[PATCH v2 01/10] net: introduce CONFIG_NET_CRC32C

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

Add a hidden kconfig symbol NET_CRC32C that will group together the
functions that calculate CRC32C checksums of packets, so that these
don't have to be built into NET-enabled kernels that don't need them.

Make skb_crc32c_csum_help() (which is called only when IP_SCTP is
enabled) conditional on this symbol, and make IP_SCTP select it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 net/Kconfig      | 4 ++++
 net/core/dev.c   | 2 ++
 net/sctp/Kconfig | 1 +
 3 files changed, 7 insertions(+)

diff --git a/net/Kconfig b/net/Kconfig
index 202cc595e5e6f..5b71a52987d33 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -73,10 +73,14 @@ config NET_DEVMEM
 	depends on PAGE_POOL
 
 config NET_SHAPER
 	bool
 
+config NET_CRC32C
+	bool
+	select CRC32
+
 menu "Networking options"
 
 source "net/packet/Kconfig"
 source "net/unix/Kconfig"
 source "net/tls/Kconfig"
diff --git a/net/core/dev.c b/net/core/dev.c
index fccf2167b2352..d93bee5eb5d8c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3594,10 +3594,11 @@ int skb_checksum_help(struct sk_buff *skb)
 out:
 	return ret;
 }
 EXPORT_SYMBOL(skb_checksum_help);
 
+#ifdef CONFIG_NET_CRC32C
 int skb_crc32c_csum_help(struct sk_buff *skb)
 {
 	__le32 crc32c_csum;
 	int ret = 0, offset, start;
 
@@ -3633,10 +3634,11 @@ int skb_crc32c_csum_help(struct sk_buff *skb)
 	skb_reset_csum_not_inet(skb);
 out:
 	return ret;
 }
 EXPORT_SYMBOL(skb_crc32c_csum_help);
+#endif /* CONFIG_NET_CRC32C */
 
 __be16 skb_network_protocol(struct sk_buff *skb, int *depth)
 {
 	__be16 type = skb->protocol;
 
diff --git a/net/sctp/Kconfig b/net/sctp/Kconfig
index d18a72df3654e..3669ba3518563 100644
--- a/net/sctp/Kconfig
+++ b/net/sctp/Kconfig
@@ -9,10 +9,11 @@ menuconfig IP_SCTP
 	depends on IPV6 || IPV6=n
 	select CRC32
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_SHA1
+	select NET_CRC32C
 	select NET_UDP_TUNNEL
 	help
 	  Stream Control Transmission Protocol
 
 	  From RFC 2960 <http://www.ietf.org/rfc/rfc2960.txt>.

base-commit: a8ae8a0e848e3506c95e45e7cb6e640502495f1a
-- 
2.49.0