Commit 1b23cdbd authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

net: protect netdev->napi_list with netdev_lock() 



Hold netdev->lock when NAPIs are getting added or removed.
This will allow safe access to NAPI instances of a net_device
without rtnl_lock.

Create a family of helpers which assume the lock is already taken.
Switch iavf to them, as it makes extensive use of netdev->lock,
already.

Reviewed-by: default avatarJoe Damato <jdamato@fastly.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250115035319.559603-6-kuba@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 5112457f

drivers/net/ethernet/intel/iavf/iavf_main.c

+3 −3
Original line number Diff line number Diff line
@@ -1800,7 +1800,7 @@ static int iavf_alloc_q_vectors(struct iavf_adapter *adapter) 
		q_vector->v_idx = q_idx;

		q_vector->reg_idx = q_idx;

		cpumask_copy(&q_vector->affinity_mask, cpu_possible_mask);

		netif_napi_add(adapter->netdev, &q_vector->napi,

		netif_napi_add_locked(adapter->netdev, &q_vector->napi,

				      iavf_napi_poll);

	}
@@ -1827,7 +1827,7 @@ static void iavf_free_q_vectors(struct iavf_adapter *adapter) 
	for (q_idx = 0; q_idx < num_q_vectors; q_idx++) {

		struct iavf_q_vector *q_vector = &adapter->q_vectors[q_idx];



		netif_napi_del(&q_vector->napi);

		netif_napi_del_locked(&q_vector->napi);

	}

	kfree(adapter->q_vectors);

	adapter->q_vectors = NULL;

include/linux/netdevice.h

+47 −7
Original line number Diff line number Diff line
@@ -2456,7 +2456,7 @@ struct net_device { 
	 * Drivers are free to use it for other protection.

	 *

	 * Protects:

	 *	@net_shaper_hierarchy, @reg_state

	 *	@napi_list, @net_shaper_hierarchy, @reg_state

	 *

	 * Partially protects (writers must hold both @lock and rtnl_lock):

	 *	@up
@@ -2712,8 +2712,19 @@ static inline void netif_napi_set_irq(struct napi_struct *napi, int irq) 
 */

#define NAPI_POLL_WEIGHT 64



void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,

			   int (*poll)(struct napi_struct *, int), int weight);

void netif_napi_add_weight_locked(struct net_device *dev,

				  struct napi_struct *napi,

				  int (*poll)(struct napi_struct *, int),

				  int weight);



static inline void

netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,

		      int (*poll)(struct napi_struct *, int), int weight)

{

	netdev_lock(dev);

	netif_napi_add_weight_locked(dev, napi, poll, weight);

	netdev_unlock(dev);

}



/**

 * netif_napi_add() - initialize a NAPI context
@@ -2731,6 +2742,13 @@ netif_napi_add(struct net_device *dev, struct napi_struct *napi, 
	netif_napi_add_weight(dev, napi, poll, NAPI_POLL_WEIGHT);

}



static inline void

netif_napi_add_locked(struct net_device *dev, struct napi_struct *napi,

		      int (*poll)(struct napi_struct *, int))

{

	netif_napi_add_weight_locked(dev, napi, poll, NAPI_POLL_WEIGHT);

}



static inline void

netif_napi_add_tx_weight(struct net_device *dev,

			 struct napi_struct *napi,
@@ -2741,6 +2759,15 @@ netif_napi_add_tx_weight(struct net_device *dev, 
	netif_napi_add_weight(dev, napi, poll, weight);

}



static inline void

netif_napi_add_config_locked(struct net_device *dev, struct napi_struct *napi,

			     int (*poll)(struct napi_struct *, int), int index)

{

	napi->index = index;

	napi->config = &dev->napi_config[index];

	netif_napi_add_weight_locked(dev, napi, poll, NAPI_POLL_WEIGHT);

}



/**

 * netif_napi_add_config - initialize a NAPI context with persistent config

 * @dev: network device
@@ -2752,9 +2779,9 @@ static inline void 
netif_napi_add_config(struct net_device *dev, struct napi_struct *napi,

		      int (*poll)(struct napi_struct *, int), int index)

{

	napi->index = index;

	napi->config = &dev->napi_config[index];

	netif_napi_add_weight(dev, napi, poll, NAPI_POLL_WEIGHT);

	netdev_lock(dev);

	netif_napi_add_config_locked(dev, napi, poll, index);

	netdev_unlock(dev);

}



/**
@@ -2774,6 +2801,8 @@ static inline void netif_napi_add_tx(struct net_device *dev, 
	netif_napi_add_tx_weight(dev, napi, poll, NAPI_POLL_WEIGHT);

}



void __netif_napi_del_locked(struct napi_struct *napi);



/**

 *  __netif_napi_del - remove a NAPI context

 *  @napi: NAPI context
@@ -2782,7 +2811,18 @@ static inline void netif_napi_add_tx(struct net_device *dev, 
 * containing @napi. Drivers might want to call this helper to combine

 * all the needed RCU grace periods into a single one.

 */

void __netif_napi_del(struct napi_struct *napi);

static inline void __netif_napi_del(struct napi_struct *napi)

{

	netdev_lock(napi->dev);

	__netif_napi_del_locked(napi);

	netdev_unlock(napi->dev);

}



static inline void netif_napi_del_locked(struct napi_struct *napi)

{

	__netif_napi_del_locked(napi);

	synchronize_net();

}



/**

 *  netif_napi_del - remove a NAPI context

net/core/dev.c

+10 −5
Original line number Diff line number Diff line
@@ -6910,9 +6910,12 @@ netif_napi_dev_list_add(struct net_device *dev, struct napi_struct *napi) 
	list_add_rcu(&napi->dev_list, higher); /* adds after higher */

}



void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,

			   int (*poll)(struct napi_struct *, int), int weight)

void netif_napi_add_weight_locked(struct net_device *dev,

				  struct napi_struct *napi,

				  int (*poll)(struct napi_struct *, int),

				  int weight)

{

	netdev_assert_locked(dev);

	if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))

		return;
@@ -6953,7 +6956,7 @@ void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi, 
		dev->threaded = false;

	netif_napi_set_irq(napi, -1);

}

EXPORT_SYMBOL(netif_napi_add_weight);

EXPORT_SYMBOL(netif_napi_add_weight_locked);



void napi_disable(struct napi_struct *n)

{
@@ -7024,8 +7027,10 @@ static void flush_gro_hash(struct napi_struct *napi) 
}



/* Must be called in process context */

void __netif_napi_del(struct napi_struct *napi)

void __netif_napi_del_locked(struct napi_struct *napi)

{

	netdev_assert_locked(napi->dev);



	if (!test_and_clear_bit(NAPI_STATE_LISTED, &napi->state))

		return;
@@ -7045,7 +7050,7 @@ void __netif_napi_del(struct napi_struct *napi) 
		napi->thread = NULL;

	}

}

EXPORT_SYMBOL(__netif_napi_del);

EXPORT_SYMBOL(__netif_napi_del_locked);



static int __napi_poll(struct napi_struct *n, bool *repoll)

{