From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 28 Apr 2010 21:35:48 +0000 (-0700)
Subject: net: speedup udp receive path
X-Git-Tag: v2.6.35-rc1~473^2~304
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4b0b72f7dd617b13abd1b04c947e15873e011a24;p=pandora-kernel.git

net: speedup udp receive path

Since commit 95766fff ([UDP]: Add memory accounting.),
each received packet needs one extra sock_lock()/sock_release() pair.

This added latency because of possible backlog handling. Then later,
ticket spinlocks added yet another latency source in case of DDOS.

This patch introduces lock_sock_bh() and unlock_sock_bh()
synchronization primitives, avoiding one atomic operation and backlog
processing.

skb_free_datagram_locked() uses them instead of full blown
lock_sock()/release_sock(). skb is orphaned inside locked section for
proper socket memory reclaim, and finally freed outside of it.

UDP receive path now take the socket spinlock only once.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

Reading git-diff-tree failed