Revert "net: dev: introduce support for sch BYPASS for lockless qdisc"

[ Upstream commit 379349e9bc3b42b8b2f8f7a03f64a97623fff323 ]

This reverts commit ba27b4cdaaa66561aaedb2101876e563738d36fe

Ahmed reported ouf-of-order issues bisected to commit ba27b4cdaaa6
("net: dev: introduce support for sch BYPASS for lockless qdisc").
I can't find any working solution other than a plain revert.

This will introduce some minor performance regressions for
pfifo_fast qdisc. I plan to address them in net-next with more
indirect call wrapper boilerplate for qdiscs.

Reported-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Fixes: ba27b4cdaaa6 ("net: dev: introduce support for sch BYPASS for lockless qdisc")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/dev.c b/net/core/dev.c
index 466f2e4144b090ac6855b24d6a2ff34b6a081641..8461f4eba716fe08843ef95d614136d02ac26550 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3607,26 +3607,8 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q,
        qdisc_calculate_pkt_len(skb, q);
 
        if (q->flags & TCQ_F_NOLOCK) {
-               if ((q->flags & TCQ_F_CAN_BYPASS) && READ_ONCE(q->empty) &&
-                   qdisc_run_begin(q)) {
-                       if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED,
-                                             &q->state))) {
-                               __qdisc_drop(skb, &to_free);
-                               rc = NET_XMIT_DROP;
-                               goto end_run;
-                       }
-                       qdisc_bstats_cpu_update(q, skb);
-
-                       rc = NET_XMIT_SUCCESS;
-                       if (sch_direct_xmit(skb, q, dev, txq, NULL, true))
-                               __qdisc_run(q);
-
-end_run:
-                       qdisc_run_end(q);
-               } else {
-                       rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK;
-                       qdisc_run(q);
-               }
+               rc = q->enqueue(skb, q, &to_free) & NET_XMIT_MASK;
+               qdisc_run(q);
 
                if (unlikely(to_free))
                        kfree_skb_list(to_free);