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skbuff: add stub to help computing crc32c on SCTP packets 

sctp_compute_checksum requires crc32c symbol (provided by libcrc32c), so
it can't be used in net core. Like it has been done previously with other
symbols (e.g. ipv6_dst_lookup), introduce a stub struct skb_checksum_ops
to allow computation of crc32c checksum in net core after sctp.ko (and thus
libcrc32c) has been loaded.

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Davide Caratti 2017-05-18 15:44:37 +02:00 committed by David S. Miller
parent 6f5b24eed0
commit 9617813dba
3 changed files with 34 additions and 0 deletions
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2
include/linux/skbuff.h
View File

@ -3076,6 +3076,8 @@ struct skb_checksum_ops {
__wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len);
};
extern const struct skb_checksum_ops *crc32c_csum_stub __read_mostly;
__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len,
__wsum csum, const struct skb_checksum_ops *ops);
__wsum skb_checksum(const struct sk_buff *skb, int offset, int len,

26
net/core/skbuff.c
View File

@ -2243,6 +2243,32 @@ __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset,
}
EXPORT_SYMBOL(skb_copy_and_csum_bits);
static __wsum warn_crc32c_csum_update(const void *buff, int len, __wsum sum)
{
net_warn_ratelimited(
"%s: attempt to compute crc32c without libcrc32c.ko\n",
__func__);
return 0;
}
static __wsum warn_crc32c_csum_combine(__wsum csum, __wsum csum2,
int offset, int len)
{
net_warn_ratelimited(
"%s: attempt to compute crc32c without libcrc32c.ko\n",
__func__);
return 0;
}
static const struct skb_checksum_ops default_crc32c_ops = {
.update = warn_crc32c_csum_update,
.combine = warn_crc32c_csum_combine,
};
const struct skb_checksum_ops *crc32c_csum_stub __read_mostly =
&default_crc32c_ops;
EXPORT_SYMBOL(crc32c_csum_stub);
/**
* skb_zerocopy_headlen - Calculate headroom needed for skb_zerocopy()
* @from: source buffer

6
net/sctp/offload.c
View File

@ -98,6 +98,11 @@ static const struct net_offload sctp6_offload = {
},
};
static const struct skb_checksum_ops crc32c_csum_ops = {
.update = sctp_csum_update,
.combine = sctp_csum_combine,
};
int __init sctp_offload_init(void)
{
int ret;
@ -110,6 +115,7 @@ int __init sctp_offload_init(void)
if (ret)
goto ipv4;
crc32c_csum_stub = &crc32c_csum_ops;
return ret;
ipv4: