Commit 58caed3d authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

netdev: reshuffle netif_napi_add() APIs to allow dropping weight 



Most drivers should not have to worry about selecting the right
weight for their NAPI instances and pass NAPI_POLL_WEIGHT.
It'd be best if we didn't require the argument at all and selected
the default internally.

This change prepares the ground for such reshuffling, allowing
for a smooth transition. The following API should remain after
the next release cycle:
  netif_napi_add()
  netif_napi_add_weight()
  netif_napi_add_tx()
  netif_napi_add_tx_weight()
Where the _weight() variants take an explicit weight argument.
I opted for a _weight() suffix rather than a __ prefix, because
we use __ in places to mean that caller needs to also issue a
synchronize_net() call.

Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20220502232703.396351-1-kuba@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 7d4e91e0

include/linux/netdevice.h

+33 −17
Original line number Diff line number Diff line
@@ -2499,8 +2499,11 @@ static inline void *netdev_priv(const struct net_device *dev) 
 */

#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);



/**

 *	netif_napi_add - initialize a NAPI context

 * netif_napi_add() - initialize a NAPI context

 * @dev:  network device

 * @napi: NAPI context

 * @poll: polling function
@@ -2509,27 +2512,40 @@ static inline void *netdev_priv(const struct net_device *dev) 
 * netif_napi_add() must be used to initialize a NAPI context prior to calling

 * *any* of the other NAPI-related functions.

 */

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

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

static inline void

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

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

{

	netif_napi_add_weight(dev, napi, poll, weight);

}



static inline void

netif_napi_add_tx_weight(struct net_device *dev,

			 struct napi_struct *napi,

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

			 int weight)

{

	set_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state);

	netif_napi_add_weight(dev, napi, poll, weight);

}



#define netif_tx_napi_add netif_napi_add_tx_weight



/**

 *	netif_tx_napi_add - initialize a NAPI context

 * netif_napi_add_tx() - initialize a NAPI context to be used for Tx only

 * @dev:  network device

 * @napi: NAPI context

 * @poll: polling function

 *	@weight: default weight

 *

 * This variant of netif_napi_add() should be used from drivers using NAPI

 * to exclusively poll a TX queue.

 * This will avoid we add it into napi_hash[], thus polluting this hash table.

 */

static inline void netif_tx_napi_add(struct net_device *dev,

static inline void netif_napi_add_tx(struct net_device *dev,

				     struct napi_struct *napi,

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

				     int weight)

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

{

	set_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state);

	netif_napi_add(dev, napi, poll, weight);

	netif_napi_add_tx_weight(dev, napi, poll, NAPI_POLL_WEIGHT);

}



/**

net/core/dev.c

+3 −3
Original line number Diff line number Diff line
@@ -6303,7 +6303,7 @@ int dev_set_threaded(struct net_device *dev, bool threaded) 
}

EXPORT_SYMBOL(dev_set_threaded);



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

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

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

{

	if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
@@ -6337,7 +6337,7 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi, 
	if (dev->threaded && napi_kthread_create(napi))

		dev->threaded = 0;

}

EXPORT_SYMBOL(netif_napi_add);

EXPORT_SYMBOL(netif_napi_add_weight);



void napi_disable(struct napi_struct *n)

{