Re: [RFC bpf-next 1/2] bpf: cpumap: add the possibility to attach a eBPF program to cpumap

On Fri, 22 May 2020 11:44:04 -0600
David Ahern [off-list ref] wrote:

On 5/22/20 10:11 AM, Lorenzo Bianconi wrote:

quoted

@@ -259,28 +270,64 @@ static int cpu_map_kthread_run(void *data)
 		 * kthread CPU pinned. Lockless access to ptr_ring
 		 * consume side valid as no-resize allowed of queue.
 		 */
-		n = ptr_ring_consume_batched(rcpu->queue, frames, CPUMAP_BATCH);
+		n = ptr_ring_consume_batched(rcpu->queue, xdp_frames,
+					     CPUMAP_BATCH);
 
+		rcu_read_lock();
+
+		prog = READ_ONCE(rcpu->prog);
 		for (i = 0; i < n; i++) {
-			void *f = frames[i];
+			void *f = xdp_frames[i];
 			struct page *page = virt_to_page(f);
+			struct xdp_frame *xdpf;
+			struct xdp_buff xdp;
+			u32 act;
 
 			/* Bring struct page memory area to curr CPU. Read by
 			 * build_skb_around via page_is_pfmemalloc(), and when
 			 * freed written by page_frag_free call.
 			 */
 			prefetchw(page);
+			if (!prog) {
+				frames[nframes++] = xdp_frames[i];
+				continue;
+			}
+
+			xdpf = f;
+			xdp.data_hard_start = xdpf->data - xdpf->headroom;
+			xdp.data = xdpf->data;
+			xdp.data_end = xdpf->data + xdpf->len;
+			xdp.data_meta = xdpf->data - xdpf->metasize;
+			xdp.frame_sz = xdpf->frame_sz;
+			/* TODO: rxq */
+
+			act = bpf_prog_run_xdp(prog, &xdp);  

Why not run the program in cpu_map_enqueue before converting from
xdp_buff to xdp_frame?

Because we want to run the XDP-prog on the remote-CPU.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer