[PATCH net-next] net/sched: taprio: remove unnecessary taprio_list_lock

From: Vladimir Oltean
Date: Wed Sep 21 2022 - 05:57:07 EST


The 3 functions that want access to the taprio_list:
taprio_dev_notifier(), taprio_destroy() and taprio_init() are all called
with the rtnl_mutex held, therefore implicitly serialized with respect
to each other. A spin lock serves no purpose.

Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
---
net/sched/sch_taprio.c | 7 -------
1 file changed, 7 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 1ab92968c1e3..163255e0cd77 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -27,7 +27,6 @@
#include <net/tcp.h>

static LIST_HEAD(taprio_list);
-static DEFINE_SPINLOCK(taprio_list_lock);

#define TAPRIO_ALL_GATES_OPEN -1

@@ -1082,7 +1081,6 @@ static int taprio_dev_notifier(struct notifier_block *nb, unsigned long event,
if (event != NETDEV_UP && event != NETDEV_CHANGE)
return NOTIFY_DONE;

- spin_lock(&taprio_list_lock);
list_for_each_entry(q, &taprio_list, taprio_list) {
qdev = qdisc_dev(q->root);
if (qdev == dev) {
@@ -1090,7 +1088,6 @@ static int taprio_dev_notifier(struct notifier_block *nb, unsigned long event,
break;
}
}
- spin_unlock(&taprio_list_lock);

if (found)
taprio_set_picos_per_byte(dev, q);
@@ -1602,9 +1599,7 @@ static void taprio_destroy(struct Qdisc *sch)
struct sched_gate_list *oper, *admin;
unsigned int i;

- spin_lock(&taprio_list_lock);
list_del(&q->taprio_list);
- spin_unlock(&taprio_list_lock);

/* Note that taprio_reset() might not be called if an error
* happens in qdisc_create(), after taprio_init() has been called.
@@ -1653,9 +1648,7 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
q->clockid = -1;
q->flags = TAPRIO_FLAGS_INVALID;

- spin_lock(&taprio_list_lock);
list_add(&q->taprio_list, &taprio_list);
- spin_unlock(&taprio_list_lock);

if (sch->parent != TC_H_ROOT) {
NL_SET_ERR_MSG_MOD(extack, "Can only be attached as root qdisc");
--
2.34.1