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, 41 deletions

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index c322a61eaeea..888a29ee1da6 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -26,6 +26,8 @@
 #include <net/sock.h>
 #include <net/tcp.h>
 
+#include "sch_mqprio_lib.h"
+
 static LIST_HEAD(taprio_list);
 
 #define TAPRIO_ALL_GATES_OPEN -1
@@ -924,7 +926,7 @@ static int taprio_parse_mqprio_opt(struct net_device *dev,
 				   struct netlink_ext_ack *extack,
 				   u32 taprio_flags)
 {
-	int i, j;
+	bool allow_overlapping_txqs = TXTIME_ASSIST_IS_ENABLED(taprio_flags);
 
 	if (!qopt && !dev->num_tc) {
 		NL_SET_ERR_MSG(extack, "'mqprio' configuration is necessary");
@@ -937,52 +939,17 @@ static int taprio_parse_mqprio_opt(struct net_device *dev,
 	if (dev->num_tc)
 		return 0;
 
-	/* Verify num_tc is not out of max range */
-	if (qopt->num_tc > TC_MAX_QUEUE) {
-		NL_SET_ERR_MSG(extack, "Number of traffic classes is outside valid range");
-		return -EINVAL;
-	}
-
 	/* taprio imposes that traffic classes map 1:n to tx queues */
 	if (qopt->num_tc > dev->num_tx_queues) {
 		NL_SET_ERR_MSG(extack, "Number of traffic classes is greater than number of HW queues");
 		return -EINVAL;
 	}
 
-	/* Verify priority mapping uses valid tcs */
-	for (i = 0; i <= TC_BITMASK; i++) {
-		if (qopt->prio_tc_map[i] >= qopt->num_tc) {
-			NL_SET_ERR_MSG(extack, "Invalid traffic class in priority to traffic class mapping");
-			return -EINVAL;
-		}
-	}
-
-	for (i = 0; i < qopt->num_tc; i++) {
-		unsigned int last = qopt->offset[i] + qopt->count[i];
-
-		/* 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->num_tx_queues ||
-		    !qopt->count[i] ||
-		    last > dev->real_num_tx_queues) {
-			NL_SET_ERR_MSG(extack, "Invalid queue in traffic class to queue mapping");
-			return -EINVAL;
-		}
-
-		if (TXTIME_ASSIST_IS_ENABLED(taprio_flags))
-			continue;
-
-		/* Verify that the offset and counts do not overlap */
-		for (j = i + 1; j < qopt->num_tc; j++) {
-			if (last > qopt->offset[j]) {
-				NL_SET_ERR_MSG(extack, "Detected overlap in the traffic class to queue mapping");
-				return -EINVAL;
-			}
-		}
-	}
-
-	return 0;
+	/* For some reason, in txtime-assist mode, we allow TXQ ranges for
+	 * different TCs to overlap, and just validate the TXQ ranges.
+	 */
+	return mqprio_validate_qopt(dev, qopt, true, allow_overlapping_txqs,
+				    extack);
 }
 
 static int taprio_get_start_time(struct Qdisc *sch,