Merge branch 'net-sched-extack'

Alexander Aring says:

====================
net: sched: sch: introduce extack support

this patch series basically add support for extack in common qdisc handling.
Additional it adds extack pointer to common qdisc callback handling this
offers per qdisc implementation to setting the extack message for each
failure over netlink.

The extack message will be set deeper in qdisc functions but going not
deeper as net core api. For qdisc module callback handling, the extack
will not be set. This will be part of per qdisc extack handling.

I also want to prepare patches to handle extack per qdisc module...
so there will come a lot of more patches, just cut them down to make
it reviewable.

There are some above 80-chars width warnings, which I ignore because
it looks more ugly otherwise.

This patch-series based on patches by David Ahern which gave me some
hints how to deal with extack support.

Cc: David Ahern <dsahern@gmail.com>

changes since v4:
 - rebase on current net-next/master
 - fix several typos (also David Ahren to Ahern, I am sorry)
 - Add acked by Jamal

changes since v3:
 - remove patch 2/2 lib: nlattr: set extack msg if validate_nla fails since
   David Ahern has a better solution
 - Remove check on net admin permission since -EPERM indicates it already
 - Change rtab to "rate table" - this is what it's stands for
 - Fix cbs *not* support messages
 - Fix tcf block error message for allocation, allocation will be still there
   because there are multiple places which returns -ENOMEM
 - Finnally also took care about sch_atm, sorry somehow I forgot this one and
   I hope I didn't forgot any sch implementation to add new callback parameters

changes since v2:
 - add fix coding style patch to catch all checkpatch warnings
 - add patch for setting netlink extack msg if validate_nla fails
 - changes in handle generic qdisc errors
   - remove NL_SET_ERR_MSG from memory allocation errors
   - remove NL_SET_ERR_MSG from device not found
   - change STAB to table size
 - add various new patches to add extack support for common
   TC functions like qdisc_get_rtab, tcf_block_get, qdisc_alloc
   and qdisc_create_dflt - users which are interessted in the
   detailed error messages can assign extack, otherwise NULL.
 - Add sch_cbq as example for qdisc_ops callback: init,
   qdisc_class_ops callbacks: change and graft
 - Add sch_cbs as example for qdisc_ops callback: change
 - Add sch_drr as example for qdisc_class ops callbacks: tcf_block
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 120 insertions, 52 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 74c22b4e365e..3a3a1da6b071 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -393,13 +393,16 @@ static __u8 __detect_linklayer(struct tc_ratespec *r, __u32 *rtab)
 static struct qdisc_rate_table *qdisc_rtab_list;
 
 struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,
-					struct nlattr *tab)
+					struct nlattr *tab,
+					struct netlink_ext_ack *extack)
 {
 	struct qdisc_rate_table *rtab;
 
 	if (tab == NULL || r->rate == 0 || r->cell_log == 0 ||
-	    nla_len(tab) != TC_RTAB_SIZE)
+	    nla_len(tab) != TC_RTAB_SIZE) {
+		NL_SET_ERR_MSG(extack, "Invalid rate table parameters for searching");
 		return NULL;
+	}
 
 	for (rtab = qdisc_rtab_list; rtab; rtab = rtab->next) {
 		if (!memcmp(&rtab->rate, r, sizeof(struct tc_ratespec)) &&
@@ -418,6 +421,8 @@ struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,
 			r->linklayer = __detect_linklayer(r, rtab->data);
 		rtab->next = qdisc_rtab_list;
 		qdisc_rtab_list = rtab;
+	} else {
+		NL_SET_ERR_MSG(extack, "Failed to allocate new qdisc rate table");
 	}
 	return rtab;
 }
@@ -449,7 +454,8 @@ static const struct nla_policy stab_policy[TCA_STAB_MAX + 1] = {
 	[TCA_STAB_DATA] = { .type = NLA_BINARY },
 };
 
-static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt)
+static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt,
+					       struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[TCA_STAB_MAX + 1];
 	struct qdisc_size_table *stab;
@@ -458,23 +464,29 @@ static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt)
 	u16 *tab = NULL;
 	int err;
 
-	err = nla_parse_nested(tb, TCA_STAB_MAX, opt, stab_policy, NULL);
+	err = nla_parse_nested(tb, TCA_STAB_MAX, opt, stab_policy, extack);
 	if (err < 0)
 		return ERR_PTR(err);
-	if (!tb[TCA_STAB_BASE])
+	if (!tb[TCA_STAB_BASE]) {
+		NL_SET_ERR_MSG(extack, "Size table base attribute is missing");
 		return ERR_PTR(-EINVAL);
+	}
 
 	s = nla_data(tb[TCA_STAB_BASE]);
 
 	if (s->tsize > 0) {
-		if (!tb[TCA_STAB_DATA])
+		if (!tb[TCA_STAB_DATA]) {
+			NL_SET_ERR_MSG(extack, "Size table data attribute is missing");
 			return ERR_PTR(-EINVAL);
+		}
 		tab = nla_data(tb[TCA_STAB_DATA]);
 		tsize = nla_len(tb[TCA_STAB_DATA]) / sizeof(u16);
 	}
 
-	if (tsize != s->tsize || (!tab && tsize > 0))
+	if (tsize != s->tsize || (!tab && tsize > 0)) {
+		NL_SET_ERR_MSG(extack, "Invalid size of size table");
 		return ERR_PTR(-EINVAL);
+	}
 
 	list_for_each_entry(stab, &qdisc_stab_list, list) {
 		if (memcmp(&stab->szopts, s, sizeof(*s)))
@@ -669,7 +681,7 @@ int qdisc_class_hash_init(struct Qdisc_class_hash *clhash)
 	unsigned int size = 4;
 
 	clhash->hash = qdisc_class_hash_alloc(size);
-	if (clhash->hash == NULL)
+	if (!clhash->hash)
 		return -ENOMEM;
 	clhash->hashsize  = size;
 	clhash->hashmask  = size - 1;
@@ -899,7 +911,8 @@ static void notify_and_destroy(struct net *net, struct sk_buff *skb,
 
 static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 		       struct sk_buff *skb, struct nlmsghdr *n, u32 classid,
-		       struct Qdisc *new, struct Qdisc *old)
+		       struct Qdisc *new, struct Qdisc *old,
+		       struct netlink_ext_ack *extack)
 {
 	struct Qdisc *q = old;
 	struct net *net = dev_net(dev);
@@ -914,8 +927,10 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
 		    (new && new->flags & TCQ_F_INGRESS)) {
 			num_q = 1;
 			ingress = 1;
-			if (!dev_ingress_queue(dev))
+			if (!dev_ingress_queue(dev)) {
+				NL_SET_ERR_MSG(extack, "Device does not have an ingress queue");
 				return -ENOENT;
+			}
 		}
 
 		if (dev->flags & IFF_UP)
@@ -966,10 +981,13 @@ skip:
 		if (cops && cops->graft) {
 			unsigned long cl = cops->find(parent, classid);
 
-			if (cl)
-				err = cops->graft(parent, cl, new, &old);
-			else
+			if (cl) {
+				err = cops->graft(parent, cl, new, &old,
+						  extack);
+			} else {
+				NL_SET_ERR_MSG(extack, "Specified class not found");
 				err = -ENOENT;
+			}
 		}
 		if (!err)
 			notify_and_destroy(net, skb, n, classid, old, new);
@@ -990,7 +1008,8 @@ static struct lock_class_key qdisc_rx_lock;
 static struct Qdisc *qdisc_create(struct net_device *dev,
 				  struct netdev_queue *dev_queue,
 				  struct Qdisc *p, u32 parent, u32 handle,
-				  struct nlattr **tca, int *errp)
+				  struct nlattr **tca, int *errp,
+				  struct netlink_ext_ack *extack)
 {
 	int err;
 	struct nlattr *kind = tca[TCA_KIND];
@@ -1028,10 +1047,12 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 #endif
 
 	err = -ENOENT;
-	if (!ops)
+	if (!ops) {
+		NL_SET_ERR_MSG(extack, "Specified qdisc not found");
 		goto err_out;
+	}
 
-	sch = qdisc_alloc(dev_queue, ops);
+	sch = qdisc_alloc(dev_queue, ops, extack);
 	if (IS_ERR(sch)) {
 		err = PTR_ERR(sch);
 		goto err_out2;
@@ -1069,7 +1090,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 	}
 
 	if (ops->init) {
-		err = ops->init(sch, tca[TCA_OPTIONS]);
+		err = ops->init(sch, tca[TCA_OPTIONS], extack);
 		if (err != 0)
 			goto err_out5;
 	}
@@ -1086,7 +1107,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 	}
 
 	if (tca[TCA_STAB]) {
-		stab = qdisc_get_stab(tca[TCA_STAB]);
+		stab = qdisc_get_stab(tca[TCA_STAB], extack);
 		if (IS_ERR(stab)) {
 			err = PTR_ERR(stab);
 			goto err_out4;
@@ -1097,8 +1118,10 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 		seqcount_t *running;
 
 		err = -EOPNOTSUPP;
-		if (sch->flags & TCQ_F_MQROOT)
+		if (sch->flags & TCQ_F_MQROOT) {
+			NL_SET_ERR_MSG(extack, "Cannot attach rate estimator to a multi-queue root qdisc");
 			goto err_out4;
+		}
 
 		if (sch->parent != TC_H_ROOT &&
 		    !(sch->flags & TCQ_F_INGRESS) &&
@@ -1113,8 +1136,10 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
 					NULL,
 					running,
 					tca[TCA_RATE]);
-		if (err)
+		if (err) {
+			NL_SET_ERR_MSG(extack, "Failed to generate new estimator");
 			goto err_out4;
+		}
 	}
 
 	qdisc_hash_add(sch, false);
@@ -1147,21 +1172,24 @@ err_out4:
 	goto err_out3;
 }
 
-static int qdisc_change(struct Qdisc *sch, struct nlattr **tca)
+static int qdisc_change(struct Qdisc *sch, struct nlattr **tca,
+			struct netlink_ext_ack *extack)
 {
 	struct qdisc_size_table *ostab, *stab = NULL;
 	int err = 0;
 
 	if (tca[TCA_OPTIONS]) {
-		if (!sch->ops->change)
+		if (!sch->ops->change) {
+			NL_SET_ERR_MSG(extack, "Change operation not supported by specified qdisc");
 			return -EINVAL;
-		err = sch->ops->change(sch, tca[TCA_OPTIONS]);
+		}
+		err = sch->ops->change(sch, tca[TCA_OPTIONS], extack);
 		if (err)
 			return err;
 	}
 
 	if (tca[TCA_STAB]) {
-		stab = qdisc_get_stab(tca[TCA_STAB]);
+		stab = qdisc_get_stab(tca[TCA_STAB], extack);
 		if (IS_ERR(stab))
 			return PTR_ERR(stab);
 	}
@@ -1259,8 +1287,10 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 		if (clid != TC_H_ROOT) {
 			if (TC_H_MAJ(clid) != TC_H_MAJ(TC_H_INGRESS)) {
 				p = qdisc_lookup(dev, TC_H_MAJ(clid));
-				if (!p)
+				if (!p) {
+					NL_SET_ERR_MSG(extack, "Failed to find qdisc with specified classid");
 					return -ENOENT;
+				}
 				q = qdisc_leaf(p, clid);
 			} else if (dev_ingress_queue(dev)) {
 				q = dev_ingress_queue(dev)->qdisc_sleeping;
@@ -1268,26 +1298,38 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 		} else {
 			q = dev->qdisc;
 		}
-		if (!q)
+		if (!q) {
+			NL_SET_ERR_MSG(extack, "Cannot find specified qdisc on specified device");
 			return -ENOENT;
+		}
 
-		if (tcm->tcm_handle && q->handle != tcm->tcm_handle)
+		if (tcm->tcm_handle && q->handle != tcm->tcm_handle) {
+			NL_SET_ERR_MSG(extack, "Invalid handle");
 			return -EINVAL;
+		}
 	} else {
 		q = qdisc_lookup(dev, tcm->tcm_handle);
-		if (!q)
+		if (!q) {
+			NL_SET_ERR_MSG(extack, "Failed to find qdisc with specified handle");
 			return -ENOENT;
+		}
 	}
 
-	if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], q->ops->id))
+	if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], q->ops->id)) {
+		NL_SET_ERR_MSG(extack, "Invalid qdisc name");
 		return -EINVAL;
+	}
 
 	if (n->nlmsg_type == RTM_DELQDISC) {
-		if (!clid)
+		if (!clid) {
+			NL_SET_ERR_MSG(extack, "Classid cannot be zero");
 			return -EINVAL;
-		if (q->handle == 0)
+		}
+		if (q->handle == 0) {
+			NL_SET_ERR_MSG(extack, "Cannot delete qdisc with handle of zero");
 			return -ENOENT;
-		err = qdisc_graft(dev, p, skb, n, clid, NULL, q);
+		}
+		err = qdisc_graft(dev, p, skb, n, clid, NULL, q, extack);
 		if (err != 0)
 			return err;
 	} else {
@@ -1333,8 +1375,10 @@ replay:
 		if (clid != TC_H_ROOT) {
 			if (clid != TC_H_INGRESS) {
 				p = qdisc_lookup(dev, TC_H_MAJ(clid));
-				if (!p)
+				if (!p) {
+					NL_SET_ERR_MSG(extack, "Failed to find specified qdisc");
 					return -ENOENT;
+				}
 				q = qdisc_leaf(p, clid);
 			} else if (dev_ingress_queue_create(dev)) {
 				q = dev_ingress_queue(dev)->qdisc_sleeping;
@@ -1349,21 +1393,33 @@ replay:
 
 		if (!q || !tcm->tcm_handle || q->handle != tcm->tcm_handle) {
 			if (tcm->tcm_handle) {
-				if (q && !(n->nlmsg_flags & NLM_F_REPLACE))
+				if (q && !(n->nlmsg_flags & NLM_F_REPLACE)) {
+					NL_SET_ERR_MSG(extack, "NLM_F_REPLACE needed to override");
 					return -EEXIST;
-				if (TC_H_MIN(tcm->tcm_handle))
+				}
+				if (TC_H_MIN(tcm->tcm_handle)) {
+					NL_SET_ERR_MSG(extack, "Invalid minor handle");
 					return -EINVAL;
+				}
 				q = qdisc_lookup(dev, tcm->tcm_handle);
-				if (!q)
+				if (!q) {
+					NL_SET_ERR_MSG(extack, "No qdisc found for specified handle");
 					goto create_n_graft;
-				if (n->nlmsg_flags & NLM_F_EXCL)
+				}
+				if (n->nlmsg_flags & NLM_F_EXCL) {
+					NL_SET_ERR_MSG(extack, "Exclusivity flag on, cannot override");
 					return -EEXIST;
+				}
 				if (tca[TCA_KIND] &&
-				    nla_strcmp(tca[TCA_KIND], q->ops->id))
+				    nla_strcmp(tca[TCA_KIND], q->ops->id)) {
+					NL_SET_ERR_MSG(extack, "Invalid qdisc name");
 					return -EINVAL;
+				}
 				if (q == p ||
-				    (p && check_loop(q, p, 0)))
+				    (p && check_loop(q, p, 0))) {
+					NL_SET_ERR_MSG(extack, "Qdisc parent/child loop detected");
 					return -ELOOP;
+				}
 				qdisc_refcount_inc(q);
 				goto graft;
 			} else {
@@ -1398,33 +1454,45 @@ replay:
 			}
 		}
 	} else {
-		if (!tcm->tcm_handle)
+		if (!tcm->tcm_handle) {
+			NL_SET_ERR_MSG(extack, "Handle cannot be zero");
 			return -EINVAL;
+		}
 		q = qdisc_lookup(dev, tcm->tcm_handle);
 	}
 
 	/* Change qdisc parameters */
-	if (!q)
+	if (!q) {
+		NL_SET_ERR_MSG(extack, "Specified qdisc not found");
 		return -ENOENT;
-	if (n->nlmsg_flags & NLM_F_EXCL)
+	}
+	if (n->nlmsg_flags & NLM_F_EXCL) {
+		NL_SET_ERR_MSG(extack, "Exclusivity flag on, cannot modify");
 		return -EEXIST;
-	if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], q->ops->id))
+	}
+	if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], q->ops->id)) {
+		NL_SET_ERR_MSG(extack, "Invalid qdisc name");
 		return -EINVAL;
-	err = qdisc_change(q, tca);
+	}
+	err = qdisc_change(q, tca, extack);
 	if (err == 0)
 		qdisc_notify(net, skb, n, clid, NULL, q);
 	return err;
 
 create_n_graft:
-	if (!(n->nlmsg_flags & NLM_F_CREATE))
+	if (!(n->nlmsg_flags & NLM_F_CREATE)) {
+		NL_SET_ERR_MSG(extack, "Qdisc not found. To create specify NLM_F_CREATE flag");
 		return -ENOENT;
+	}
 	if (clid == TC_H_INGRESS) {
-		if (dev_ingress_queue(dev))
+		if (dev_ingress_queue(dev)) {
 			q = qdisc_create(dev, dev_ingress_queue(dev), p,
 					 tcm->tcm_parent, tcm->tcm_parent,
-					 tca, &err);
-		else
+					 tca, &err, extack);
+		} else {
+			NL_SET_ERR_MSG(extack, "Cannot find ingress queue for specified device");
 			err = -ENOENT;
+		}
 	} else {
 		struct netdev_queue *dev_queue;
 
@@ -1437,7 +1505,7 @@ create_n_graft:
 
 		q = qdisc_create(dev, dev_queue, p,
 				 tcm->tcm_parent, tcm->tcm_handle,
-				 tca, &err);
+				 tca, &err, extack);
 	}
 	if (q == NULL) {
 		if (err == -EAGAIN)
@@ -1446,7 +1514,7 @@ create_n_graft:
 	}
 
 graft:
-	err = qdisc_graft(dev, p, skb, n, clid, q, NULL);
+	err = qdisc_graft(dev, p, skb, n, clid, q, NULL, extack);
 	if (err) {
 		if (q)
 			qdisc_destroy(q);
@@ -1698,7 +1766,7 @@ static void tc_bind_tclass(struct Qdisc *q, u32 portid, u32 clid,
 	cl = cops->find(q, portid);
 	if (!cl)
 		return;
-	block = cops->tcf_block(q, cl);
+	block = cops->tcf_block(q, cl, NULL);
 	if (!block)
 		return;
 	list_for_each_entry(chain, &block->chain_list, list) {
@@ -1845,7 +1913,7 @@ static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n,
 	new_cl = cl;
 	err = -EOPNOTSUPP;
 	if (cops->change)
-		err = cops->change(q, clid, portid, tca, &new_cl);
+		err = cops->change(q, clid, portid, tca, &new_cl, extack);
 	if (err == 0) {
 		tclass_notify(net, skb, n, q, new_cl, RTM_NEWTCLASS);
 		/* We just create a new class, need to do reverse binding. */