net/sched: mqprio: add extack messages for queue count validation

To make mqprio more user-friendly, create netlink extended ack messages
which say exactly what is wrong about the queue counts. This uses the
new support for printf-formatted extack messages.

Example:

$ tc qdisc add dev eno0 root handle 1: mqprio num_tc 8 \
	map 0 1 2 3 4 5 6 7 queues 3@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0
Error: sch_mqprio: TC 0 queues 3@0 overlap with TC 1 queues 1@1.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index 0f04b17588ca5d7950cb43b6d7f7916bbc3e9e6f..d2a2dc0684083135679bbb134c1d4972f263e81c 100644 (file)
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -36,28 +36,44 @@ static bool intervals_overlap(int a, int b, int c, int d)
 }
 
 static int mqprio_validate_queue_counts(struct net_device *dev,
-                                       const struct tc_mqprio_qopt *qopt)
+                                       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 ||
-                   !qopt->count[i] ||
-                   last > 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]))
+                                             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;
+                       }
                }
        }
 
@@ -65,7 +81,8 @@ static int mqprio_validate_queue_counts(struct net_device *dev,
 }
 
 static int mqprio_enable_offload(struct Qdisc *sch,
-                                const struct tc_mqprio_qopt *qopt)
+                                const struct tc_mqprio_qopt *qopt,
+                                struct netlink_ext_ack *extack)
 {
        struct tc_mqprio_qopt_offload mqprio = {.qopt = *qopt};
        struct mqprio_sched *priv = qdisc_priv(sch);
@@ -140,7 +157,8 @@ static void mqprio_destroy(struct Qdisc *sch)
 }
 
 static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt,
-                           const struct tc_mqprio_caps *caps)
+                           const struct tc_mqprio_caps *caps,
+                           struct netlink_ext_ack *extack)
 {
        int i, err;
 
@@ -168,7 +186,7 @@ static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt,
         * - request queue count validation here (and apply them)
         */
        if (!qopt->hw || caps->validate_queue_counts) {
-               err = mqprio_validate_queue_counts(dev, qopt);
+               err = mqprio_validate_queue_counts(dev, qopt, extack);
                if (err)
                        return err;
        }
@@ -296,7 +314,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt,
                                 &caps, sizeof(caps));
 
        qopt = nla_data(opt);
-       if (mqprio_parse_opt(dev, qopt, &caps))
+       if (mqprio_parse_opt(dev, qopt, &caps, extack))
                return -EINVAL;
 
        len = nla_len(opt) - NLA_ALIGN(sizeof(*qopt));
@@ -330,7 +348,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt,
         * supplied and verified mapping
         */
        if (qopt->hw) {
-               err = mqprio_enable_offload(sch, qopt);
+               err = mqprio_enable_offload(sch, qopt, extack);
                if (err)
                        return err;
        } else {