From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 29 Jan 2010 04:05:52 +0000 (+0000)
Subject: xfrm: avoid spinlock in get_acqseq()
X-Git-Tag: v2.6.34-rc1~233^2~472
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=28aecb9d7728dc26bf03ce7925fe622023a83a2a;p=linux.git

xfrm: avoid spinlock in get_acqseq()

Use atomic_inc_return() in get_acqseq() to avoid taking a spinlock

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

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 4744b1f6372f..e2aacf0ba013 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -3019,12 +3019,11 @@ static int pfkey_send_policy_notify(struct xfrm_policy *xp, int dir, struct km_e
 static u32 get_acqseq(void)
 {
 	u32 res;
-	static u32 acqseq;
-	static DEFINE_SPINLOCK(acqseq_lock);
+	static atomic_t acqseq;
 
-	spin_lock_bh(&acqseq_lock);
-	res = (++acqseq ? : ++acqseq);
-	spin_unlock_bh(&acqseq_lock);
+	do {
+		res = atomic_inc_return(&acqseq);
+	} while (!res);
 	return res;
 }