Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 932bc4d7 authored by Julian Anastasov's avatar Julian Anastasov Committed by Pablo Neira Ayuso
Browse files

net: add skb_dst_set_noref_force 



Rename skb_dst_set_noref to __skb_dst_set_noref and
add force flag as suggested by David Miller. The new wrapper
skb_dst_set_noref_force will force dst entries that are not
cached to be attached as skb dst without taking reference
as long as provided dst is reclaimed after RCU grace period.

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off by: Hans Schillstrom <hans@schillstrom.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
parent e5c5d22e

include/linux/skbuff.h

+34 −1
Original line number Diff line number Diff line
@@ -575,7 +575,40 @@ static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst) 
	skb->_skb_refdst = (unsigned long)dst;

}



extern void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst);

extern void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst,

				bool force);



/**

 * skb_dst_set_noref - sets skb dst, hopefully, without taking reference

 * @skb: buffer

 * @dst: dst entry

 *

 * Sets skb dst, assuming a reference was not taken on dst.

 * If dst entry is cached, we do not take reference and dst_release

 * will be avoided by refdst_drop. If dst entry is not cached, we take

 * reference, so that last dst_release can destroy the dst immediately.

 */

static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)

{

	__skb_dst_set_noref(skb, dst, false);

}



/**

 * skb_dst_set_noref_force - sets skb dst, without taking reference

 * @skb: buffer

 * @dst: dst entry

 *

 * Sets skb dst, assuming a reference was not taken on dst.

 * No reference is taken and no dst_release will be called. While for

 * cached dsts deferred reclaim is a basic feature, for entries that are

 * not cached it is caller's job to guarantee that last dst_release for

 * provided dst happens when nobody uses it, eg. after a RCU grace period.

 */

static inline void skb_dst_set_noref_force(struct sk_buff *skb,

					   struct dst_entry *dst)

{

	__skb_dst_set_noref(skb, dst, true);

}



/**

 * skb_dst_is_noref - Test if skb dst isn't refcounted

net/core/dst.c

+5 −4
Original line number Diff line number Diff line
@@ -320,27 +320,28 @@ void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old) 
EXPORT_SYMBOL(__dst_destroy_metrics_generic);



/**

 * skb_dst_set_noref - sets skb dst, without a reference

 * __skb_dst_set_noref - sets skb dst, without a reference

 * @skb: buffer

 * @dst: dst entry

 * @force: if force is set, use noref version even for DST_NOCACHE entries

 *

 * Sets skb dst, assuming a reference was not taken on dst

 * skb_dst_drop() should not dst_release() this dst

 */

void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst)

void __skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst, bool force)

{

	WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held());

	/* If dst not in cache, we must take a reference, because

	 * dst_release() will destroy dst as soon as its refcount becomes zero

	 */

	if (unlikely(dst->flags & DST_NOCACHE)) {

	if (unlikely((dst->flags & DST_NOCACHE) && !force)) {

		dst_hold(dst);

		skb_dst_set(skb, dst);

	} else {

		skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF;

	}

}

EXPORT_SYMBOL(skb_dst_set_noref);

EXPORT_SYMBOL(__skb_dst_set_noref);



/* Dirty hack. We did it in 2.2 (in __dst_free),

 * we have _very_ good reasons not to repeat