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xdp: implement convert_to_xdp_frame for MEM_TYPE_ZERO_COPY 

This commit adds proper MEM_TYPE_ZERO_COPY support for
convert_to_xdp_frame. Converting a MEM_TYPE_ZERO_COPY xdp_buff to an
xdp_frame is done by transforming the MEM_TYPE_ZERO_COPY buffer into a
MEM_TYPE_PAGE_ORDER0 frame. This is costly, and in the future it might
make sense to implement a more sophisticated thread-safe alloc/free
scheme for MEM_TYPE_ZERO_COPY, so that no allocation and copy is
required in the fast-path.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Björn Töpel 2018-08-28 14:44:25 +02:00 committed by Alexei Starovoitov
parent 7d2c6cfc54
commit b0d1beeff2
2 changed files with 42 additions and 2 deletions
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5
include/net/xdp.h
View File

@ -91,6 +91,8 @@ static inline void xdp_scrub_frame(struct xdp_frame *frame)
frame->dev_rx = NULL;
}
struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
/* Convert xdp_buff to xdp_frame */
static inline
struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
@ -99,9 +101,8 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
int metasize;
int headroom;
/* TODO: implement clone, copy, use "native" MEM_TYPE */
if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
return NULL;
return xdp_convert_zc_to_xdp_frame(xdp);
/* Assure headroom is available for storing info */
headroom = xdp->data - xdp->data_hard_start;

39
net/core/xdp.c
View File

@ -398,3 +398,42 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
info->flags = bpf->flags;
}
EXPORT_SYMBOL_GPL(xdp_attachment_setup);
struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
{
unsigned int metasize, headroom, totsize;
void *addr, *data_to_copy;
struct xdp_frame *xdpf;
struct page *page;
/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
metasize = xdp_data_meta_unsupported(xdp) ? 0 :
xdp->data - xdp->data_meta;
headroom = xdp->data - xdp->data_hard_start;
totsize = xdp->data_end - xdp->data + metasize;
if (sizeof(*xdpf) + totsize > PAGE_SIZE)
return NULL;
page = dev_alloc_page();
if (!page)
return NULL;
addr = page_to_virt(page);
xdpf = addr;
memset(xdpf, 0, sizeof(*xdpf));
addr += sizeof(*xdpf);
data_to_copy = metasize ? xdp->data_meta : xdp->data;
memcpy(addr, data_to_copy, totsize);
xdpf->data = addr + metasize;
xdpf->len = totsize - metasize;
xdpf->headroom = 0;
xdpf->metasize = metasize;
xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;
xdp_return_buff(xdp);
return xdpf;
}
EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);