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Commit 389ab7f0 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by Alexei Starovoitov
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xdp: introduce xdp_return_frame_rx_napi 



When sending an xdp_frame through xdp_do_redirect call, then error
cases can happen where the xdp_frame needs to be dropped, and
returning an -errno code isn't sufficient/possible any-longer
(e.g. for cpumap case). This is already fully supported, by simply
calling xdp_return_frame.

This patch is an optimization, which provides xdp_return_frame_rx_napi,
which is a faster variant for these error cases.  It take advantage of
the protection provided by XDP RX running under NAPI protection.

This change is mostly relevant for drivers using the page_pool
allocator as it can take advantage of this. (Tested with mlx5).

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 9940fbf6

include/net/page_pool.h

+3 −2
Original line number Diff line number Diff line
@@ -115,13 +115,14 @@ void page_pool_destroy(struct page_pool *pool); 
void __page_pool_put_page(struct page_pool *pool,

			  struct page *page, bool allow_direct);



static inline void page_pool_put_page(struct page_pool *pool, struct page *page)

static inline void page_pool_put_page(struct page_pool *pool,

				      struct page *page, bool allow_direct)

{

	/* When page_pool isn't compiled-in, net/core/xdp.c doesn't

	 * allow registering MEM_TYPE_PAGE_POOL, but shield linker.

	 */

#ifdef CONFIG_PAGE_POOL

	__page_pool_put_page(pool, page, false);

	__page_pool_put_page(pool, page, allow_direct);

#endif

}

/* Very limited use-cases allow recycle direct */

include/net/xdp.h

+1 −0
Original line number Diff line number Diff line
@@ -104,6 +104,7 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp) 
}



void xdp_return_frame(struct xdp_frame *xdpf);

void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);

void xdp_return_buff(struct xdp_buff *xdp);



int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,

kernel/bpf/cpumap.c

+1 −1
Original line number Diff line number Diff line
@@ -578,7 +578,7 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu, 
		err = __ptr_ring_produce(q, xdpf);

		if (err) {

			drops++;

			xdp_return_frame(xdpf);

			xdp_return_frame_rx_napi(xdpf);

		}

		processed++;

	}

kernel/bpf/devmap.c

+1 −1
Original line number Diff line number Diff line
@@ -239,7 +239,7 @@ static int bq_xmit_all(struct bpf_dtab_netdev *obj, 
		err = dev->netdev_ops->ndo_xdp_xmit(dev, xdpf);

		if (err) {

			drops++;

			xdp_return_frame(xdpf);

			xdp_return_frame_rx_napi(xdpf);

		} else {

			sent++;

		}

net/core/xdp.c

+16 −4
Original line number Diff line number Diff line
@@ -308,7 +308,13 @@ int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq, 
}

EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);



static void xdp_return(void *data, struct xdp_mem_info *mem)

/* XDP RX runs under NAPI protection, and in different delivery error

 * scenarios (e.g. queue full), it is possible to return the xdp_frame

 * while still leveraging this protection.  The @napi_direct boolian

 * is used for those calls sites.  Thus, allowing for faster recycling

 * of xdp_frames/pages in those cases.

 */

static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct)

{

	struct xdp_mem_allocator *xa;

	struct page *page;
@@ -320,7 +326,7 @@ static void xdp_return(void *data, struct xdp_mem_info *mem) 
		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);

		page = virt_to_head_page(data);

		if (xa)

			page_pool_put_page(xa->page_pool, page);

			page_pool_put_page(xa->page_pool, page, napi_direct);

		else

			put_page(page);

		rcu_read_unlock();
@@ -340,12 +346,18 @@ static void xdp_return(void *data, struct xdp_mem_info *mem) 


void xdp_return_frame(struct xdp_frame *xdpf)

{

	xdp_return(xdpf->data, &xdpf->mem);

	__xdp_return(xdpf->data, &xdpf->mem, false);

}

EXPORT_SYMBOL_GPL(xdp_return_frame);



void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)

{

	__xdp_return(xdpf->data, &xdpf->mem, true);

}

EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);



void xdp_return_buff(struct xdp_buff *xdp)

{

	xdp_return(xdp->data, &xdp->rxq->mem);

	__xdp_return(xdp->data, &xdp->rxq->mem, true);

}

EXPORT_SYMBOL_GPL(xdp_return_buff);