net: netlink: add nla_get_*_default() accessors

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.

Acked-by: Toke Høiland-Jørgensen <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>
Signed-off-by: Johannes Berg <[email protected]>
Link: https://patch.msgid.link/20241108114145.acd2aadb03ac.I3df6aac71d38a5baa1c0a03d0c7e82d4395c030e@changeid
Signed-off-by: Jakub Kicinski <[email protected]>

Author: jmberg-intel

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
@@ -1695,6 +1697,20 @@ static inline u32 nla_get_u32(const struct nlattr *nla)
 	return *(u32 *) nla_data(nla);
 }
 
+/**
+ * nla_get_u32_default - return payload of u32 attribute or default
+ * @nla: u32 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline u32 nla_get_u32_default(const struct nlattr *nla, u32 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_u32(nla);
+}
+
 /**
  * nla_get_be32 - return payload of __be32 attribute
  * @nla: __be32 netlink attribute
@@ -1704,6 +1720,21 @@ static inline __be32 nla_get_be32(const struct nlattr *nla)
 	return *(__be32 *) nla_data(nla);
 }
 
+/**
+ * nla_get_be32_default - return payload of be32 attribute or default
+ * @nla: __be32 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __be32 nla_get_be32_default(const struct nlattr *nla,
+					  __be32 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_be32(nla);
+}
+
 /**
  * nla_get_le32 - return payload of __le32 attribute
  * @nla: __le32 netlink attribute
@@ -1713,6 +1744,21 @@ static inline __le32 nla_get_le32(const struct nlattr *nla)
 	return *(__le32 *) nla_data(nla);
 }
 
+/**
+ * nla_get_le32_default - return payload of le32 attribute or default
+ * @nla: __le32 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __le32 nla_get_le32_default(const struct nlattr *nla,
+					  __le32 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_le32(nla);
+}
+
 /**
  * nla_get_u16 - return payload of u16 attribute
  * @nla: u16 netlink attribute
@@ -1722,6 +1768,20 @@ static inline u16 nla_get_u16(const struct nlattr *nla)
 	return *(u16 *) nla_data(nla);
 }
 
+/**
+ * nla_get_u16_default - return payload of u16 attribute or default
+ * @nla: u16 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline u16 nla_get_u16_default(const struct nlattr *nla, u16 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_u16(nla);
+}
+
 /**
  * nla_get_be16 - return payload of __be16 attribute
  * @nla: __be16 netlink attribute
@@ -1731,6 +1791,21 @@ static inline __be16 nla_get_be16(const struct nlattr *nla)
 	return *(__be16 *) nla_data(nla);
 }
 
+/**
+ * nla_get_be16_default - return payload of be16 attribute or default
+ * @nla: __be16 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __be16 nla_get_be16_default(const struct nlattr *nla,
+					  __be16 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_be16(nla);
+}
+
 /**
  * nla_get_le16 - return payload of __le16 attribute
  * @nla: __le16 netlink attribute
@@ -1740,6 +1815,21 @@ static inline __le16 nla_get_le16(const struct nlattr *nla)
 	return *(__le16 *) nla_data(nla);
 }
 
+/**
+ * nla_get_le16_default - return payload of le16 attribute or default
+ * @nla: __le16 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __le16 nla_get_le16_default(const struct nlattr *nla,
+					  __le16 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_le16(nla);
+}
+
 /**
  * nla_get_u8 - return payload of u8 attribute
  * @nla: u8 netlink attribute
@@ -1749,6 +1839,20 @@ static inline u8 nla_get_u8(const struct nlattr *nla)
 	return *(u8 *) nla_data(nla);
 }
 
+/**
+ * nla_get_u8_default - return payload of u8 attribute or default
+ * @nla: u8 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline u8 nla_get_u8_default(const struct nlattr *nla, u8 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_u8(nla);
+}
+
 /**
  * nla_get_u64 - return payload of u64 attribute
  * @nla: u64 netlink attribute
@@ -1762,6 +1866,20 @@ static inline u64 nla_get_u64(const struct nlattr *nla)
 	return tmp;
 }
 
+/**
+ * nla_get_u64_default - return payload of u64 attribute or default
+ * @nla: u64 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline u64 nla_get_u64_default(const struct nlattr *nla, u64 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_u64(nla);
+}
+
 /**
  * nla_get_uint - return payload of uint attribute
  * @nla: uint netlink attribute
@@ -1773,6 +1891,20 @@ static inline u64 nla_get_uint(const struct nlattr *nla)
 	return nla_get_u64(nla);
 }
 
+/**
+ * nla_get_uint_default - return payload of uint attribute or default
+ * @nla: uint netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline u64 nla_get_uint_default(const struct nlattr *nla, u64 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_uint(nla);
+}
+
 /**
  * nla_get_be64 - return payload of __be64 attribute
  * @nla: __be64 netlink attribute
@@ -1786,6 +1918,21 @@ static inline __be64 nla_get_be64(const struct nlattr *nla)
 	return tmp;
 }
 
+/**
+ * nla_get_be64_default - return payload of be64 attribute or default
+ * @nla: __be64 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __be64 nla_get_be64_default(const struct nlattr *nla,
+					  __be64 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_be64(nla);
+}
+
 /**
  * nla_get_le64 - return payload of __le64 attribute
  * @nla: __le64 netlink attribute
@@ -1795,6 +1942,21 @@ static inline __le64 nla_get_le64(const struct nlattr *nla)
 	return *(__le64 *) nla_data(nla);
 }
 
+/**
+ * nla_get_le64_default - return payload of le64 attribute or default
+ * @nla: __le64 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __le64 nla_get_le64_default(const struct nlattr *nla,
+					  __le64 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_le64(nla);
+}
+
 /**
  * nla_get_s32 - return payload of s32 attribute
  * @nla: s32 netlink attribute
@@ -1804,6 +1966,20 @@ static inline s32 nla_get_s32(const struct nlattr *nla)
 	return *(s32 *) nla_data(nla);
 }
 
+/**
+ * nla_get_s32_default - return payload of s32 attribute or default
+ * @nla: s32 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline s32 nla_get_s32_default(const struct nlattr *nla, s32 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_s32(nla);
+}
+
 /**
  * nla_get_s16 - return payload of s16 attribute
  * @nla: s16 netlink attribute
@@ -1813,6 +1989,20 @@ static inline s16 nla_get_s16(const struct nlattr *nla)
 	return *(s16 *) nla_data(nla);
 }
 
+/**
+ * nla_get_s16_default - return payload of s16 attribute or default
+ * @nla: s16 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline s16 nla_get_s16_default(const struct nlattr *nla, s16 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_s16(nla);
+}
+
 /**
  * nla_get_s8 - return payload of s8 attribute
  * @nla: s8 netlink attribute
@@ -1822,6 +2012,20 @@ static inline s8 nla_get_s8(const struct nlattr *nla)
 	return *(s8 *) nla_data(nla);
 }
 
+/**
+ * nla_get_s8_default - return payload of s8 attribute or default
+ * @nla: s8 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline s8 nla_get_s8_default(const struct nlattr *nla, s8 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_s8(nla);
+}
+
 /**
  * nla_get_s64 - return payload of s64 attribute
  * @nla: s64 netlink attribute
@@ -1835,6 +2039,20 @@ static inline s64 nla_get_s64(const struct nlattr *nla)
 	return tmp;
 }
 
+/**
+ * nla_get_s64_default - return payload of s64 attribute or default
+ * @nla: s64 netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline s64 nla_get_s64_default(const struct nlattr *nla, s64 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_s64(nla);
+}
+
 /**
  * nla_get_sint - return payload of uint attribute
  * @nla: uint netlink attribute
@@ -1846,6 +2064,20 @@ static inline s64 nla_get_sint(const struct nlattr *nla)
 	return nla_get_s64(nla);
 }
 
+/**
+ * nla_get_sint_default - return payload of sint attribute or default
+ * @nla: sint netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline s64 nla_get_sint_default(const struct nlattr *nla, s64 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_sint(nla);
+}
+
 /**
  * nla_get_flag - return payload of flag attribute
  * @nla: flag netlink attribute
@@ -1868,6 +2100,21 @@ static inline unsigned long nla_get_msecs(const struct nlattr *nla)
 	return msecs_to_jiffies((unsigned long) msecs);
 }
 
+/**
+ * nla_get_msecs_default - return payload of msecs attribute or default
+ * @nla: msecs netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline unsigned long nla_get_msecs_default(const struct nlattr *nla,
+						  unsigned long defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_msecs(nla);
+}
+
 /**
  * nla_get_in_addr - return payload of IPv4 address attribute
  * @nla: IPv4 address netlink attribute
@@ -1877,6 +2124,21 @@ static inline __be32 nla_get_in_addr(const struct nlattr *nla)
 	return *(__be32 *) nla_data(nla);
 }
 
+/**
+ * nla_get_in_addr_default - return payload of be32 attribute or default
+ * @nla: IPv4 address netlink attribute, may be %NULL
+ * @defvalue: default value to use if @nla is %NULL
+ *
+ * Return: the value of the attribute, or the default value if not present
+ */
+static inline __be32 nla_get_in_addr_default(const struct nlattr *nla,
+					     __be32 defvalue)
+{
+	if (!nla)
+		return defvalue;
+	return nla_get_in_addr(nla);
+}
+
 /**
  * nla_get_in6_addr - return payload of IPv6 address attribute
  * @nla: IPv6 address netlink attribute