Commit ed1182dc authored by Björn Töpel's avatar Björn Töpel Committed by Daniel Borkmann
Browse files

xdp: Handle MEM_TYPE_XSK_BUFF_POOL correctly in xdp_return_buff() 



It turns out that it does exist a path where xdp_return_buff() is
being passed an XDP buffer of type MEM_TYPE_XSK_BUFF_POOL. This path
is when AF_XDP zero-copy mode is enabled, and a buffer is redirected
to a DEVMAP with an attached XDP program that drops the buffer.

This change simply puts the handling of MEM_TYPE_XSK_BUFF_POOL back
into xdp_return_buff().

Fixes: 82c41671 ("xdp: Simplify xdp_return_{frame, frame_rx_napi, buff}")
Reported-by: default avatarMaxim Mikityanskiy <maximmi@nvidia.com>
Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMaxim Mikityanskiy <maximmi@nvidia.com>
Link: https://lore.kernel.org/bpf/20201127171726.123627-1-bjorn.topel@gmail.com
parent 4d521943

net/core/xdp.c

+10 −7
Original line number Diff line number Diff line
@@ -335,11 +335,10 @@ EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model); 
 * scenarios (e.g. queue full), it is possible to return the xdp_frame

 * while still leveraging this protection.  The @napi_direct boolean

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

 * of xdp_frames/pages in those cases. This path is never used by the

 * MEM_TYPE_XSK_BUFF_POOL memory type, so it's explicitly not part of

 * the switch-statement.

 * of xdp_frames/pages in those cases.

 */

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

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

			 struct xdp_buff *xdp)

{

	struct xdp_mem_allocator *xa;

	struct page *page;
@@ -361,6 +360,10 @@ static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct) 
		page = virt_to_page(data); /* Assumes order0 page*/

		put_page(page);

		break;

	case MEM_TYPE_XSK_BUFF_POOL:

		/* NB! Only valid from an xdp_buff! */

		xsk_buff_free(xdp);

		break;

	default:

		/* Not possible, checked in xdp_rxq_info_reg_mem_model() */

		WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
@@ -370,19 +373,19 @@ static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct) 


void xdp_return_frame(struct xdp_frame *xdpf)

{

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

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

}

EXPORT_SYMBOL_GPL(xdp_return_frame);



void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)

{

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

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

}

EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);



void xdp_return_buff(struct xdp_buff *xdp)

{

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

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

}



/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */