netdev - [RFC PATCH 1/2] net: netlink: add nla_get_*

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Message-ID: <20241024131807.0a6c07355832.I3df6aac71d38a5baa1c0a03d0c7e82d4395c030e@changeid>
Date: Thu, 24 Oct 2024 13:18:06 +0200
From: Johannes Berg <johannes@...solutions.net>
To: linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org
Cc: Johannes Berg <johannes.berg@...el.com>
Subject: [RFC PATCH 1/2] net: netlink: add nla_get_*_default() accessors

From: Johannes Berg <johannes.berg@...el.com>

There are quite a number of places that use patterns
such as

  if (attr)
     val = nla_get_u16(attr);
  else
     val = DEFAULT;

Add nla_get_u16_default() and friends like that to
not have to type this out all the time.

Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
 include/net/netlink.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/include/net/netlink.h b/include/net/netlink.h
index db6af207287c..b15bd0437945 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -142,6 +142,8 @@
  *   nla_get_flag(nla)			return 1 if flag is true
  *   nla_get_msecs(nla)			get payload for a msecs attribute
  *
+ *   The same functions also exist with _default().
+ *
  * Attribute Misc:
  *   nla_memcpy(dest, nla, count)	copy attribute into memory
  *   nla_memcmp(nla, data, size)	compare attribute with memory area
@@ -1867,6 +1869,31 @@ static inline unsigned long nla_get_msecs(const struct nlattr *nla)
 	return msecs_to_jiffies((unsigned long) msecs);
 }
 
+#define MAKE_NLA_GET_DEFAULT(tp, fn)			\
+static inline tp fn##_default(const struct nlattr *nla,	\
+			      tp defvalue)		\
+{							\
+	if (!nla)					\
+		return defvalue;			\
+	return n(nla);					\
+}
+
+MAKE_NLA_GET_DEFAULT(u8, nla_get_u8);
+MAKE_NLA_GET_DEFAULT(u16, nla_get_u16);
+MAKE_NLA_GET_DEFAULT(u32, nla_get_u32);
+MAKE_NLA_GET_DEFAULT(u64, nla_get_u64);
+MAKE_NLA_GET_DEFAULT(unsigned long, nla_get_msecs);
+MAKE_NLA_GET_DEFAULT(s8, nla_get_s8);
+MAKE_NLA_GET_DEFAULT(s16, nla_get_s16);
+MAKE_NLA_GET_DEFAULT(s32, nla_get_s32);
+MAKE_NLA_GET_DEFAULT(s64, nla_get_s64);
+MAKE_NLA_GET_DEFAULT(s16, nla_get_le16);
+MAKE_NLA_GET_DEFAULT(s32, nla_get_le32);
+MAKE_NLA_GET_DEFAULT(s64, nla_get_le64);
+MAKE_NLA_GET_DEFAULT(s16, nla_get_be16);
+MAKE_NLA_GET_DEFAULT(s32, nla_get_be32);
+MAKE_NLA_GET_DEFAULT(s64, nla_get_be64);
+
 /**
  * nla_get_in_addr - return payload of IPv4 address attribute
  * @nla: IPv4 address netlink attribute
-- 
2.47.0