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AF_XDP-interaction: Fix bug in mem_frame_allocator

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The assumption was that our simple memory allocator for umem
frames return an addr that point to the start of the frame.

When a frame addr is freed/returned via mem_free_umem_frame()
this frame addr doesn't necessary point to the start of the
frame.  Often this is not the case.  As the kernel RX process
will add some headroom.  Our userspace TX process can also choose
to add headroom, resulting in frames returned in Completion Queue
will also have this headroom offset in the addr.

Fix by removing headroom offset when freeing/returning the
frame addr in mem_free_umem_frame().

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This commit is contained in:
Jesper Dangaard Brouer
2021-12-03 22:30:30 +01:00
parent ea8b2df6aa
commit 37d4f466dd
1 changed files with 22 additions and 7 deletions
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29
AF_XDP-interaction/af_xdp_user.c
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@@ -45,6 +45,7 @@
#define NUM_FRAMES 4096 /* Frames per queue */
#define FRAME_SIZE XSK_UMEM__DEFAULT_FRAME_SIZE /* 4096 */
#define FRAME_SIZE_MASK (FRAME_SIZE - 1)
#define RX_BATCH_SIZE 64
#define INVALID_UMEM_FRAME UINT64_MAX
@@ -290,6 +291,14 @@ static void mem_free_umem_frame(struct mem_frame_allocator *mem, uint64_t frame)
{
assert(mem->umem_frame_free < mem->umem_frame_max);
/* Remove any packet offset from the frame addr. The kernel RX process
* will add some headroom. Our userspace TX process can also choose to
* add headroom. Thus, frame addr can be returned to our mem allocator
* including this offset.
*/
// frame = (frame / FRAME_SIZE) * FRAME_SIZE;
frame = frame & ~FRAME_SIZE_MASK;
mem->umem_frame_addr[mem->umem_frame_free++] = frame;
}
@@ -314,8 +323,10 @@ static void mem_init_umem_frame_allocator(struct mem_frame_allocator *mem,
mem->umem_frame_max = nr_frames;
/* The umem_frame_addr is basically index into umem->buffer memory area */
for (i = 0; i < nr_frames; i++)
mem->umem_frame_addr[i] = i * FRAME_SIZE;
for (i = 0; i < nr_frames; i++) {
uint64_t addr = i * FRAME_SIZE;
mem->umem_frame_addr[i] = addr;
}
mem->umem_frame_free = nr_frames;
}
@@ -463,10 +474,13 @@ static void complete_tx(struct xsk_socket_info *xsk)
&idx_cq);
if (completed > 0) {
for (int i = 0; i < completed; i++)
mem_free_umem_frame(&xsk->umem->mem,
*xsk_ring_cons__comp_addr(&xsk->cq,
idx_cq++));
for (int i = 0; i < completed; i++) {
uint64_t addr;
addr = *xsk_ring_cons__comp_addr(&xsk->cq, idx_cq++);
mem_free_umem_frame(&xsk->umem->mem, addr);
//pr_addr_info(__func__, addr, xsk->umem);
}
xsk_ring_cons__release(&xsk->cq, completed);
xsk->outstanding_tx -= completed < xsk->outstanding_tx ?
@@ -889,6 +903,8 @@ static void handle_receive_packets(struct xsk_socket_info *xsk)
if (!rcvd)
return;
tx_pkt(NULL, xsk);
/* Process received packets */
for (i = 0; i < rcvd; i++) {
uint64_t addr = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx)->addr;
@@ -943,7 +959,6 @@ static void rx_and_process(struct config *cfg,
//printf("XXX i[%d] queue:%d xsk_info:%p \n",
// i, xsk_info->queue_id, xsk_info);
tx_pkt(cfg, xsk_info);
handle_receive_packets(xsk_info);
}
}