Commit 846e463a authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net/sched: get rid of qdisc->padded 



kmalloc() of sufficiently big portion of memory is cache-aligned
in regular conditions. If some debugging options are used,
there is no reason qdisc structures would need 64-byte alignment
if most other kernel structures are not aligned.

This get rid of QDISC_ALIGN and QDISC_ALIGNTO.

Addition of privdata field will help implementing
the reverse of qdisc_priv() and documents where
the private data is.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Allen Pais <allen.lkml@gmail.com>
Acked-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 036dfd83

include/net/pkt_sched.h

+1 −4
Original line number Diff line number Diff line
@@ -19,12 +19,9 @@ struct qdisc_walker { 
	int	(*fn)(struct Qdisc *, unsigned long cl, struct qdisc_walker *);

};



#define QDISC_ALIGNTO		64

#define QDISC_ALIGN(len)	(((len) + QDISC_ALIGNTO-1) & ~(QDISC_ALIGNTO-1))



static inline void *qdisc_priv(struct Qdisc *q)

{

	return (char *) q + QDISC_ALIGN(sizeof(struct Qdisc));

	return &q->privdata;

}



/*

include/net/sch_generic.h

+4 −1
Original line number Diff line number Diff line
@@ -91,7 +91,7 @@ struct Qdisc { 
	struct net_rate_estimator __rcu *rate_est;

	struct gnet_stats_basic_cpu __percpu *cpu_bstats;

	struct gnet_stats_queue	__percpu *cpu_qstats;

	int			padded;

	int			pad;

	refcount_t		refcnt;



	/*
@@ -112,6 +112,9 @@ struct Qdisc { 
	/* for NOLOCK qdisc, true if there are no enqueued skbs */

	bool			empty;

	struct rcu_head		rcu;



	/* private data */

	long privdata[] ____cacheline_aligned;

};



static inline void qdisc_refcount_inc(struct Qdisc *qdisc)

net/sched/sch_generic.c

+5 −18
Original line number Diff line number Diff line
@@ -802,9 +802,8 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, 
			  const struct Qdisc_ops *ops,

			  struct netlink_ext_ack *extack)

{

	void *p;

	struct Qdisc *sch;

	unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;

	unsigned int size = sizeof(*sch) + ops->priv_size;

	int err = -ENOBUFS;

	struct net_device *dev;
@@ -815,22 +814,10 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, 
	}



	dev = dev_queue->dev;

	p = kzalloc_node(size, GFP_KERNEL,

			 netdev_queue_numa_node_read(dev_queue));

	sch = kzalloc_node(size, GFP_KERNEL, netdev_queue_numa_node_read(dev_queue));



	if (!p)

	if (!sch)

		goto errout;

	sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);

	/* if we got non aligned memory, ask more and do alignment ourself */

	if (sch != p) {

		kfree(p);

		p = kzalloc_node(size + QDISC_ALIGNTO - 1, GFP_KERNEL,

				 netdev_queue_numa_node_read(dev_queue));

		if (!p)

			goto errout;

		sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);

		sch->padded = (char *) sch - (char *) p;

	}

	__skb_queue_head_init(&sch->gso_skb);

	__skb_queue_head_init(&sch->skb_bad_txq);

	qdisc_skb_head_init(&sch->q);
@@ -873,7 +860,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, 


	return sch;

errout1:

	kfree(p);

	kfree(sch);

errout:

	return ERR_PTR(err);

}
@@ -941,7 +928,7 @@ void qdisc_free(struct Qdisc *qdisc) 
		free_percpu(qdisc->cpu_qstats);

	}



	kfree((char *) qdisc - qdisc->padded);

	kfree(qdisc);

}



static void qdisc_free_cb(struct rcu_head *head)

CRA Git | Maintained and supported by SUSTech CRA and CCSE