net: sched: restrict use of qstats qlen

This removes the use of qstats->qlen variable from the classifiers
and makes it an explicit argument to gnet_stats_copy_queue().

The qlen represents the qdisc queue length and is packed into
the qstats at the last moment before passnig to user space. By
handling it explicitely we avoid, in the percpu stats case, having
to figure out which per_cpu variable to put it in.

It would probably be best to remove it from qstats completely
but qstats is a user space ABI and can't be broken. A future
patch could make an internal only qstats structure that would
avoid having to allocate an additional u32 variable on the
Qdisc struct. This would make the qstats struct 128bits instead
of 128+32.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 4 deletions

diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index 907b12f..5835a93 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -275,17 +275,16 @@ static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
 				struct gnet_dump *d)
 {
 	struct drr_class *cl = (struct drr_class *)arg;
+	__u32 qlen = cl->qdisc->q.qlen;
 	struct tc_drr_stats xstats;
 
 	memset(&xstats, 0, sizeof(xstats));
-	if (cl->qdisc->q.qlen) {
+	if (qlen)
 		xstats.deficit = cl->deficit;
-		cl->qdisc->qstats.qlen = cl->qdisc->q.qlen;
-	}
 
 	if (gnet_stats_copy_basic(d, NULL, &cl->bstats) < 0 ||
 	    gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
-	    gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
+	    gnet_stats_copy_queue(d, &cl->qdisc->qstats, qlen) < 0)
 		return -1;
 
 	return gnet_stats_copy_app(d, &xstats, sizeof(xstats));