net/sched: taprio: centralize mqprio qopt validation

There is a lot of code in taprio which is "borrowed" from mqprio.
It makes sense to put a stop to the "borrowing" and start actually
reusing code.

Because taprio and mqprio are built as part of different kernel modules,
code reuse can only take place either by writing it as static inline
(limiting), putting it in sch_generic.o (not generic enough), or
creating a third auto-selectable kernel module which only holds library
code. I opted for the third variant.

In a previous change, mqprio gained support for reverse TC:TXQ mappings,
something which taprio still denies. Make taprio use the same validation
logic so that it supports this configuration as well.

The taprio code didn't enforce TXQ overlaps in txtime-assist mode and
that looks intentional, even if I've no idea why that might be. Preserve
that, but add a comment.

There isn't any dedicated MAINTAINERS entry for mqprio, so nothing to
update there.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 69 deletions

diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index d2a2dc068408..9303d2a1e840 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -17,6 +17,8 @@
 #include <net/sch_generic.h>
 #include <net/pkt_cls.h>
 
+#include "sch_mqprio_lib.h"
+
 struct mqprio_sched {
 	struct Qdisc		**qdiscs;
 	u16 mode;
@@ -27,59 +29,6 @@ struct mqprio_sched {
 	u64 max_rate[TC_QOPT_MAX_QUEUE];
 };
 
-/* Returns true if the intervals [a, b) and [c, d) overlap. */
-static bool intervals_overlap(int a, int b, int c, int d)
-{
-	int left = max(a, c), right = min(b, d);
-
-	return left < right;
-}
-
-static int mqprio_validate_queue_counts(struct net_device *dev,
-					const struct tc_mqprio_qopt *qopt,
-					struct netlink_ext_ack *extack)
-{
-	int i, j;
-
-	for (i = 0; i < qopt->num_tc; i++) {
-		unsigned int last = qopt->offset[i] + qopt->count[i];
-
-		if (!qopt->count[i]) {
-			NL_SET_ERR_MSG_FMT_MOD(extack, "No queues for TC %d",
-					       i);
-			return -EINVAL;
-		}
-
-		/* Verify the queue count is in tx range being equal to the
-		 * real_num_tx_queues indicates the last queue is in use.
-		 */
-		if (qopt->offset[i] >= dev->real_num_tx_queues ||
-		    last > dev->real_num_tx_queues) {
-			NL_SET_ERR_MSG_FMT_MOD(extack,
-					       "Queues %d:%d for TC %d exceed the %d TX queues available",
-					       qopt->count[i], qopt->offset[i],
-					       i, dev->real_num_tx_queues);
-			return -EINVAL;
-		}
-
-		/* Verify that the offset and counts do not overlap */
-		for (j = i + 1; j < qopt->num_tc; j++) {
-			if (intervals_overlap(qopt->offset[i], last,
-					      qopt->offset[j],
-					      qopt->offset[j] +
-					      qopt->count[j])) {
-				NL_SET_ERR_MSG_FMT_MOD(extack,
-						       "TC %d queues %d@%d overlap with TC %d queues %d@%d",
-						       i, qopt->count[i], qopt->offset[i],
-						       j, qopt->count[j], qopt->offset[j]);
-				return -EINVAL;
-			}
-		}
-	}
-
-	return 0;
-}
-
 static int mqprio_enable_offload(struct Qdisc *sch,
 				 const struct tc_mqprio_qopt *qopt,
 				 struct netlink_ext_ack *extack)
@@ -160,17 +109,7 @@ static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt,
 			    const struct tc_mqprio_caps *caps,
 			    struct netlink_ext_ack *extack)
 {
-	int i, err;
-
-	/* Verify num_tc is not out of max range */
-	if (qopt->num_tc > TC_MAX_QUEUE)
-		return -EINVAL;
-
-	/* Verify priority mapping uses valid tcs */
-	for (i = 0; i < TC_BITMASK + 1; i++) {
-		if (qopt->prio_tc_map[i] >= qopt->num_tc)
-			return -EINVAL;
-	}
+	int err;
 
 	/* Limit qopt->hw to maximum supported offload value.  Drivers have
 	 * the option of overriding this later if they don't support the a
@@ -185,11 +124,11 @@ static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt,
 	 * - validate the provided queue counts by itself (and apply them)
 	 * - request queue count validation here (and apply them)
 	 */
-	if (!qopt->hw || caps->validate_queue_counts) {
-		err = mqprio_validate_queue_counts(dev, qopt, extack);
-		if (err)
-			return err;
-	}
+	err = mqprio_validate_qopt(dev, qopt,
+				   !qopt->hw || caps->validate_queue_counts,
+				   false, extack);
+	if (err)
+		return err;
 
 	/* If ndo_setup_tc is not present then hardware doesn't support offload
 	 * and we should return an error.