[PATCH] TCP acts like it is always out of memory.

[Stephen Hemminger <shemminger@xxxxxxxx>]

Current 2.6.7 tree acts as if it is alway under memory pressure because
a recent change did a s/tcp_memory_pressure/tcp_prot.memory_pressure/.
The problem is tcp_prot.memory_pressure is a pointer, so it is always non-zero!

Rather than using *tcp_prot.memory_pressure, just go back to looking at
tcp_memory_pressure.

Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxx>

diff -Nru a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
--- a/net/ipv4/tcp_input.c      2004-07-01 13:36:58 -07:00
+++ b/net/ipv4/tcp_input.c      2004-07-01 13:36:58 -07:00
@@ -259,7 +259,7 @@
        /* Check #1 */
        if (tp->rcv_ssthresh < tp->window_clamp &&
            (int)tp->rcv_ssthresh < tcp_space(sk) &&
-           !tcp_prot.memory_pressure) {
+           !tcp_memory_pressure) {
                int incr;
 
                /* Check #2. Increase window, if skb with such overhead
@@ -349,7 +349,7 @@
        if (ofo_win) {
                if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] &&
                    !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
-                   !tcp_prot.memory_pressure &&
+                   !tcp_memory_pressure &&
                    atomic_read(&tcp_memory_allocated) < sysctl_tcp_mem[0])
                        sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),
                                            sysctl_tcp_rmem[2]);
@@ -3764,7 +3764,7 @@
 
        if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
                tcp_clamp_window(sk, tp);
-       else if (tcp_prot.memory_pressure)
+       else if (tcp_memory_pressure)
                tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
 
        tcp_collapse_ofo_queue(sk);
@@ -3844,7 +3844,7 @@
 
        if (tp->packets_out < tp->snd_cwnd &&
            !(sk->sk_userlocks & SOCK_SNDBUF_LOCK) &&
-           !tcp_prot.memory_pressure &&
+           !tcp_memory_pressure &&
            atomic_read(&tcp_memory_allocated) < sysctl_tcp_mem[0]) {
                int sndmem = max_t(u32, tp->mss_clamp, tp->mss_cache) +
                        MAX_TCP_HEADER + 16 + sizeof(struct sk_buff),
diff -Nru a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
--- a/net/ipv4/tcp_output.c     2004-07-01 13:36:58 -07:00
+++ b/net/ipv4/tcp_output.c     2004-07-01 13:36:58 -07:00
@@ -672,7 +672,7 @@
        if (free_space < full_space/2) {
                tp->ack.quick = 0;
 
-               if (tcp_prot.memory_pressure)
+               if (tcp_memory_pressure)
                        tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U*tp->advmss);
 
                if (free_space < mss)
diff -Nru a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
--- a/net/ipv4/tcp_timer.c      2004-07-01 13:36:58 -07:00
+++ b/net/ipv4/tcp_timer.c      2004-07-01 13:36:58 -07:00
@@ -257,7 +257,7 @@
        TCP_CHECK_TIMER(sk);
 
 out:
-       if (tcp_prot.memory_pressure)
+       if (tcp_memory_pressure)
                sk_stream_mem_reclaim(sk);
 out_unlock:
        bh_unlock_sock(sk);