This patch added /proc/sys/net/ipv4/udp_rmem_min and
/proc/sys/net/ipv4/udp_rmem_min. Each UDP packet is drooped when the
number of pages for socket buffer is beyond the limit and the socket
already consumes minimum buffer.

Cc: Satoshi Oshima <[EMAIL PROTECTED]>
signed-off-by: Hideo Aoki <[EMAIL PROTECTED]>
---

 Documentation/networking/ip-sysctl.txt |   12 ++++++++++++
 include/net/udp.h                      |    4 ++++
 net/ipv4/ip_output.c                   |    4 +++-
 net/ipv4/sysctl_net_ipv4.c             |   20 ++++++++++++++++++++
 net/ipv4/udp.c                         |   13 +++++++++++--
 5 files changed, 50 insertions(+), 3 deletions(-)

diff -pruN net-2.6-udp-p4/Documentation/networking/ip-sysctl.txt 
net-2.6-udp-p5/Documentation/networking/ip-sysctl.txt
--- net-2.6-udp-p4/Documentation/networking/ip-sysctl.txt       2007-11-15 
14:44:21.000000000 -0500
+++ net-2.6-udp-p5/Documentation/networking/ip-sysctl.txt       2007-11-15 
14:44:23.000000000 -0500
@@ -452,6 +452,18 @@ udp_mem - INTEGER
        Number of pages allowed for queueing by all UDP sockets.
        Default is calculated at boot time from amount of available memory.

+udp_rmem_min - INTEGER
+       Minimal size of receive buffer used by UDP sockets. Each UDP socket
+       is able to use the size for receiving data, even if total pages of UDP
+       sockets exceed udp_mem. The unit is byte.
+       Default: 4096
+
+udp_wmem_min - INTEGER
+       Minimal size of send buffer used by UDP sockets. Each UDP socket is
+       able to use the size for sending data, even if total pages of UDP
+       sockets exceed udp_mem. The unit is byte.
+       Default: 4096
+
 CIPSOv4 Variables:

 cipso_cache_enable - BOOLEAN
diff -pruN net-2.6-udp-p4/include/net/udp.h net-2.6-udp-p5/include/net/udp.h
--- net-2.6-udp-p4/include/net/udp.h    2007-11-15 14:44:21.000000000 -0500
+++ net-2.6-udp-p5/include/net/udp.h    2007-11-15 14:44:23.000000000 -0500
@@ -66,7 +66,11 @@ extern rwlock_t udp_hash_lock;
 extern struct proto udp_prot;

 extern atomic_t udp_memory_allocated;
+
+/* sysctl variables for udp */
 extern int sysctl_udp_mem;
+extern int sysctl_udp_rmem_min;
+extern int sysctl_udp_wmem_min;

 struct sk_buff;

diff -pruN net-2.6-udp-p4/net/ipv4/ip_output.c 
net-2.6-udp-p5/net/ipv4/ip_output.c
--- net-2.6-udp-p4/net/ipv4/ip_output.c 2007-11-15 14:44:21.000000000 -0500
+++ net-2.6-udp-p5/net/ipv4/ip_output.c 2007-11-15 14:44:23.000000000 -0500
@@ -705,7 +705,9 @@ static inline int __ip_check_max_skb_pag
        switch(sk->sk_protocol) {
        case IPPROTO_UDP:
                if (atomic_read(sk->sk_prot->memory_allocated) + size
-                   > sk->sk_prot->sysctl_mem[0])
+                   > sk->sk_prot->sysctl_mem[0] &&
+                   atomic_read(&sk->sk_wmem_alloc) + size
+                   > sk->sk_prot->sysctl_wmem[0])
                        return -ENOBUFS;
                /* Fall through */      
        default:
diff -pruN net-2.6-udp-p4/net/ipv4/sysctl_net_ipv4.c 
net-2.6-udp-p5/net/ipv4/sysctl_net_ipv4.c
--- net-2.6-udp-p4/net/ipv4/sysctl_net_ipv4.c   2007-11-15 14:44:21.000000000 
-0500
+++ net-2.6-udp-p5/net/ipv4/sysctl_net_ipv4.c   2007-11-15 14:44:23.000000000 
-0500
@@ -896,6 +896,26 @@ ctl_table ipv4_table[] = {
                .strategy       = &sysctl_intvec,
                .extra1         = &zero
        },
+       {
+               .ctl_name       = CTL_UNNUMBERED,
+               .procname       = "udp_rmem_min",
+               .data           = &sysctl_udp_rmem_min,
+               .maxlen         = sizeof(sysctl_udp_rmem_min),
+               .mode           = 0644,
+               .proc_handler   = &proc_dointvec_minmax,
+               .strategy       = &sysctl_intvec,
+               .extra1         = &zero
+       },
+       {
+               .ctl_name       = CTL_UNNUMBERED,
+               .procname       = "udp_wmem_min",
+               .data           = &sysctl_udp_wmem_min,
+               .maxlen         = sizeof(sysctl_udp_wmem_min),
+               .mode           = 0644,
+               .proc_handler   = &proc_dointvec_minmax,
+               .strategy       = &sysctl_intvec,
+               .extra1         = &zero
+       },
        { .ctl_name = 0 }
 };

diff -pruN net-2.6-udp-p4/net/ipv4/udp.c net-2.6-udp-p5/net/ipv4/udp.c
--- net-2.6-udp-p4/net/ipv4/udp.c       2007-11-15 14:44:21.000000000 -0500
+++ net-2.6-udp-p5/net/ipv4/udp.c       2007-11-15 14:44:23.000000000 -0500
@@ -117,6 +117,8 @@ DEFINE_RWLOCK(udp_hash_lock);

 atomic_t udp_memory_allocated;
 int sysctl_udp_mem __read_mostly;
+int sysctl_udp_rmem_min __read_mostly;
+int sysctl_udp_wmem_min __read_mostly;

 static inline int __udp_lib_lport_inuse(__u16 num,
                                        const struct hlist_head udptable[])
@@ -1027,8 +1029,10 @@ int udp_queue_rcv_skb(struct sock * sk,
        }

        if ((atomic_read(sk->sk_prot->memory_allocated)
-                      + sk_datagram_pages(skb->truesize))
-               > sk->sk_prot->sysctl_mem[0]) {
+            + sk_datagram_pages(skb->truesize))
+           > sk->sk_prot->sysctl_mem[0] &&
+           atomic_read(&sk->sk_rmem_alloc) + skb->truesize
+           > sk->sk_prot->sysctl_rmem[0]) {
                UDP_INC_STATS_BH(UDP_MIB_RCVBUFERRORS, up->pcflag);
                goto drop;
        }
@@ -1471,6 +1475,8 @@ struct proto udp_prot = {
        .get_port          = udp_v4_get_port,
        .memory_allocated  = &udp_memory_allocated,
        .sysctl_mem        = &sysctl_udp_mem,
+       .sysctl_wmem       = &sysctl_udp_wmem_min,
+       .sysctl_rmem       = &sysctl_udp_rmem_min,
        .obj_size          = sizeof(struct udp_sock),
 #ifdef CONFIG_COMPAT
        .compat_setsockopt = compat_udp_setsockopt,
@@ -1678,6 +1684,9 @@ void __init udp_init(void)
        limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
        limit = max(limit, 128UL);
        sysctl_udp_mem = limit / 2 * 3;
+
+       sysctl_udp_rmem_min = SK_DATAGRAM_MEM_QUANTUM;
+       sysctl_udp_wmem_min = SK_DATAGRAM_MEM_QUANTUM;
 }

 EXPORT_SYMBOL(udp_disconnect);
-- 
Hitachi Computer Products (America) Inc.
-
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