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neigh: increase queue_len_bytes to match wmem_default

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Florian reported UDP xmit drops that could be root caused to the
too small neigh limit.

Current limit is 64 KB, meaning that even a single UDP socket would hit
it, since its default sk_sndbuf comes from net.core.wmem_default
(~212992 bytes on 64bit arches).

Once ARP/ND resolution is in progress, we should allow a little more
packets to be queued, at least for one producer.

Once neigh arp_queue is filled, a rogue socket should hit its sk_sndbuf
limit and either block in sendmsg() or return -EAGAIN.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-08-29 15:16:01 -07:00 committed by David S. Miller
parent 0dd5759dbb
commit eaa72dc474
7 changed files with 19 additions and 16 deletions
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7
Documentation/networking/ip-sysctl.txt
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@ -109,7 +109,10 @@ neigh/default/unres_qlen_bytes - INTEGER
queued for each unresolved address by other network layers.
(added in linux 3.3)
Setting negative value is meaningless and will return error.
Default: 65536 Bytes(64KB)
Default: SK_WMEM_MAX, (same as net.core.wmem_default).
Exact value depends on architecture and kernel options,
but should be enough to allow queuing 256 packets
of medium size.
neigh/default/unres_qlen - INTEGER
The maximum number of packets which may be queued for each
@ -119,7 +122,7 @@ neigh/default/unres_qlen - INTEGER
unexpected packet loss. The current default value is calculated
according to default value of unres_qlen_bytes and true size of
packet.
Default: 31
Default: 101
mtu_expires - INTEGER
Time, in seconds, that cached PMTU information is kept.

10
include/net/sock.h
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@ -2368,6 +2368,16 @@ bool sk_net_capable(const struct sock *sk, int cap);
void sk_get_meminfo(const struct sock *sk, u32 *meminfo);
/* Take into consideration the size of the struct sk_buff overhead in the
* determination of these values, since that is non-constant across
* platforms. This makes socket queueing behavior and performance
* not depend upon such differences.
*/
#define _SK_MEM_PACKETS 256
#define _SK_MEM_OVERHEAD SKB_TRUESIZE(256)
#define SK_WMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
#define SK_RMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
extern __u32 sysctl_wmem_max;
extern __u32 sysctl_rmem_max;

10
net/core/sock.c
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@ -307,16 +307,6 @@ static struct lock_class_key af_wlock_keys[AF_MAX];
static struct lock_class_key af_elock_keys[AF_MAX];
static struct lock_class_key af_kern_callback_keys[AF_MAX];
/* Take into consideration the size of the struct sk_buff overhead in the
* determination of these values, since that is non-constant across
* platforms. This makes socket queueing behavior and performance
* not depend upon such differences.
*/
#define _SK_MEM_PACKETS 256
#define _SK_MEM_OVERHEAD SKB_TRUESIZE(256)
#define SK_WMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
#define SK_RMEM_MAX (_SK_MEM_OVERHEAD * _SK_MEM_PACKETS)
/* Run time adjustable parameters. */
__u32 sysctl_wmem_max __read_mostly = SK_WMEM_MAX;
EXPORT_SYMBOL(sysctl_wmem_max);

2
net/decnet/dn_neigh.c
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@ -94,7 +94,7 @@ struct neigh_table dn_neigh_table = {
[NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
[NEIGH_VAR_QUEUE_LEN_BYTES] = 64*1024,
[NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
[NEIGH_VAR_PROXY_QLEN] = 0,
[NEIGH_VAR_ANYCAST_DELAY] = 0,
[NEIGH_VAR_PROXY_DELAY] = 0,

2
net/ipv4/arp.c
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@ -171,7 +171,7 @@ struct neigh_table arp_tbl = {
[NEIGH_VAR_BASE_REACHABLE_TIME] = 30 * HZ,
[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
[NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
[NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
[NEIGH_VAR_PROXY_QLEN] = 64,
[NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
[NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,

2
net/ipv4/tcp_input.c
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@ -6086,9 +6086,9 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
struct tcp_sock *tp = tcp_sk(sk);
struct net *net = sock_net(sk);
struct sock *fastopen_sk = NULL;
struct dst_entry *dst = NULL;
struct request_sock *req;
bool want_cookie = false;
struct dst_entry *dst;
struct flowi fl;
/* TW buckets are converted to open requests without

2
net/ipv6/ndisc.c
View File

@ -127,7 +127,7 @@ struct neigh_table nd_tbl = {
[NEIGH_VAR_BASE_REACHABLE_TIME] = ND_REACHABLE_TIME,
[NEIGH_VAR_DELAY_PROBE_TIME] = 5 * HZ,
[NEIGH_VAR_GC_STALETIME] = 60 * HZ,
[NEIGH_VAR_QUEUE_LEN_BYTES] = 64 * 1024,
[NEIGH_VAR_QUEUE_LEN_BYTES] = SK_WMEM_MAX,
[NEIGH_VAR_PROXY_QLEN] = 64,
[NEIGH_VAR_ANYCAST_DELAY] = 1 * HZ,
[NEIGH_VAR_PROXY_DELAY] = (8 * HZ) / 10,