| Message ID | 20201102174756.6933-1-jdike@akamai.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] Exempt multicast addresses from five-second neighbor lifetime | expand |
Hi Jeff,
I love your patch! Perhaps something to improve:
[auto build test WARNING on net-next/master]
url: https://github.com/0day-ci/linux/commits/Jeff-Dike/Exempt-multicast-addresses-from-five-second-neighbor-lifetime/20201103-015012
base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git c43fd36f7fec6c227c5e8a8ddd7d3fe97472182f
config: i386-randconfig-s002-20201102 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
# apt-get install sparse
# sparse version: v0.6.3-56-gc09e8239-dirty
# https://github.com/0day-ci/linux/commit/e4ca67984d1bb7e5276cf18921c75dcd05ce0275
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Jeff-Dike/Exempt-multicast-addresses-from-five-second-neighbor-lifetime/20201103-015012
git checkout e4ca67984d1bb7e5276cf18921c75dcd05ce0275
# save the attached .config to linux build tree
make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
"sparse warnings: (new ones prefixed by >>)"
net/ipv4/arp.c:933:9: sparse: sparse: preprocessor token IN_MULTICAST redefined
net/ipv4/arp.c: note: in included file (through include/linux/in.h):
>> include/uapi/linux/in.h:273:9: sparse: this was the original definition
>> net/ipv4/arp.c:937:16: sparse: sparse: cast from restricted __be32
vim +937 net/ipv4/arp.c
932
> 933 #define IN_MULTICAST(a) ((((long)(a)) & 0xf0000000) == 0xe0000000)
934
935 static int arp_is_multicast(const void *pkey)
936 {
> 937 return IN_MULTICAST(htonl(*((u32 *)pkey)));
938 }
939
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Hi Jeff,
I love your patch! Perhaps something to improve:
[auto build test WARNING on net-next/master]
url: https://github.com/0day-ci/linux/commits/Jeff-Dike/Exempt-multicast-addresses-from-five-second-neighbor-lifetime/20201103-015012
base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git c43fd36f7fec6c227c5e8a8ddd7d3fe97472182f
config: powerpc64-randconfig-r001-20201102 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project cc91554ebb66e8c9a4b8c67ca2f1343eaac10cf6)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install powerpc64 cross compiling tool for clang build
# apt-get install binutils-powerpc64-linux-gnu
# https://github.com/0day-ci/linux/commit/e4ca67984d1bb7e5276cf18921c75dcd05ce0275
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Jeff-Dike/Exempt-multicast-addresses-from-five-second-neighbor-lifetime/20201103-015012
git checkout e4ca67984d1bb7e5276cf18921c75dcd05ce0275
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> net/ipv4/arp.c:933:9: warning: 'IN_MULTICAST' macro redefined [-Wmacro-redefined]
#define IN_MULTICAST(a) ((((long)(a)) & 0xf0000000) == 0xe0000000)
^
include/uapi/linux/in.h:273:9: note: previous definition is here
#define IN_MULTICAST(a) IN_CLASSD(a)
^
1 warning generated.
vim +/IN_MULTICAST +933 net/ipv4/arp.c
932
> 933 #define IN_MULTICAST(a) ((((long)(a)) & 0xf0000000) == 0xe0000000)
934
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff --git a/include/net/neighbour.h b/include/net/neighbour.h index 81ee17594c32..22ced1381ede 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -204,6 +204,7 @@ struct neigh_table { int (*pconstructor)(struct pneigh_entry *); void (*pdestructor)(struct pneigh_entry *); void (*proxy_redo)(struct sk_buff *skb); + int (*is_multicast)(const void *pkey); bool (*allow_add)(const struct net_device *dev, struct netlink_ext_ack *extack); char *id; diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 8e39e28b0a8d..9500d28a43b0 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -235,6 +235,8 @@ static int neigh_forced_gc(struct neigh_table *tbl) write_lock(&n->lock); if ((n->nud_state == NUD_FAILED) || + (tbl->is_multicast && + tbl->is_multicast(n->primary_key)) || time_after(tref, n->updated)) remove = true; write_unlock(&n->lock); diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 687971d83b4e..1032ad76a3f5 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -125,6 +125,7 @@ static int arp_constructor(struct neighbour *neigh); static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb); static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb); static void parp_redo(struct sk_buff *skb); +static int arp_is_multicast(const void *pkey); static const struct neigh_ops arp_generic_ops = { .family = AF_INET, @@ -156,6 +157,7 @@ struct neigh_table arp_tbl = { .key_eq = arp_key_eq, .constructor = arp_constructor, .proxy_redo = parp_redo, + .is_multicast = arp_is_multicast, .id = "arp_cache", .parms = { .tbl = &arp_tbl, @@ -928,6 +930,12 @@ static void parp_redo(struct sk_buff *skb) arp_process(dev_net(skb->dev), NULL, skb); } +#define IN_MULTICAST(a) ((((long)(a)) & 0xf0000000) == 0xe0000000) + +static int arp_is_multicast(const void *pkey) +{ + return IN_MULTICAST(htonl(*((u32 *)pkey))); +} /* * Receive an arp request from the device layer. diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 27f29b957ee7..6aed5536fc5c 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -81,6 +81,7 @@ static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb); static int pndisc_constructor(struct pneigh_entry *n); static void pndisc_destructor(struct pneigh_entry *n); static void pndisc_redo(struct sk_buff *skb); +static int ndisc_is_multicast(const void *pkey); static const struct neigh_ops ndisc_generic_ops = { .family = AF_INET6, @@ -115,6 +116,7 @@ struct neigh_table nd_tbl = { .pconstructor = pndisc_constructor, .pdestructor = pndisc_destructor, .proxy_redo = pndisc_redo, + .is_multicast = ndisc_is_multicast, .allow_add = ndisc_allow_add, .id = "ndisc_cache", .parms = { @@ -1706,6 +1708,11 @@ static void pndisc_redo(struct sk_buff *skb) kfree_skb(skb); } +static int ndisc_is_multicast(const void *pkey) +{ + return (((struct in6_addr *)pkey)->in6_u.u6_addr8[0] & 0xf0) == 0xf0; +} + static bool ndisc_suppress_frag_ndisc(struct sk_buff *skb) { struct inet6_dev *idev = __in6_dev_get(skb->dev);
Commit 58956317c8de ("neighbor: Improve garbage collection") guarantees neighbour table entries a five-second lifetime. Processes which make heavy use of multicast can fill the neighour table with multicast addresses in five seconds. At that point, neighbour entries can't be GC-ed because they aren't five seconds old yet, the kernel log starts to fill up with "neighbor table overflow!" messages, and sends start to fail. This patch allows multicast addresses to be thrown out before they've lived out their five seconds. This makes room for non-multicast addresses and makes messages to all addresses more reliable in these circumstances. Signed-off-by: Jeff Dike <jdike@akamai.com> --- include/net/neighbour.h | 1 + net/core/neighbour.c | 2 ++ net/ipv4/arp.c | 8 ++++++++ net/ipv6/ndisc.c | 7 +++++++ 4 files changed, 18 insertions(+)