signed-off-by: Paolo Abeni > > > Suggested-and-acked-by: Hannes Frederic Sowa > > > Signed-off-by: David S. Miller > > > Signed-off-by: Manoj Boopathi Raj > > > Signed-off-by: Greg Kroah-Hartman > > > > > > --- > > > include/net/ip6_tunnel.h | 15 ---- > > > net/ipv6/Kconfig | 1 > > > net/ipv6/ip6_gre.c | 12 +-- > > > net/ipv6/ip6_tunnel.c | 151 +++++++---------------------------------------- > > > net/ipv6/ip6_vti.c | 2 > > > 5 files changed, 35 insertions(+), 146 deletions(-) > > > > > > --- a/include/net/ip6_tunnel.h > > > +++ b/include/net/ip6_tunnel.h > > > @@ -5,6 +5,8 @@ > > > #include > > > #include > > > #include > > > +#include > > > +#include > > > > > > #define IP6TUNNEL_ERR_TIMEO (30*HZ) > > > > > > @@ -32,12 +34,6 @@ struct __ip6_tnl_parm { > > > __be32 o_key; > > > }; > > > > > > -struct ip6_tnl_dst { > > > - seqlock_t lock; > > > - struct dst_entry __rcu *dst; > > > - u32 cookie; > > > -}; > > > - > > > /* IPv6 tunnel */ > > > struct ip6_tnl { > > > struct ip6_tnl __rcu *next; /* next tunnel in list */ > > > @@ -45,7 +41,7 @@ struct ip6_tnl { > > > struct net *net; /* netns for packet i/o */ > > > struct __ip6_tnl_parm parms; /* tunnel configuration parameters */ > > > struct flowi fl; /* flowi template for xmit */ > > > - struct ip6_tnl_dst __percpu *dst_cache; /* cached dst */ > > > + struct dst_cache dst_cache; /* cached dst */ > > > > > > int err_count; > > > unsigned long err_time; > > > @@ -65,11 +61,6 @@ struct ipv6_tlv_tnl_enc_lim { > > > __u8 encap_limit; /* tunnel encapsulation limit */ > > > } __packed; > > > > > > -struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t); > > > -int ip6_tnl_dst_init(struct ip6_tnl *t); > > > -void ip6_tnl_dst_destroy(struct ip6_tnl *t); > > > -void ip6_tnl_dst_reset(struct ip6_tnl *t); > > > -void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst); > > > int ip6_tnl_rcv_ctl(struct ip6_tnl *t, const struct in6_addr *laddr, > > > const struct in6_addr *raddr); > > > int ip6_tnl_xmit_ctl(struct ip6_tnl *t, const struct in6_addr *laddr, > > > --- a/net/ipv6/Kconfig > > > +++ b/net/ipv6/Kconfig > > > @@ -205,6 +205,7 @@ config IPV6_NDISC_NODETYPE > > > config IPV6_TUNNEL > > > tristate "IPv6: IP-in-IPv6 tunnel (RFC2473)" > > > select INET6_TUNNEL > > > + select DST_CACHE > > > ---help--- > > > Support for IPv6-in-IPv6 and IPv4-in-IPv6 tunnels described in > > > RFC 2473. > > > --- a/net/ipv6/ip6_gre.c > > > +++ b/net/ipv6/ip6_gre.c > > > @@ -362,7 +362,7 @@ static void ip6gre_tunnel_uninit(struct > > > struct ip6gre_net *ign = net_generic(t->net, ip6gre_net_id); > > > > > > ip6gre_tunnel_unlink(ign, t); > > > - ip6_tnl_dst_reset(t); > > > + dst_cache_reset(&t->dst_cache); > > > dev_put(dev); > > > } > > > > > > @@ -640,7 +640,7 @@ static netdev_tx_t ip6gre_xmit2(struct s > > > } > > > > > > if (!fl6->flowi6_mark) > > > - dst = ip6_tnl_dst_get(tunnel); > > > + dst = dst_cache_get(&tunnel->dst_cache); > > > > > > if (!dst) { > > > dst = ip6_route_output(net, NULL, fl6); > > > @@ -709,7 +709,7 @@ static netdev_tx_t ip6gre_xmit2(struct s > > > } > > > > > > if (!fl6->flowi6_mark && ndst) > > > - ip6_tnl_dst_set(tunnel, ndst); > > > + dst_cache_set_ip6(&tunnel->dst_cache, ndst, &fl6->saddr); > > > skb_dst_set(skb, dst); > > > > > > proto = NEXTHDR_GRE; > > > @@ -1017,7 +1017,7 @@ static int ip6gre_tnl_change(struct ip6_ > > > t->parms.o_key = p->o_key; > > > t->parms.i_flags = p->i_flags; > > > t->parms.o_flags = p->o_flags; > > > - ip6_tnl_dst_reset(t); > > > + dst_cache_reset(&t->dst_cache); > > > ip6gre_tnl_link_config(t, set_mtu); > > > return 0; > > > } > > > @@ -1228,7 +1228,7 @@ static void ip6gre_dev_free(struct net_d > > > { > > > struct ip6_tnl *t = netdev_priv(dev); > > > > > > - ip6_tnl_dst_destroy(t); > > > + dst_cache_destroy(&t->dst_cache); > > > free_percpu(dev->tstats); > > > free_netdev(dev); > > > } > > > @@ -1266,7 +1266,7 @@ static int ip6gre_tunnel_init_common(str > > > if (!dev->tstats) > > > return -ENOMEM; > > > > > > - ret = ip6_tnl_dst_init(tunnel); > > > + ret = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL); > > > if (ret) { > > > free_percpu(dev->tstats); > > > dev->tstats = NULL; > > > --- a/net/ipv6/ip6_tunnel.c > > > +++ b/net/ipv6/ip6_tunnel.c > > > @@ -122,97 +122,6 @@ static struct net_device_stats *ip6_get_ > > > return &dev->stats; > > > } > > > > > > -/* > > > - * Locking : hash tables are protected by RCU and RTNL > > > - */ > > > - > > > -static void ip6_tnl_per_cpu_dst_set(struct ip6_tnl_dst *idst, > > > - struct dst_entry *dst) > > > -{ > > > - write_seqlock_bh(&idst->lock); > > > - dst_release(rcu_dereference_protected( > > > - idst->dst, > > > - lockdep_is_held(&idst->lock.lock))); > > > - if (dst) { > > > - dst_hold(dst); > > > - idst->cookie = rt6_get_cookie((struct rt6_info *)dst); > > > - } else { > > > - idst->cookie = 0; > > > - } > > > - rcu_assign_pointer(idst->dst, dst); > > > - write_sequnlock_bh(&idst->lock); > > > -} > > > - > > > -struct dst_entry *ip6_tnl_dst_get(struct ip6_tnl *t) > > > -{ > > > - struct ip6_tnl_dst *idst; > > > - struct dst_entry *dst; > > > - unsigned int seq; > > > - u32 cookie; > > > - > > > - idst = raw_cpu_ptr(t->dst_cache); > > > - > > > - rcu_read_lock(); > > > - do { > > > - seq = read_seqbegin(&idst->lock); > > > - dst = rcu_dereference(idst->dst); > > > - cookie = idst->cookie; > > > - } while (read_seqretry(&idst->lock, seq)); > > > - > > > - if (dst && !atomic_inc_not_zero(&dst->__refcnt)) > > > - dst = NULL; > > > - rcu_read_unlock(); > > > - > > > - if (dst && dst->obsolete && !dst->ops->check(dst, cookie)) { > > > - ip6_tnl_per_cpu_dst_set(idst, NULL); > > > - dst_release(dst); > > > - dst = NULL; > > > - } > > > - return dst; > > > -} > > > -EXPORT_SYMBOL_GPL(ip6_tnl_dst_get); > > > - > > > -void ip6_tnl_dst_reset(struct ip6_tnl *t) > > > -{ > > > - int i; > > > - > > > - for_each_possible_cpu(i) > > > - ip6_tnl_per_cpu_dst_set(per_cpu_ptr(t->dst_cache, i), NULL); > > > -} > > > -EXPORT_SYMBOL_GPL(ip6_tnl_dst_reset); > > > - > > > -void ip6_tnl_dst_set(struct ip6_tnl *t, struct dst_entry *dst) > > > -{ > > > - ip6_tnl_per_cpu_dst_set(raw_cpu_ptr(t->dst_cache), dst); > > > - > > > -} > > > -EXPORT_SYMBOL_GPL(ip6_tnl_dst_set); > > > - > > > -void ip6_tnl_dst_destroy(struct ip6_tnl *t) > > > -{ > > > - if (!t->dst_cache) > > > - return; > > > - > > > - ip6_tnl_dst_reset(t); > > > - free_percpu(t->dst_cache); > > > -} > > > -EXPORT_SYMBOL_GPL(ip6_tnl_dst_destroy); > > > - > > > -int ip6_tnl_dst_init(struct ip6_tnl *t) > > > -{ > > > - int i; > > > - > > > - t->dst_cache = alloc_percpu(struct ip6_tnl_dst); > > > - if (!t->dst_cache) > > > - return -ENOMEM; > > > - > > > - for_each_possible_cpu(i) > > > - seqlock_init(&per_cpu_ptr(t->dst_cache, i)->lock); > > > - > > > - return 0; > > > -} > > > -EXPORT_SYMBOL_GPL(ip6_tnl_dst_init); > > > - > > > /** > > > * ip6_tnl_lookup - fetch tunnel matching the end-point addresses > > > * @remote: the address of the tunnel exit-point > > > @@ -331,7 +240,7 @@ static void ip6_dev_free(struct net_devi > > > { > > > struct ip6_tnl *t = netdev_priv(dev); > > > > > > - ip6_tnl_dst_destroy(t); > > > + dst_cache_destroy(&t->dst_cache); > > > free_percpu(dev->tstats); > > > free_netdev(dev); > > > } > > > @@ -464,7 +373,7 @@ ip6_tnl_dev_uninit(struct net_device *de > > > RCU_INIT_POINTER(ip6n->tnls_wc[0], NULL); > > > else > > > ip6_tnl_unlink(ip6n, t); > > > - ip6_tnl_dst_reset(t); > > > + dst_cache_reset(&t->dst_cache); > > > dev_put(dev); > > > } > > > > > > @@ -1053,7 +962,6 @@ static int ip6_tnl_xmit2(struct sk_buff > > > struct ipv6_tel_txoption opt; > > > struct dst_entry *dst = NULL, *ndst = NULL; > > > struct net_device *tdev; > > > - bool use_cache = false; > > > int mtu; > > > unsigned int max_headroom = sizeof(struct ipv6hdr); > > > u8 proto; > > > @@ -1061,39 +969,28 @@ static int ip6_tnl_xmit2(struct sk_buff > > > > > > /* NBMA tunnel */ > > > if (ipv6_addr_any(&t->parms.raddr)) { > > > - if (skb->protocol == htons(ETH_P_IPV6)) { > > > - struct in6_addr *addr6; > > > - struct neighbour *neigh; > > > - int addr_type; > > > - > > > - if (!skb_dst(skb)) > > > - goto tx_err_link_failure; > > > - > > > - neigh = dst_neigh_lookup(skb_dst(skb), > > > - &ipv6_hdr(skb)->daddr); > > > - if (!neigh) > > > - goto tx_err_link_failure; > > > + struct in6_addr *addr6; > > > + struct neighbour *neigh; > > > + int addr_type; > > > + > > > + if (!skb_dst(skb)) > > > + goto tx_err_link_failure; > > > > > > - addr6 = (struct in6_addr *)&neigh->primary_key; > > > - addr_type = ipv6_addr_type(addr6); > > > + neigh = dst_neigh_lookup(skb_dst(skb), > > > + &ipv6_hdr(skb)->daddr); > > > + if (!neigh) > > > + goto tx_err_link_failure; > > > > > > - if (addr_type == IPV6_ADDR_ANY) > > > - addr6 = &ipv6_hdr(skb)->daddr; > > > + addr6 = (struct in6_addr *)&neigh->primary_key; > > > + addr_type = ipv6_addr_type(addr6); > > > > > > - memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); > > > - neigh_release(neigh); > > > - } > > > - } else if (t->parms.proto != 0 && !(t->parms.flags & > > > - (IP6_TNL_F_USE_ORIG_TCLASS | > > > - IP6_TNL_F_USE_ORIG_FWMARK))) { > > > - /* enable the cache only if neither the outer protocol nor the > > > - * routing decision depends on the current inner header value > > > - */ > > > - use_cache = true; > > > - } > > > + if (addr_type == IPV6_ADDR_ANY) > > > + addr6 = &ipv6_hdr(skb)->daddr; > > > > > > - if (use_cache) > > > - dst = ip6_tnl_dst_get(t); > > > + memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr)); > > > + neigh_release(neigh); > > > + } else if (!fl6->flowi6_mark) > > > + dst = dst_cache_get(&t->dst_cache); > > > > > > if (!ip6_tnl_xmit_ctl(t, &fl6->saddr, &fl6->daddr)) > > > goto tx_err_link_failure; > > > @@ -1156,8 +1053,8 @@ static int ip6_tnl_xmit2(struct sk_buff > > > skb = new_skb; > > > } > > > > > > - if (use_cache && ndst) > > > - ip6_tnl_dst_set(t, ndst); > > > + if (!fl6->flowi6_mark && ndst) > > > + dst_cache_set_ip6(&t->dst_cache, ndst, &fl6->saddr); > > > skb_dst_set(skb, dst); > > > > > > skb->transport_header = skb->network_header; > > > @@ -1392,7 +1289,7 @@ ip6_tnl_change(struct ip6_tnl *t, const > > > t->parms.flowinfo = p->flowinfo; > > > t->parms.link = p->link; > > > t->parms.proto = p->proto; > > > - ip6_tnl_dst_reset(t); > > > + dst_cache_reset(&t->dst_cache); > > > ip6_tnl_link_config(t); > > > return 0; > > > } > > > @@ -1663,7 +1560,7 @@ ip6_tnl_dev_init_gen(struct net_device * > > > if (!dev->tstats) > > > return -ENOMEM; > > > > > > - ret = ip6_tnl_dst_init(t); > > > + ret = dst_cache_init(&t->dst_cache, GFP_KERNEL); > > > if (ret) { > > > free_percpu(dev->tstats); > > > dev->tstats = NULL; > > > --- a/net/ipv6/ip6_vti.c > > > +++ b/net/ipv6/ip6_vti.c > > > @@ -645,7 +645,7 @@ vti6_tnl_change(struct ip6_tnl *t, const > > > t->parms.i_key = p->i_key; > > > t->parms.o_key = p->o_key; > > > t->parms.proto = p->proto; > > > - ip6_tnl_dst_reset(t); > > > + dst_cache_reset(&t->dst_cache); > > > vti6_link_config(t); > > > return 0; > > > } > > > > > > > > > > It may also be wise to take these two commits from mainline, as they > > are along the same lines as this one: > > > > 09acddf873b ("ip_tunnel: replace dst_cache with generic implementation") > > 27337e16f2d ("ip_tunnel: fix preempt warning in ip tunnel creation/updating") > > Ah, good idea. > > > There is a minor conflict with the first one due to stable commit > > 6f99825e7632 ("sit: fix a double free on error path"). > > > > I'll most likely carry them anyways, it fixes a build error with some > > out of tree code but less out of tree code I have, the better! > > I'll do that for the next release. What "out of tree" code relies on > this? Something from the CAF tree that is not merged upstream? > > thanks, > > greg k-h WireGuard. For any tree that didn't have dst_cache, it was backported and used automatically but if dst_cache is present, it was implicitly relying on DST_CACHE being selected through NET_UDP_TUNNEL (which is how I found those commits). Jason has since fixed it: https://git.zx2c4.com/WireGuard/commit/?id=b3722a8b0578630794776ece5710e6a47155aa92 I'd still say those commits are worth adding since they are part of that series. Thanks! Nathan