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net: skb_copy_datagram_const_iovec()

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There's an skb_copy_datagram_iovec() to copy out of a paged skb,
but it modifies the iovec, and does not support starting
at an offset in the destination. We want both in tun.c, so let's
add the function.

It's a carbon copy of skb_copy_datagram_iovec() with enough changes to
be annoying.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin
2009-04-20 01:25:46 +00:00
committed by David S. Miller
parent 0cededf3ff
commit 0a1ec07a67
4 changed files with 125 additions and 0 deletions
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26
net/core/iovec.c
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@@ -97,6 +97,31 @@ int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
return 0;
}
/*
* Copy kernel to iovec. Returns -EFAULT on error.
*/
int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
int offset, int len)
{
int copy;
for (; len > 0; ++iov) {
/* Skip over the finished iovecs */
if (unlikely(offset >= iov->iov_len)) {
offset -= iov->iov_len;
continue;
}
copy = min_t(unsigned int, iov->iov_len - offset, len);
offset = 0;
if (copy_to_user(iov->iov_base, kdata, copy))
return -EFAULT;
kdata += copy;
len -= copy;
}
return 0;
}
/*
* Copy iovec to kernel. Returns -EFAULT on error.
*
@@ -236,3 +261,4 @@ EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
EXPORT_SYMBOL(memcpy_fromiovec);
EXPORT_SYMBOL(memcpy_fromiovecend);
EXPORT_SYMBOL(memcpy_toiovec);
EXPORT_SYMBOL(memcpy_toiovecend);