[PATCH net-next v2] net: sched: don't disable bh when accessing action idr

From: Vlad Buslov <hidden>
Date: 2018-05-21 20:03:22
Also in: lkml
Subsystem: networking [general], tc subsystem, the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds

Initial net_device implementation used ingress_lock spinlock to synchronize
ingress path of device. This lock was used in both process and bh context.
In some code paths action map lock was obtained while holding ingress_lock.
Commit e1e992e52faa ("[NET_SCHED] protect action config/dump from irqs")
modified actions to always disable bh, while using action map lock, in
order to prevent deadlock on ingress_lock in softirq. This lock was removed
from net_device, so disabling bh, while accessing action map, is no longer
necessary.

Replace all action idr spinlock usage with regular calls that do not
disable bh.

Signed-off-by: Vlad Buslov <redacted>
---
 net/sched/act_api.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 72251241665a..3f4cf930f809 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c

@@ -77,9 +77,9 @@ static void free_tcf(struct tc_action *p)
 
 static void tcf_idr_remove(struct tcf_idrinfo *idrinfo, struct tc_action *p)
 {
-	spin_lock_bh(&idrinfo->lock);
+	spin_lock(&idrinfo->lock);
 	idr_remove(&idrinfo->action_idr, p->tcfa_index);
-	spin_unlock_bh(&idrinfo->lock);
+	spin_unlock(&idrinfo->lock);
 	gen_kill_estimator(&p->tcfa_rate_est);
 	free_tcf(p);
 }

@@ -156,7 +156,7 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 	struct tc_action *p;
 	unsigned long id = 1;
 
-	spin_lock_bh(&idrinfo->lock);
+	spin_lock(&idrinfo->lock);
 
 	s_i = cb->args[0];

@@ -191,7 +191,7 @@ static int tcf_dump_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
 	if (index >= 0)
 		cb->args[0] = index + 1;
 
-	spin_unlock_bh(&idrinfo->lock);
+	spin_unlock(&idrinfo->lock);
 	if (n_i) {
 		if (act_flags & TCA_FLAG_LARGE_DUMP_ON)
 			cb->args[1] = n_i;

@@ -261,9 +261,9 @@ static struct tc_action *tcf_idr_lookup(u32 index, struct tcf_idrinfo *idrinfo)
 {
 	struct tc_action *p = NULL;
 
-	spin_lock_bh(&idrinfo->lock);
+	spin_lock(&idrinfo->lock);
 	p = idr_find(&idrinfo->action_idr, index);
-	spin_unlock_bh(&idrinfo->lock);
+	spin_unlock(&idrinfo->lock);
 
 	return p;
 }

@@ -323,7 +323,7 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
 	}
 	spin_lock_init(&p->tcfa_lock);
 	idr_preload(GFP_KERNEL);
-	spin_lock_bh(&idrinfo->lock);
+	spin_lock(&idrinfo->lock);
 	/* user doesn't specify an index */
 	if (!index) {
 		index = 1;

@@ -331,7 +331,7 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
 	} else {
 		err = idr_alloc_u32(idr, NULL, &index, index, GFP_ATOMIC);
 	}
-	spin_unlock_bh(&idrinfo->lock);
+	spin_unlock(&idrinfo->lock);
 	idr_preload_end();
 	if (err)
 		goto err3;

@@ -369,9 +369,9 @@ void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a)
 {
 	struct tcf_idrinfo *idrinfo = tn->idrinfo;
 
-	spin_lock_bh(&idrinfo->lock);
+	spin_lock(&idrinfo->lock);
 	idr_replace(&idrinfo->action_idr, a, a->tcfa_index);
-	spin_unlock_bh(&idrinfo->lock);
+	spin_unlock(&idrinfo->lock);
 }
 EXPORT_SYMBOL(tcf_idr_insert);

-- 
2.7.5

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