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Commit 56b17425 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: add rbnode to struct sk_buff 



Yaogong replaces TCP out of order receive queue by an RB tree.

As netem already does a private skb->{next/prev/tstamp} union
with a 'struct rb_node', lets do this in a cleaner way.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Yaogong Wang <wygivan@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8ce0c825

include/linux/skbuff.h

+13 −7
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/time.h>

#include <linux/bug.h>

#include <linux/cache.h>

#include <linux/rbtree.h>



#include <linux/atomic.h>

#include <asm/types.h>
@@ -440,6 +441,7 @@ static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1, 
 *	@next: Next buffer in list

 *	@prev: Previous buffer in list

 *	@tstamp: Time we arrived/left

 *	@rbnode: RB tree node, alternative to next/prev for netem/tcp

 *	@sk: Socket we are owned by

 *	@dev: Device we arrived on/are leaving by

 *	@cb: Control buffer. Free for use by every layer. Put private vars here
@@ -504,6 +506,8 @@ static inline u32 skb_mstamp_us_delta(const struct skb_mstamp *t1, 
 */



struct sk_buff {

	union {

		struct {

			/* These two members must be first. */

			struct sk_buff		*next;

			struct sk_buff		*prev;
@@ -512,7 +516,9 @@ struct sk_buff { 
				ktime_t		tstamp;

				struct skb_mstamp skb_mstamp;

			};



		};

		struct rb_node	rbnode; /* used in netem & tcp stack */

	};

	struct sock		*sk;

	struct net_device	*dev;

net/sched/sch_netem.c

+7 −20
Original line number Diff line number Diff line
@@ -139,33 +139,20 @@ struct netem_sched_data { 


/* Time stamp put into socket buffer control block

 * Only valid when skbs are in our internal t(ime)fifo queue.

 *

 * As skb->rbnode uses same storage than skb->next, skb->prev and skb->tstamp,

 * and skb->next & skb->prev are scratch space for a qdisc,

 * we save skb->tstamp value in skb->cb[] before destroying it.

 */

struct netem_skb_cb {

	psched_time_t	time_to_send;

	ktime_t		tstamp_save;

};



/* Because space in skb->cb[] is tight, netem overloads skb->next/prev/tstamp

 * to hold a rb_node structure.

 *

 * If struct sk_buff layout is changed, the following checks will complain.

 */

static struct rb_node *netem_rb_node(struct sk_buff *skb)

{

	BUILD_BUG_ON(offsetof(struct sk_buff, next) != 0);

	BUILD_BUG_ON(offsetof(struct sk_buff, prev) !=

		     offsetof(struct sk_buff, next) + sizeof(skb->next));

	BUILD_BUG_ON(offsetof(struct sk_buff, tstamp) !=

		     offsetof(struct sk_buff, prev) + sizeof(skb->prev));

	BUILD_BUG_ON(sizeof(struct rb_node) > sizeof(skb->next) +

					      sizeof(skb->prev) +

					      sizeof(skb->tstamp));

	return (struct rb_node *)&skb->next;

}



static struct sk_buff *netem_rb_to_skb(struct rb_node *rb)

{

	return (struct sk_buff *)rb;

	return container_of(rb, struct sk_buff, rbnode);

}



static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
@@ -403,8 +390,8 @@ static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) 
		else

			p = &parent->rb_left;

	}

	rb_link_node(netem_rb_node(nskb), parent, p);

	rb_insert_color(netem_rb_node(nskb), &q->t_root);

	rb_link_node(&nskb->rbnode, parent, p);

	rb_insert_color(&nskb->rbnode, &q->t_root);

	sch->q.qlen++;

}