Commit 4d42b37d authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: convert dev->reg_state to u8 



Prepares things so that dev->reg_state reads can be lockless,
by adding WRITE_ONCE() on write side.

READ_ONCE()/WRITE_ONCE() do not support bitfields.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a6473fe9

include/linux/netdevice.h

+14 −9
Original line number Diff line number Diff line
@@ -1815,6 +1815,15 @@ enum netdev_stat_type { 
	NETDEV_PCPU_STAT_DSTATS, /* struct pcpu_dstats */

};



enum netdev_reg_state {

	NETREG_UNINITIALIZED = 0,

	NETREG_REGISTERED,	/* completed register_netdevice */

	NETREG_UNREGISTERING,	/* called unregister_netdevice */

	NETREG_UNREGISTERED,	/* completed unregister todo */

	NETREG_RELEASED,	/* called free_netdev */

	NETREG_DUMMY,		/* dummy device for NAPI poll */

};



/**

 *	struct net_device - The DEVICE structure.

 *
@@ -2372,13 +2381,7 @@ struct net_device { 


	struct list_head	link_watch_list;



	enum { NETREG_UNINITIALIZED=0,

	       NETREG_REGISTERED,	/* completed register_netdevice */

	       NETREG_UNREGISTERING,	/* called unregister_netdevice */

	       NETREG_UNREGISTERED,	/* completed unregister todo */

	       NETREG_RELEASED,		/* called free_netdev */

	       NETREG_DUMMY,		/* dummy device for NAPI poll */

	} reg_state:8;

	u8 reg_state;



	bool dismantle;
@@ -5254,7 +5257,9 @@ static inline const char *netdev_name(const struct net_device *dev) 


static inline const char *netdev_reg_state(const struct net_device *dev)

{

	switch (dev->reg_state) {

	u8 reg_state = READ_ONCE(dev->reg_state);



	switch (reg_state) {

	case NETREG_UNINITIALIZED: return " (uninitialized)";

	case NETREG_REGISTERED: return "";

	case NETREG_UNREGISTERING: return " (unregistering)";
@@ -5263,7 +5268,7 @@ static inline const char *netdev_reg_state(const struct net_device *dev) 
	case NETREG_DUMMY: return " (dummy)";

	}



	WARN_ONCE(1, "%s: unknown reg_state %d\n", dev->name, dev->reg_state);

	WARN_ONCE(1, "%s: unknown reg_state %d\n", dev->name, reg_state);

	return " (unknown)";

}

net/core/dev.c

+4 −4
Original line number Diff line number Diff line
@@ -10339,7 +10339,7 @@ int register_netdevice(struct net_device *dev) 


	ret = netdev_register_kobject(dev);

	write_lock(&dev_base_lock);

	dev->reg_state = ret ? NETREG_UNREGISTERED : NETREG_REGISTERED;

	WRITE_ONCE(dev->reg_state, ret ? NETREG_UNREGISTERED : NETREG_REGISTERED);

	write_unlock(&dev_base_lock);

	if (ret)

		goto err_uninit_notify;
@@ -10630,7 +10630,7 @@ void netdev_run_todo(void) 
		}



		write_lock(&dev_base_lock);

		dev->reg_state = NETREG_UNREGISTERED;

		WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERED);

		write_unlock(&dev_base_lock);

		linkwatch_sync_dev(dev);

	}
@@ -11050,7 +11050,7 @@ void free_netdev(struct net_device *dev) 
	}



	BUG_ON(dev->reg_state != NETREG_UNREGISTERED);

	dev->reg_state = NETREG_RELEASED;

	WRITE_ONCE(dev->reg_state, NETREG_RELEASED);



	/* will free via device release */

	put_device(&dev->dev);
@@ -11140,7 +11140,7 @@ void unregister_netdevice_many_notify(struct list_head *head, 
		/* And unlink it from device chain. */

		write_lock(&dev_base_lock);

		unlist_netdevice(dev, false);

		dev->reg_state = NETREG_UNREGISTERING;

		WRITE_ONCE(dev->reg_state, NETREG_UNREGISTERING);

		write_unlock(&dev_base_lock);

	}

	flush_all_backlogs();