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Commit eaa72dc4 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

neigh: increase queue_len_bytes to match wmem_default 



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: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0dd5759d

Documentation/networking/ip-sysctl.txt

+5 −2
Original line number Diff line number Diff line
@@ -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.

include/net/sock.h

+10 −0
Original line number Diff line number Diff line
@@ -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;

net/core/sock.c

+0 −10
Original line number Diff line number Diff line
@@ -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);

net/decnet/dn_neigh.c

+1 −1
Original line number Diff line number Diff line
@@ -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,

net/ipv4/arp.c

+1 −1
Original line number Diff line number Diff line
@@ -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,