netdev - [PATCH net-next v3 08/10] net: sched: protect block idr with spinlock

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Date:   Mon, 24 Sep 2018 19:22:56 +0300
From:   Vlad Buslov <vladbu@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net, stephen@...workplumber.org,
        ktkhai@...tuozzo.com, nicolas.dichtel@...nd.com,
        gregkh@...uxfoundation.org, mark.rutland@....com, leon@...nel.org,
        paulmck@...ux.vnet.ibm.com, fw@...len.de, dsahern@...il.com,
        christian@...uner.io, lucien.xin@...il.com,
        jakub.kicinski@...ronome.com, jbenc@...hat.com,
        Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net-next v3 08/10] net: sched: protect block idr with spinlock

Protect block idr access with spinlock, instead of relying on rtnl lock.
Take tn->idr_lock spinlock during block insertion and removal.

Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
Acked-by: Jiri Pirko <jiri@...lanox.com>
---
 net/sched/cls_api.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index cb7422af5e51..5a21888d0ee9 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -473,6 +473,7 @@ tcf_chain0_head_change_cb_del(struct tcf_block *block,
 }
 
 struct tcf_net {
+	spinlock_t idr_lock; /* Protects idr */
 	struct idr idr;
 };
 
@@ -482,16 +483,25 @@ static int tcf_block_insert(struct tcf_block *block, struct net *net,
 			    struct netlink_ext_ack *extack)
 {
 	struct tcf_net *tn = net_generic(net, tcf_net_id);
+	int err;
+
+	idr_preload(GFP_KERNEL);
+	spin_lock(&tn->idr_lock);
+	err = idr_alloc_u32(&tn->idr, block, &block->index, block->index,
+			    GFP_NOWAIT);
+	spin_unlock(&tn->idr_lock);
+	idr_preload_end();
 
-	return idr_alloc_u32(&tn->idr, block, &block->index, block->index,
-			     GFP_KERNEL);
+	return err;
 }
 
 static void tcf_block_remove(struct tcf_block *block, struct net *net)
 {
 	struct tcf_net *tn = net_generic(net, tcf_net_id);
 
+	spin_lock(&tn->idr_lock);
 	idr_remove(&tn->idr, block->index);
+	spin_unlock(&tn->idr_lock);
 }
 
 static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
@@ -2278,6 +2288,7 @@ static __net_init int tcf_net_init(struct net *net)
 {
 	struct tcf_net *tn = net_generic(net, tcf_net_id);
 
+	spin_lock_init(&tn->idr_lock);
 	idr_init(&tn->idr);
 	return 0;
 }
-- 
2.7.5