[PATCHv3 net-next 14/14] net: sch: sch_drr: add extack support

[Alexander Aring]

This patch adds extack support for the drr qdisc implementation by
adding NL_SET_ERR_MSG in validation of user input.
Also it serves to illustrate a use case of how the infrastructure ops
api changes are to be used by individual qdiscs.

Cc: David Ahern <dsah...@gmail.com>
Signed-off-by: Alexander Aring <ar...@mojatatu.com>
---
 net/sched/sch_drr.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index bf638ce57c50..e0b0cf8a9939 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -74,17 +74,21 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, 
u32 parentid,
        u32 quantum;
        int err;
 
-       if (!opt)
+       if (!opt) {
+               NL_SET_ERR_MSG(extack, "DRR options are required for this 
operation");
                return -EINVAL;
+       }
 
-       err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy, NULL);
+       err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy, extack);
        if (err < 0)
                return err;
 
        if (tb[TCA_DRR_QUANTUM]) {
                quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
-               if (quantum == 0)
+               if (quantum == 0) {
+                       NL_SET_ERR_MSG(extack, "Specified DRR quantum cannot be 
zero");
                        return -EINVAL;
+               }
        } else
                quantum = psched_mtu(qdisc_dev(sch));
 
@@ -95,8 +99,10 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, 
u32 parentid,
                                                    NULL,
                                                    
qdisc_root_sleeping_running(sch),
                                                    tca[TCA_RATE]);
-                       if (err)
+                       if (err) {
+                               NL_SET_ERR_MSG(extack, "Failed to replace 
estimator");
                                return err;
+                       }
                }
 
                sch_tree_lock(sch);
@@ -127,6 +133,7 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, 
u32 parentid,
                                            qdisc_root_sleeping_running(sch),
                                            tca[TCA_RATE]);
                if (err) {
+                       NL_SET_ERR_MSG(extack, "Failed to replace estimator");
                        qdisc_destroy(cl->qdisc);
                        kfree(cl);
                        return err;
@@ -179,8 +186,10 @@ static struct tcf_block *drr_tcf_block(struct Qdisc *sch, 
unsigned long cl,
 {
        struct drr_sched *q = qdisc_priv(sch);
 
-       if (cl)
+       if (cl) {
+               NL_SET_ERR_MSG(extack, "DRR classid must be zero");
                return NULL;
+       }
 
        return q->block;
 }
-- 
2.11.0