tcp: restore correct limit

Commit c43b874d (tcp: properly initialize tcp memory limits) tried
to fix a regression added in commits 4acb4190 & 3dc43e3e,
but still get it wrong.

Result is machines with low amount of memory have too small tcp_rmem[2]
value and slow tcp receives : Per socket limit being 1/1024 of memory
instead of 1/128 in old kernels, so rcv window is capped to small
values.

Fix this to match comment and previous behavior.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Glauber Costa <glommer@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -3302,8 +3302,7 @@ void __init tcp_init(void)
 
 	tcp_init_mem(&init_net);
 	/* Set per-socket limits to no more than 1/128 the pressure threshold */
-	limit = nr_free_buffer_pages() << (PAGE_SHIFT - 10);
-	limit = max(limit, 128UL);
+	limit = nr_free_buffer_pages() << (PAGE_SHIFT - 7);
 	max_share = min(4UL*1024*1024, limit);
 
 	sysctl_tcp_wmem[0] = SK_MEM_QUANTUM;