netdev - [net-next PATCH v1 15/15] net: sched: drop ingress qdisc lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140726043239.21036.59510.stgit@nitbit.x32>
Date:	Fri, 25 Jul 2014 21:32:41 -0700
From:	John Fastabend <john.fastabend@...il.com>
To:	xiyou.wangcong@...il.com, jhs@...atatu.com, eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
	brouer@...hat.com
Subject: [net-next PATCH v1 15/15] net: sched: drop ingress qdisc lock

After the previous patches to make the filters RCU safe and
support per cpu counters we can drop the qdisc lock around
the ingress qdisc hook.

This is possible because the ingress qdisc is a very basic
qdisc and only updates stats and runs tc_classify. Its the
simplest qdiscs we have.

In order for the per-cpu counters to get invoked the
ingress qdisc must set the LLQDISC flag. We could use per-cpu
counters on all counters but it is only necessary when the
qdisc lock is not held.

Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
---
 net/core/dev.c          |    2 --
 net/sched/sch_ingress.c |    6 ++++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 1f87ad3..beb626b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3506,10 +3506,8 @@ static int ing_filter(struct sk_buff *skb, struct netdev_queue *rxq)
 
 	q = rcu_dereference(rxq->qdisc);
 	if (q != &noop_qdisc) {
-		spin_lock(qdisc_lock(q));
 		if (likely(!test_bit(__QDISC_STATE_DEACTIVATED, &q->state)))
 			result = qdisc_enqueue_root(skb, q);
-		spin_unlock(qdisc_lock(q));
 	}
 
 	return result;
diff --git a/net/sched/sch_ingress.c b/net/sched/sch_ingress.c
index 2423d7b..a81b333 100644
--- a/net/sched/sch_ingress.c
+++ b/net/sched/sch_ingress.c
@@ -88,6 +88,11 @@ static int ingress_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 }
 
 /* ------------------------------------------------------------- */
+static int ingress_init(struct Qdisc *sch, struct nlattr *opt)
+{
+	sch->flags |= TCQ_F_LLQDISC;
+	return 0;
+}
 
 static void ingress_destroy(struct Qdisc *sch)
 {
@@ -122,6 +127,7 @@ static const struct Qdisc_class_ops ingress_class_ops = {
 };
 
 static struct Qdisc_ops ingress_qdisc_ops __read_mostly = {
+	.init		=	ingress_init,
 	.cl_ops		=	&ingress_class_ops,
 	.id		=	"ingress",
 	.priv_size	=	sizeof(struct ingress_qdisc_data),

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html