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: Eric Dumazet <edumazet@google.com>
Cc: Allen Pais <allen.lkml@gmail.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index ac8c890a2657e35546ec51fe8b8a993a2bd0c91b..4ed32e6b020145afb015c3c07d2ec3a613f1311d 100644 (file)
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -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;
 }
 
 /* 

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 6c762457122fd0091cb0f2bf41bda73babc4ac12..d8fd8676fc724110630904909f64d7789f3a4b47 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -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)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 54c417244642a1445c618e6adf0e38b2d4f84565..49eae93d1489dc3513b41c237ca3f572e21ff203 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -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)