net_sched: reduce fifo qdisc size

Because of various alignements [SLUB / qdisc], we use 512 bytes of
memory for one {p|b}fifo qdisc, instead of 256 bytes on 64bit arches and
192 bytes on 32bit ones.

Move the "u32 limit" inside "struct Qdisc" (no impact on other qdiscs)

Change qdisc_alloc(), first trying a regular allocation before an
oversized one.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 7 deletions

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 0da09d508737..a854cab03f1e 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -550,21 +550,25 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 {
         void *p;
         struct Qdisc *sch;
-        unsigned int size;
+        unsigned int size = QDISC_ALIGN(sizeof(*sch)) + ops->priv_size;
         int err = -ENOBUFS;
 
-        /* ensure that the Qdisc and the private data are 64-byte aligned */
-        size = QDISC_ALIGN(sizeof(*sch));
-        size += ops->priv_size + (QDISC_ALIGNTO - 1);
-
         p = kzalloc_node(size, 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;
-
+        /* 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;
+        }
         INIT_LIST_HEAD(&sch->list);
         skb_queue_head_init(&sch->q);
         spin_lock_init(&sch->busylock);