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>

1 files changed, 4 insertions, 8 deletions

diff --git a/net/devlink/dev.c b/net/devlink/dev.c
index 19dbf540748a..c609deb42e88 100644
--- a/net/devlink/dev.c
+++ b/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);
 		}