net: sched: convert qdisc linked list to hashtable

Convert the per-device linked list into a hashtable. The primary
motivation for this change is that currently, we're not tracking all the
qdiscs in hierarchy (e.g. excluding default qdiscs), as the lookup
performed over the linked list by qdisc_match_from_root() is rather
expensive.

The ultimate goal is to get rid of hidden qdiscs completely, which will
bring much more determinism in user experience.

Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 076df5360ba5..96e0b6cd964e 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -52,6 +52,7 @@
 #include <uapi/linux/netdevice.h>
 #include <uapi/linux/if_bonding.h>
 #include <uapi/linux/pkt_cls.h>
+#include <linux/hashtable.h>
 
 struct netpoll_info;
 struct device;
@@ -1800,6 +1801,9 @@ struct net_device {
         unsigned int            num_tx_queues;
         unsigned int            real_num_tx_queues;
         struct Qdisc            *qdisc;
+#ifdef CONFIG_NET_SCHED
+        DECLARE_HASHTABLE       (qdisc_hash, 4);
+#endif
         unsigned long           tx_queue_len;
         spinlock_t              tx_global_lock;
         int                     watchdog_timeo;