Commit 8f4f9c93 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'net-dev-tracking-improvements' 



Eric Dumazet says:

====================
net: device tracking improvements

Main goal of this series is to be able to detect the following case
which apparently is still haunting us.

dev_hold_track(dev, tracker_1, GFP_ATOMIC);
    dev_hold(dev);
    dev_put(dev);
    dev_put(dev);              // Should complain loudly here.
dev_put_track(dev, tracker_1); // instead of here (as before this series)

v2: third patch:
  I replaced the dev_put() in linkwatch_do_dev() with __dev_put().
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents cc306350 4c6c11ea

include/linux/netdevice.h

+46 −23
Original line number Diff line number Diff line
@@ -3817,14 +3817,7 @@ extern unsigned int netdev_budget_usecs; 
/* Called by rtnetlink.c:rtnl_unlock() */

void netdev_run_todo(void);



/**

 *	dev_put - release reference to device

 *	@dev: network device

 *

 * Release reference to device to allow it to be freed.

 * Try using dev_put_track() instead.

 */

static inline void dev_put(struct net_device *dev)

static inline void __dev_put(struct net_device *dev)

{

	if (dev) {

#ifdef CONFIG_PCPU_DEV_REFCNT
@@ -3835,14 +3828,7 @@ static inline void dev_put(struct net_device *dev) 
	}

}



/**

 *	dev_hold - get reference to device

 *	@dev: network device

 *

 * Hold reference to device to keep it from being freed.

 * Try using dev_hold_track() instead.

 */

static inline void dev_hold(struct net_device *dev)

static inline void __dev_hold(struct net_device *dev)

{

	if (dev) {

#ifdef CONFIG_PCPU_DEV_REFCNT
@@ -3853,11 +3839,24 @@ static inline void dev_hold(struct net_device *dev) 
	}

}



static inline void __netdev_tracker_alloc(struct net_device *dev,

					  netdevice_tracker *tracker,

					  gfp_t gfp)

{

#ifdef CONFIG_NET_DEV_REFCNT_TRACKER

	ref_tracker_alloc(&dev->refcnt_tracker, tracker, gfp);

#endif

}



/* netdev_tracker_alloc() can upgrade a prior untracked reference

 * taken by dev_get_by_name()/dev_get_by_index() to a tracked one.

 */

static inline void netdev_tracker_alloc(struct net_device *dev,

					netdevice_tracker *tracker, gfp_t gfp)

{

#ifdef CONFIG_NET_DEV_REFCNT_TRACKER

	ref_tracker_alloc(&dev->refcnt_tracker, tracker, gfp);

	refcount_dec(&dev->refcnt_tracker.no_tracker);

	__netdev_tracker_alloc(dev, tracker, gfp);

#endif

}
@@ -3873,8 +3872,8 @@ static inline void dev_hold_track(struct net_device *dev, 
				  netdevice_tracker *tracker, gfp_t gfp)

{

	if (dev) {

		dev_hold(dev);

		netdev_tracker_alloc(dev, tracker, gfp);

		__dev_hold(dev);

		__netdev_tracker_alloc(dev, tracker, gfp);

	}

}
@@ -3883,8 +3882,32 @@ static inline void dev_put_track(struct net_device *dev, 
{

	if (dev) {

		netdev_tracker_free(dev, tracker);

		dev_put(dev);

		__dev_put(dev);

	}

}



/**

 *	dev_hold - get reference to device

 *	@dev: network device

 *

 * Hold reference to device to keep it from being freed.

 * Try using dev_hold_track() instead.

 */

static inline void dev_hold(struct net_device *dev)

{

	dev_hold_track(dev, NULL, GFP_ATOMIC);

}



/**

 *	dev_put - release reference to device

 *	@dev: network device

 *

 * Release reference to device to allow it to be freed.

 * Try using dev_put_track() instead.

 */

static inline void dev_put(struct net_device *dev)

{

	dev_put_track(dev, NULL);

}



static inline void dev_replace_track(struct net_device *odev,
@@ -3895,11 +3918,11 @@ static inline void dev_replace_track(struct net_device *odev, 
	if (odev)

		netdev_tracker_free(odev, tracker);



	dev_hold(ndev);

	dev_put(odev);

	__dev_hold(ndev);

	__dev_put(odev);



	if (ndev)

		netdev_tracker_alloc(ndev, tracker, gfp);

		__netdev_tracker_alloc(ndev, tracker, gfp);

}



/* Carrier loss detection, dial on demand. The functions netif_carrier_on

include/linux/ref_tracker.h

+4 −0
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ struct ref_tracker_dir { 
	spinlock_t		lock;

	unsigned int		quarantine_avail;

	refcount_t		untracked;

	refcount_t		no_tracker;

	bool			dead;

	struct list_head	list; /* List of active trackers */

	struct list_head	quarantine; /* List of dead trackers */

#endif
@@ -26,7 +28,9 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir, 
	INIT_LIST_HEAD(&dir->quarantine);

	spin_lock_init(&dir->lock);

	dir->quarantine_avail = quarantine_count;

	dir->dead = false;

	refcount_set(&dir->untracked, 1);

	refcount_set(&dir->no_tracker, 1);

	stack_depot_init();

}

lib/ref_tracker.c

+16 −1
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir) 
	unsigned long flags;

	bool leak = false;



	dir->dead = true;

	spin_lock_irqsave(&dir->lock, flags);

	list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {

		list_del(&tracker->head);
@@ -37,6 +38,7 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir) 
	spin_unlock_irqrestore(&dir->lock, flags);

	WARN_ON_ONCE(leak);

	WARN_ON_ONCE(refcount_read(&dir->untracked) != 1);

	WARN_ON_ONCE(refcount_read(&dir->no_tracker) != 1);

}

EXPORT_SYMBOL(ref_tracker_dir_exit);
@@ -72,6 +74,12 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir, 
	gfp_t gfp_mask = gfp;

	unsigned long flags;



	WARN_ON_ONCE(dir->dead);



	if (!trackerp) {

		refcount_inc(&dir->no_tracker);

		return 0;

	}

	if (gfp & __GFP_DIRECT_RECLAIM)

		gfp_mask |= __GFP_NOFAIL;

	*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
@@ -95,11 +103,18 @@ int ref_tracker_free(struct ref_tracker_dir *dir, 
		     struct ref_tracker **trackerp)

{

	unsigned long entries[REF_TRACKER_STACK_ENTRIES];

	struct ref_tracker *tracker = *trackerp;

	depot_stack_handle_t stack_handle;

	struct ref_tracker *tracker;

	unsigned int nr_entries;

	unsigned long flags;



	WARN_ON_ONCE(dir->dead);



	if (!trackerp) {

		refcount_dec(&dir->no_tracker);

		return 0;

	}

	tracker = *trackerp;

	if (!tracker) {

		refcount_dec(&dir->untracked);

		return -EEXIST;

net/core/dev.c

+1 −1
Original line number Diff line number Diff line
@@ -10172,7 +10172,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name, 
	dev->pcpu_refcnt = alloc_percpu(int);

	if (!dev->pcpu_refcnt)

		goto free_dev;

	dev_hold(dev);

	__dev_hold(dev);

#else

	refcount_set(&dev->dev_refcnt, 1);

#endif

net/core/link_watch.c

+3 −3
Original line number Diff line number Diff line
@@ -166,10 +166,10 @@ static void linkwatch_do_dev(struct net_device *dev) 


		netdev_state_change(dev);

	}

	/* Note: our callers are responsible for

	 * calling netdev_tracker_free().

	/* Note: our callers are responsible for calling netdev_tracker_free().

	 * This is the reason we use __dev_put() instead of dev_put().

	 */

	dev_put(dev);

	__dev_put(dev);

}



static void __linkwatch_run_queue(int urgent_only)