Commit d65a1906 authored by Lorenzo Bianconi's avatar Lorenzo Bianconi Committed by Alexei Starovoitov
Browse files

net: xdp: add xdp_update_skb_shared_info utility routine 



Introduce xdp_update_skb_shared_info routine to update frags array
metadata in skb_shared_info data structure converting to a skb from
a xdp_buff or xdp_frame.
According to the current skb_shared_info architecture in
xdp_frame/xdp_buff and to the xdp frags support, there is
no need to run skb_add_rx_frag() and reset frags array converting the buffer
to a skb since the frag array will be in the same position for xdp_buff/xdp_frame
and for the skb, we just need to update memory metadata.
Introduce XDP_FLAGS_PF_MEMALLOC flag in xdp_buff_flags in order to mark
the xdp_buff or xdp_frame as under memory-pressure if pages of the frags array
are under memory pressure. Doing so we can avoid looping over all fragments in
xdp_update_skb_shared_info routine. The driver is expected to set the
flag constructing the xdp_buffer using xdp_buff_set_frag_pfmemalloc
utility routine.
Rely on xdp_update_skb_shared_info in __xdp_build_skb_from_frame routine
converting the non-linear xdp_frame to a skb after performing a XDP_REDIRECT.

Acked-by: default avatarToke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Acked-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarLorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/bfd23fb8a8d7438724f7819c567cdf99ffd6226f.1642758637.git.lorenzo@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent d094c985

include/net/xdp.h

+32 −1
Original line number Diff line number Diff line
@@ -68,6 +68,9 @@ struct xdp_txq_info { 


enum xdp_buff_flags {

	XDP_FLAGS_HAS_FRAGS		= BIT(0), /* non-linear xdp buff */

	XDP_FLAGS_FRAGS_PF_MEMALLOC	= BIT(1), /* xdp paged memory is under

						   * pressure

						   */

};



struct xdp_buff {
@@ -96,6 +99,16 @@ static __always_inline void xdp_buff_clear_frags_flag(struct xdp_buff *xdp) 
	xdp->flags &= ~XDP_FLAGS_HAS_FRAGS;

}



static __always_inline bool xdp_buff_is_frag_pfmemalloc(struct xdp_buff *xdp)

{

	return !!(xdp->flags & XDP_FLAGS_FRAGS_PF_MEMALLOC);

}



static __always_inline void xdp_buff_set_frag_pfmemalloc(struct xdp_buff *xdp)

{

	xdp->flags |= XDP_FLAGS_FRAGS_PF_MEMALLOC;

}



static __always_inline void

xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info *rxq)

{
@@ -151,6 +164,11 @@ static __always_inline bool xdp_frame_has_frags(struct xdp_frame *frame) 
	return !!(frame->flags & XDP_FLAGS_HAS_FRAGS);

}



static __always_inline bool xdp_frame_is_frag_pfmemalloc(struct xdp_frame *frame)

{

	return !!(frame->flags & XDP_FLAGS_FRAGS_PF_MEMALLOC);

}



#define XDP_BULK_QUEUE_SIZE	16

struct xdp_frame_bulk {

	int count;
@@ -186,6 +204,19 @@ static inline void xdp_scrub_frame(struct xdp_frame *frame) 
	frame->dev_rx = NULL;

}



static inline void

xdp_update_skb_shared_info(struct sk_buff *skb, u8 nr_frags,

			   unsigned int size, unsigned int truesize,

			   bool pfmemalloc)

{

	skb_shinfo(skb)->nr_frags = nr_frags;



	skb->len += size;

	skb->data_len += size;

	skb->truesize += truesize;

	skb->pfmemalloc |= pfmemalloc;

}



/* Avoids inlining WARN macro in fast-path */

void xdp_warn(const char *msg, const char *func, const int line);

#define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)

net/core/xdp.c

+12 −0
Original line number Diff line number Diff line
@@ -561,8 +561,14 @@ struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf, 
					   struct sk_buff *skb,

					   struct net_device *dev)

{

	struct skb_shared_info *sinfo = xdp_get_shared_info_from_frame(xdpf);

	unsigned int headroom, frame_size;

	void *hard_start;

	u8 nr_frags;



	/* xdp frags frame */

	if (unlikely(xdp_frame_has_frags(xdpf)))

		nr_frags = sinfo->nr_frags;



	/* Part of headroom was reserved to xdpf */

	headroom = sizeof(*xdpf) + xdpf->headroom;
@@ -582,6 +588,12 @@ struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf, 
	if (xdpf->metasize)

		skb_metadata_set(skb, xdpf->metasize);



	if (unlikely(xdp_frame_has_frags(xdpf)))

		xdp_update_skb_shared_info(skb, nr_frags,

					   sinfo->xdp_frags_size,

					   nr_frags * xdpf->frame_sz,

					   xdp_frame_is_frag_pfmemalloc(xdpf));



	/* Essential SKB info: protocol and skb->dev */

	skb->protocol = eth_type_trans(skb, dev);