netlink: introduce type-checking attribute iteration

There are, especially with multi-attr arrays, many cases
of needing to iterate all attributes of a specific type
in a netlink message or a nested attribute. Add specific
macros to support that case.

Also convert many instances using this spatch:

    @@
    iterator nla_for_each_attr;
    iterator name nla_for_each_attr_type;
    identifier nla;
    expression head, len, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_attr(nla, head, len, rem)
    +nla_for_each_attr_type(nla, ATTR, head, len, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) == ATTR) {
     ...
    -}
     }

    @@
    identifier nla;
    iterator nla_for_each_nested;
    iterator name nla_for_each_nested_type;
    expression attr, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_nested(nla, attr, rem)
    +nla_for_each_nested_type(nla, ATTR, attr, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) == ATTR) {
     ...
    -}
     }

    @@
    iterator nla_for_each_attr;
    iterator name nla_for_each_attr_type;
    identifier nla;
    expression head, len, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_attr(nla, head, len, rem)
    +nla_for_each_attr_type(nla, ATTR, head, len, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) != ATTR) continue;
     ...
     }

    @@
    identifier nla;
    iterator nla_for_each_nested;
    iterator name nla_for_each_nested_type;
    expression attr, rem;
    expression ATTR;
    type T;
    identifier x;
    @@
    -nla_for_each_nested(nla, attr, rem)
    +nla_for_each_nested_type(nla, ATTR, attr, rem)
     {
    <... T x; ...>
    -if (nla_type(nla) != ATTR) continue;
     ...
     }

Although I had to undo one bad change this made, and
I also adjusted some other code for whitespace and to
use direct variable initialization now.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://lore.kernel.org/r/20240328203144.b5a6c895fb80.I1869b44767379f204998ff44dd239803f39c23e0@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -14581,12 +14581,9 @@ static int bnxt_bridge_setlink(struct net_device *dev, struct nlmsghdr *nlh,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
 		u16 mode;
 
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-
 		mode = nla_get_u16(attr);
 		if (mode == bp->br_mode)
 			break;

drivers/net/ethernet/emulex/benet/be_main.c

@@ -4982,10 +4982,7 @@ static int be_ndo_bridge_setlink(struct net_device *dev, struct nlmsghdr *nlh,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
 		mode = nla_get_u16(attr);
 		if (BE3_chip(adapter) && mode == BRIDGE_MODE_VEPA)
 			return -EOPNOTSUPP;

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -13108,13 +13108,9 @@ static int i40e_ndo_bridge_setlink(struct net_device *dev,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
-		__u16 mode;
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
+		__u16 mode = nla_get_u16(attr);
 
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-
-		mode = nla_get_u16(attr);
 		if ((mode != BRIDGE_MODE_VEPA) &&
 		    (mode != BRIDGE_MODE_VEB))
 			return -EINVAL;

drivers/net/ethernet/intel/ice/ice_main.c

@@ -7993,12 +7993,9 @@ ice_bridge_setlink(struct net_device *dev, struct nlmsghdr *nlh,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
-		__u16 mode;
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
+		__u16 mode = nla_get_u16(attr);
 
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-		mode = nla_get_u16(attr);
 		if (mode != BRIDGE_MODE_VEPA && mode != BRIDGE_MODE_VEB)
 			return -EINVAL;
 		/* Continue  if bridge mode is not being flipped */

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -10061,15 +10061,10 @@ static int ixgbe_ndo_bridge_setlink(struct net_device *dev,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
-		int status;
-		__u16 mode;
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
+		__u16 mode = nla_get_u16(attr);
+		int status = ixgbe_configure_bridge_mode(adapter, mode);
 
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-
-		mode = nla_get_u16(attr);
-		status = ixgbe_configure_bridge_mode(adapter, mode);
 		if (status)
 			return status;
 

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

@@ -4950,10 +4950,7 @@ static int mlx5e_bridge_setlink(struct net_device *dev, struct nlmsghdr *nlh,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
 		mode = nla_get_u16(attr);
 		if (mode > BRIDGE_MODE_VEPA)
 			return -EINVAL;

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -2289,10 +2289,7 @@ static int nfp_net_bridge_setlink(struct net_device *dev, struct nlmsghdr *nlh,
 	if (!br_spec)
 		return -EINVAL;
 
-	nla_for_each_nested(attr, br_spec, rem) {
-		if (nla_type(attr) != IFLA_BRIDGE_MODE)
-			continue;
-
+	nla_for_each_nested_type(attr, IFLA_BRIDGE_MODE, br_spec, rem) {
 		new_ctrl = nn->dp.ctrl;
 		mode = nla_get_u16(attr);
 		if (mode == BRIDGE_MODE_VEPA)

include/net/netlink.h

@@ -157,7 +157,11 @@
  *   nla_parse()			parse and validate stream of attrs
  *   nla_parse_nested()			parse nested attributes
  *   nla_for_each_attr()		loop over all attributes
+ *   nla_for_each_attr_type()		loop over all attributes with the
+ *					given type
  *   nla_for_each_nested()		loop over the nested attributes
+ *   nla_for_each_nested_type()		loop over the nested attributes with
+ *					the given type
  *=========================================================================
  */
 
@@ -2070,6 +2074,18 @@ static inline int nla_total_size_64bit(int payload)
 	     nla_ok(pos, rem); \
 	     pos = nla_next(pos, &(rem)))
 
+/**
+ * nla_for_each_attr_type - iterate over a stream of attributes
+ * @pos: loop counter, set to current attribute
+ * @type: required attribute type for @pos
+ * @head: head of attribute stream
+ * @len: length of attribute stream
+ * @rem: initialized to len, holds bytes currently remaining in stream
+ */
+#define nla_for_each_attr_type(pos, type, head, len, rem) \
+	nla_for_each_attr(pos, head, len, rem) \
+		if (nla_type(pos) == type)
+
 /**
  * nla_for_each_nested - iterate over nested attributes
  * @pos: loop counter, set to current attribute
@@ -2079,6 +2095,17 @@ static inline int nla_total_size_64bit(int payload)
 #define nla_for_each_nested(pos, nla, rem) \
 	nla_for_each_attr(pos, nla_data(nla), nla_len(nla), rem)
 
+/**
+ * nla_for_each_nested_type - iterate over nested attributes
+ * @pos: loop counter, set to current attribute
+ * @type: required attribute type for @pos
+ * @nla: attribute containing the nested attributes
+ * @rem: initialized to len, holds bytes currently remaining in stream
+ */
+#define nla_for_each_nested_type(pos, type, nla, rem) \
+	nla_for_each_nested(pos, nla, rem) \
+		if (nla_type(pos) == type)
+
 /**
  * nla_is_last - Test if attribute is last in stream
  * @nla: attribute to test

net/8021q/vlan_netlink.c

@@ -117,17 +117,15 @@ static int vlan_changelink(struct net_device *dev, struct nlattr *tb[],
 			return err;
 	}
 	if (data[IFLA_VLAN_INGRESS_QOS]) {
-		nla_for_each_nested(attr, data[IFLA_VLAN_INGRESS_QOS], rem) {
-			if (nla_type(attr) != IFLA_VLAN_QOS_MAPPING)
-				continue;
+		nla_for_each_nested_type(attr, IFLA_VLAN_QOS_MAPPING,
+					 data[IFLA_VLAN_INGRESS_QOS], rem) {
 			m = nla_data(attr);
 			vlan_dev_set_ingress_priority(dev, m->to, m->from);
 		}
 	}
 	if (data[IFLA_VLAN_EGRESS_QOS]) {
-		nla_for_each_nested(attr, data[IFLA_VLAN_EGRESS_QOS], rem) {
-			if (nla_type(attr) != IFLA_VLAN_QOS_MAPPING)
-				continue;
+		nla_for_each_nested_type(attr, IFLA_VLAN_QOS_MAPPING,
+					 data[IFLA_VLAN_EGRESS_QOS], rem) {
 			m = nla_data(attr);
 			err = vlan_dev_set_egress_priority(dev, m->from, m->to);
 			if (err)

net/core/bpf_sk_storage.c

@@ -496,27 +496,22 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs)
 	if (!bpf_capable())
 		return ERR_PTR(-EPERM);
 
-	nla_for_each_nested(nla, nla_stgs, rem) {
-		if (nla_type(nla) == SK_DIAG_BPF_STORAGE_REQ_MAP_FD) {
-			if (nla_len(nla) != sizeof(u32))
-				return ERR_PTR(-EINVAL);
-			nr_maps++;
-		}
+	nla_for_each_nested_type(nla, SK_DIAG_BPF_STORAGE_REQ_MAP_FD,
+				 nla_stgs, rem) {
+		if (nla_len(nla) != sizeof(u32))
+			return ERR_PTR(-EINVAL);
+		nr_maps++;
 	}
 
 	diag = kzalloc(struct_size(diag, maps, nr_maps), GFP_KERNEL);
 	if (!diag)
 		return ERR_PTR(-ENOMEM);
 
-	nla_for_each_nested(nla, nla_stgs, rem) {
-		struct bpf_map *map;
-		int map_fd;
-
-		if (nla_type(nla) != SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
-			continue;
+	nla_for_each_nested_type(nla, SK_DIAG_BPF_STORAGE_REQ_MAP_FD,
+				 nla_stgs, rem) {
+		int map_fd = nla_get_u32(nla);
+		struct bpf_map *map = bpf_map_get(map_fd);
 
-		map_fd = nla_get_u32(nla);
-		map = bpf_map_get(map_fd);
 		if (IS_ERR(map)) {
 			err = PTR_ERR(map);
 			goto err_free;

net/core/rtnetlink.c

@@ -5245,15 +5245,14 @@ static int rtnl_bridge_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
 
 	br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
 	if (br_spec) {
-		nla_for_each_nested(attr, br_spec, rem) {
-			if (nla_type(attr) == IFLA_BRIDGE_FLAGS) {
-				if (nla_len(attr) < sizeof(flags))
-					return -EINVAL;
+		nla_for_each_nested_type(attr, IFLA_BRIDGE_FLAGS, br_spec,
+					 rem) {
+			if (nla_len(attr) < sizeof(flags))
+				return -EINVAL;
 
-				have_flags = true;
-				flags = nla_get_u16(attr);
-				break;
-			}
+			have_flags = true;
+			flags = nla_get_u16(attr);
+			break;
 		}
 	}
 

net/devlink/dev.c

@@ -1202,17 +1202,13 @@ static void __devlink_compat_running_version(struct devlink *devlink,
 	if (err)
 		goto free_msg;
 
-	nla_for_each_attr(nlattr, (void *)msg->data, msg->len, rem) {
+	nla_for_each_attr_type(nlattr, DEVLINK_ATTR_INFO_VERSION_RUNNING,
+			       (void *)msg->data, msg->len, rem) {
 		const struct nlattr *kv;
 		int rem_kv;
 
-		if (nla_type(nlattr) != DEVLINK_ATTR_INFO_VERSION_RUNNING)
-			continue;
-
-		nla_for_each_nested(kv, nlattr, rem_kv) {
-			if (nla_type(kv) != DEVLINK_ATTR_INFO_VERSION_VALUE)
-				continue;
-
+		nla_for_each_nested_type(kv, DEVLINK_ATTR_INFO_VERSION_VALUE,
+					 nlattr, rem_kv) {
 			strlcat(buf, nla_data(kv), len);
 			strlcat(buf, " ", len);
 		}

net/sched/sch_mqprio.c

@@ -215,10 +215,8 @@ static int mqprio_parse_tc_entries(struct Qdisc *sch, struct nlattr *nlattr_opt,
 	for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++)
 		fp[tc] = priv->fp[tc];
 
-	nla_for_each_attr(n, nlattr_opt, nlattr_opt_len, rem) {
-		if (nla_type(n) != TCA_MQPRIO_TC_ENTRY)
-			continue;
-
+	nla_for_each_attr_type(n, TCA_MQPRIO_TC_ENTRY, nlattr_opt,
+			       nlattr_opt_len, rem) {
 		err = mqprio_parse_tc_entry(fp, n, &seen_tcs, extack);
 		if (err)
 			goto out;

net/sched/sch_taprio.c

@@ -1752,10 +1752,7 @@ static int taprio_parse_tc_entries(struct Qdisc *sch,
 		fp[tc] = q->fp[tc];
 	}
 
-	nla_for_each_nested(n, opt, rem) {
-		if (nla_type(n) != TCA_TAPRIO_ATTR_TC_ENTRY)
-			continue;
-
+	nla_for_each_nested_type(n, TCA_TAPRIO_ATTR_TC_ENTRY, opt, rem) {
 		err = taprio_parse_tc_entry(sch, n, max_sdu, fp, &seen_tcs,
 					    extack);
 		if (err)