Commit 004d1383 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net-sysfs: convert dev->operstate reads to lockless ones 



operstate_show() can omit dev_base_lock acquisition only
to read dev->operstate.

Annotate accesses to dev->operstate.

Writers still acquire dev_base_lock for mutual exclusion.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c7d52737

net/bridge/br_netlink.c

+2 −1
Original line number Diff line number Diff line
@@ -455,7 +455,8 @@ static int br_fill_ifinfo(struct sk_buff *skb, 
			  u32 filter_mask, const struct net_device *dev,

			  bool getlink)

{

	u8 operstate = netif_running(dev) ? dev->operstate : IF_OPER_DOWN;

	u8 operstate = netif_running(dev) ? READ_ONCE(dev->operstate) :

					    IF_OPER_DOWN;

	struct nlattr *af = NULL;

	struct net_bridge *br;

	struct ifinfomsg *hdr;

net/core/link_watch.c

+2 −2
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ static void rfc2863_policy(struct net_device *dev) 
{

	unsigned char operstate = default_operstate(dev);



	if (operstate == dev->operstate)

	if (operstate == READ_ONCE(dev->operstate))

		return;



	write_lock(&dev_base_lock);
@@ -87,7 +87,7 @@ static void rfc2863_policy(struct net_device *dev) 
		break;

	}



	dev->operstate = operstate;

	WRITE_ONCE(dev->operstate, operstate);



	write_unlock(&dev_base_lock);

}

net/core/net-sysfs.c

+1 −3
Original line number Diff line number Diff line
@@ -325,11 +325,9 @@ static ssize_t operstate_show(struct device *dev, 
	const struct net_device *netdev = to_net_dev(dev);

	unsigned char operstate;



	read_lock(&dev_base_lock);

	operstate = netdev->operstate;

	operstate = READ_ONCE(netdev->operstate);

	if (!netif_running(netdev))

		operstate = IF_OPER_DOWN;

	read_unlock(&dev_base_lock);



	if (operstate >= ARRAY_SIZE(operstates))

		return -EINVAL; /* should not happen */

net/core/rtnetlink.c

+2 −2
Original line number Diff line number Diff line
@@ -866,9 +866,9 @@ static void set_operstate(struct net_device *dev, unsigned char transition) 
		break;

	}



	if (dev->operstate != operstate) {

	if (READ_ONCE(dev->operstate) != operstate) {

		write_lock(&dev_base_lock);

		dev->operstate = operstate;

		WRITE_ONCE(dev->operstate, operstate);

		write_unlock(&dev_base_lock);

		netdev_state_change(dev);

	}

net/hsr/hsr_device.c

+5 −5
Original line number Diff line number Diff line
@@ -31,8 +31,8 @@ static bool is_slave_up(struct net_device *dev) 
static void __hsr_set_operstate(struct net_device *dev, int transition)

{

	write_lock(&dev_base_lock);

	if (dev->operstate != transition) {

		dev->operstate = transition;

	if (READ_ONCE(dev->operstate) != transition) {

		WRITE_ONCE(dev->operstate, transition);

		write_unlock(&dev_base_lock);

		netdev_state_change(dev);

	} else {
@@ -78,14 +78,14 @@ static void hsr_check_announce(struct net_device *hsr_dev, 


	hsr = netdev_priv(hsr_dev);



	if (hsr_dev->operstate == IF_OPER_UP && old_operstate != IF_OPER_UP) {

	if (READ_ONCE(hsr_dev->operstate) == IF_OPER_UP && old_operstate != IF_OPER_UP) {

		/* Went up */

		hsr->announce_count = 0;

		mod_timer(&hsr->announce_timer,

			  jiffies + msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL));

	}



	if (hsr_dev->operstate != IF_OPER_UP && old_operstate == IF_OPER_UP)

	if (READ_ONCE(hsr_dev->operstate) != IF_OPER_UP && old_operstate == IF_OPER_UP)

		/* Went down */

		del_timer(&hsr->announce_timer);

}
@@ -100,7 +100,7 @@ void hsr_check_carrier_and_operstate(struct hsr_priv *hsr) 
	/* netif_stacked_transfer_operstate() cannot be used here since

	 * it doesn't set IF_OPER_LOWERLAYERDOWN (?)

	 */

	old_operstate = master->dev->operstate;

	old_operstate = READ_ONCE(master->dev->operstate);

	has_carrier = hsr_check_carrier(master);

	hsr_set_operstate(master, has_carrier);

	hsr_check_announce(master->dev, old_operstate);