Commit 85496c9b authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'net-remove-some-rcu_bh-cruft' 

Eric Dumazet says:

====================
net: remove some rcu_bh cruft

There is no point using rcu_bh variant hoping to free objects faster,
especially hen using call_rcu() or kfree_rcu().

Disabling/enabling BH has a non-zero cost, and adds distracting
hot spots in kernel profiles eg. in ip6_xmit().
====================

Link: https://lore.kernel.org/r/20230321040115.787497-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents f6f4e739 fe602c87

include/linux/rtnetlink.h

+0 −10
Original line number Diff line number Diff line
@@ -61,16 +61,6 @@ static inline bool lockdep_rtnl_is_held(void) 
#define rcu_dereference_rtnl(p)					\

	rcu_dereference_check(p, lockdep_rtnl_is_held())



/**

 * rcu_dereference_bh_rtnl - rcu_dereference_bh with debug checking

 * @p: The pointer to read, prior to dereference

 *

 * Do an rcu_dereference_bh(p), but check caller either holds rcu_read_lock_bh()

 * or RTNL. Note : Please prefer rtnl_dereference() or rcu_dereference_bh()

 */

#define rcu_dereference_bh_rtnl(p)				\

	rcu_dereference_bh_check(p, lockdep_rtnl_is_held())



/**

 * rtnl_dereference - fetch RCU pointer when updates are prevented by RTNL

 * @p: The pointer to read, prior to dereferencing

include/net/arp.h

+4 −4
Original line number Diff line number Diff line
@@ -38,11 +38,11 @@ static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 
{

	struct neighbour *n;



	rcu_read_lock_bh();

	rcu_read_lock();

	n = __ipv4_neigh_lookup_noref(dev, key);

	if (n && !refcount_inc_not_zero(&n->refcnt))

		n = NULL;

	rcu_read_unlock_bh();

	rcu_read_unlock();



	return n;

}
@@ -51,10 +51,10 @@ static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key) 
{

	struct neighbour *n;



	rcu_read_lock_bh();

	rcu_read_lock();

	n = __ipv4_neigh_lookup_noref(dev, key);

	neigh_confirm(n);

	rcu_read_unlock_bh();

	rcu_read_unlock();

}



void arp_init(void);

include/net/ndisc.h

+6 −6
Original line number Diff line number Diff line
@@ -395,11 +395,11 @@ static inline struct neighbour *__ipv6_neigh_lookup(struct net_device *dev, cons 
{

	struct neighbour *n;



	rcu_read_lock_bh();

	rcu_read_lock();

	n = __ipv6_neigh_lookup_noref(dev, pkey);

	if (n && !refcount_inc_not_zero(&n->refcnt))

		n = NULL;

	rcu_read_unlock_bh();

	rcu_read_unlock();



	return n;

}
@@ -409,10 +409,10 @@ static inline void __ipv6_confirm_neigh(struct net_device *dev, 
{

	struct neighbour *n;



	rcu_read_lock_bh();

	rcu_read_lock();

	n = __ipv6_neigh_lookup_noref(dev, pkey);

	neigh_confirm(n);

	rcu_read_unlock_bh();

	rcu_read_unlock();

}



static inline void __ipv6_confirm_neigh_stub(struct net_device *dev,
@@ -420,10 +420,10 @@ static inline void __ipv6_confirm_neigh_stub(struct net_device *dev, 
{

	struct neighbour *n;



	rcu_read_lock_bh();

	rcu_read_lock();

	n = __ipv6_neigh_lookup_noref_stub(dev, pkey);

	neigh_confirm(n);

	rcu_read_unlock_bh();

	rcu_read_unlock();

}



/* uses ipv6_stub and is meant for use outside of IPv6 core */

include/net/neighbour.h

+3 −3
Original line number Diff line number Diff line
@@ -299,14 +299,14 @@ static inline struct neighbour *___neigh_lookup_noref( 
	const void *pkey,

	struct net_device *dev)

{

	struct neigh_hash_table *nht = rcu_dereference_bh(tbl->nht);

	struct neigh_hash_table *nht = rcu_dereference(tbl->nht);

	struct neighbour *n;

	u32 hash_val;



	hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);

	for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);

	for (n = rcu_dereference(nht->hash_buckets[hash_val]);

	     n != NULL;

	     n = rcu_dereference_bh(n->next)) {

	     n = rcu_dereference(n->next)) {

		if (n->dev == dev && key_eq(n, pkey))

			return n;

	}

include/net/nexthop.h

+3 −3
Original line number Diff line number Diff line
@@ -498,7 +498,7 @@ static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh) 
}



/* Variant of nexthop_fib6_nh().

 * Caller should either hold rcu_read_lock_bh(), or RTNL.

 * Caller should either hold rcu_read_lock(), or RTNL.

 */

static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh)

{
@@ -507,13 +507,13 @@ static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh) 
	if (nh->is_group) {

		struct nh_group *nh_grp;



		nh_grp = rcu_dereference_bh_rtnl(nh->nh_grp);

		nh_grp = rcu_dereference_rtnl(nh->nh_grp);

		nh = nexthop_mpath_select(nh_grp, 0);

		if (!nh)

			return NULL;

	}



	nhi = rcu_dereference_bh_rtnl(nh->nh_info);

	nhi = rcu_dereference_rtnl(nh->nh_info);

	if (nhi->family == AF_INET6)

		return &nhi->fib6_nh;