Commit 49052941 authored by Guillaume Nault's avatar Guillaume Nault Committed by David S. Miller
Browse files

netns: Remove __peernet2id_alloc() 



__peernet2id_alloc() was used for both plain lookups and for netns ID
allocations (depending the value of '*alloc'). Let's separate lookups
from allocations instead. That is, integrate the lookup code into
__peernet2id() and make peernet2id_alloc() responsible for allocating
new netns IDs when necessary.

This makes it clear that __peernet2id() doesn't modify the idr and
prepares the code for lockless lookups.

Also, mark the 'net' argument of __peernet2id() as 'const', since we're
modifying this line.

Signed-off-by: default avatarGuillaume Nault <gnault@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 62140036

net/core/net_namespace.c

+23 −32
Original line number Diff line number Diff line
@@ -211,16 +211,10 @@ static int net_eq_idr(int id, void *net, void *peer) 
	return 0;

}



/* Should be called with nsid_lock held. If a new id is assigned, the bool alloc

 * is set to true, thus the caller knows that the new id must be notified via

 * rtnl.

 */

static int __peernet2id_alloc(struct net *net, struct net *peer, bool *alloc)

/* Should be called with nsid_lock held. */

static int __peernet2id(const struct net *net, struct net *peer)

{

	int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);

	bool alloc_it = *alloc;



	*alloc = false;



	/* Magic value for id 0. */

	if (id == NET_ID_ZERO)
@@ -228,23 +222,9 @@ static int __peernet2id_alloc(struct net *net, struct net *peer, bool *alloc) 
	if (id > 0)

		return id;



	if (alloc_it) {

		id = alloc_netid(net, peer, -1);

		*alloc = true;

		return id >= 0 ? id : NETNSA_NSID_NOT_ASSIGNED;

	}



	return NETNSA_NSID_NOT_ASSIGNED;

}



/* should be called with nsid_lock held */

static int __peernet2id(struct net *net, struct net *peer)

{

	bool no = false;



	return __peernet2id_alloc(net, peer, &no);

}



static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,

			      struct nlmsghdr *nlh, gfp_t gfp);

/* This function returns the id of a peer netns. If no id is assigned, one will
@@ -252,26 +232,37 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid, 
 */

int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)

{

	bool alloc = false, alive = false;

	int id;



	if (refcount_read(&net->count) == 0)

		return NETNSA_NSID_NOT_ASSIGNED;



	spin_lock_bh(&net->nsid_lock);

	/*

	 * When peer is obtained from RCU lists, we may race with

	id = __peernet2id(net, peer);

	if (id >= 0) {

		spin_unlock_bh(&net->nsid_lock);

		return id;

	}



	/* When peer is obtained from RCU lists, we may race with

	 * its cleanup. Check whether it's alive, and this guarantees

	 * we never hash a peer back to net->netns_ids, after it has

	 * just been idr_remove()'d from there in cleanup_net().

	 */

	if (maybe_get_net(peer))

		alive = alloc = true;

	id = __peernet2id_alloc(net, peer, &alloc);

	if (!maybe_get_net(peer)) {

		spin_unlock_bh(&net->nsid_lock);

	if (alloc && id >= 0)

		rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);

	if (alive)

		return NETNSA_NSID_NOT_ASSIGNED;

	}



	id = alloc_netid(net, peer, -1);

	spin_unlock_bh(&net->nsid_lock);



	put_net(peer);

	if (id < 0)

		return NETNSA_NSID_NOT_ASSIGNED;



	rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);



	return id;

}

EXPORT_SYMBOL_GPL(peernet2id_alloc);

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