Re: [PATCH net-next v4 5/6] selftests: net: add multithread server support to iou-zcrx

[Paolo Abeni <pabeni@redhat.com>]

On 7/30/26 12:18 AM, Juanlu Herrero wrote:
> Run the iou-zcrx server as N worker threads, each owning one receive
> queue with its own io_uring and zero-copy receive (zcrx) ifq, so the
> test can exercise multi-queue zero-copy receive.
> 
> The main thread owns the listening socket, accepts connections, and
> dispatches each to the worker owning the queue it landed on by matching
> SO_INCOMING_NAPI_ID against per-queue NAPI IDs.
> 
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Juanlu Herrero <juanlu@fastmail.com>
> ---
>  .../testing/selftests/drivers/net/hw/Makefile |   5 +-
>  .../selftests/drivers/net/hw/iou-zcrx.c       | 290 ++++++++++++++----
>  2 files changed, 226 insertions(+), 69 deletions(-)
> 
> diff --git a/tools/testing/selftests/drivers/net/hw/Makefile b/tools/testing/selftests/drivers/net/hw/Makefile
> index 3cab3b4adbb2e..035581b58bc66 100644
> --- a/tools/testing/selftests/drivers/net/hw/Makefile
> +++ b/tools/testing/selftests/drivers/net/hw/Makefile
> @@ -13,10 +13,6 @@ else
>  $(warning excluding iouring tests, liburing not installed or too old)
>  endif
>  
> -TEST_GEN_FILES := \
> -	$(COND_GEN_FILES) \
> -# end of TEST_GEN_FILES
> -
>  TEST_PROGS = \
>  	csum.py \
>  	devlink_port_split.py \
> @@ -71,6 +67,7 @@ TEST_INCLUDES := \
>  YNL_GEN_FILES := \
>  	ncdevmem \
>  	toeplitz \
> +	$(COND_GEN_FILES) \
>  # end of YNL_GEN_FILES
>  TEST_GEN_FILES += $(YNL_GEN_FILES)
>  TEST_GEN_FILES += $(patsubst %.c,%.o,$(wildcard *.bpf.c))
> diff --git a/tools/testing/selftests/drivers/net/hw/iou-zcrx.c b/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
> index 7bc61f3b70ca6..16259129df46d 100644
> --- a/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
> +++ b/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
> @@ -27,6 +27,7 @@
>  #include <netinet/tcp.h>
>  #include <netinet/udp.h>
>  #include <sys/epoll.h>
> +#include <sys/eventfd.h>
>  #include <sys/ioctl.h>
>  #include <sys/mman.h>
>  #include <sys/resource.h>
> @@ -38,6 +39,8 @@
>  #include <sys/wait.h>
>  
>  #include <liburing.h>
> +#include <ynl.h>
> +#include "netdev-user.h"
>  
>  #define SKIP_CODE	42
>  
> @@ -91,6 +94,7 @@ static int cfg_num_threads = 1;
>  static char *payload;
>  
>  #define CONNS_PER_THREAD	4
> +#define MAX_CONNS_PER_THREAD	64
>  
>  struct thread_ctx {
>  	struct io_uring		ring;
> @@ -99,9 +103,14 @@ struct thread_ctx {
>  	size_t			ring_size;
>  	struct io_uring_zcrx_rq	rq_ring;
>  	unsigned long		area_token;
> -	int			connfd;
> -	bool			stop;
> -	size_t			received;
> +	int			queue_id;
> +	int			napi_id;
> +	int			ready_fd;
> +	int			start_fd;
> +
> +	int			connfds[MAX_CONNS_PER_THREAD];
> +	size_t			received[MAX_CONNS_PER_THREAD];
> +	int			nr_conns;
>  };
>  
>  static unsigned long gettimeofday_ms(void)
> @@ -201,7 +210,7 @@ static void setup_zcrx(struct thread_ctx *ctx)
>  
>  	struct t_io_uring_zcrx_ifq_reg reg = {
>  		.if_idx = ifindex,
> -		.if_rxq = cfg_queue_id,
> +		.if_rxq = ctx->queue_id,
>  		.rq_entries = rq_entries,
>  		.area_ptr = (__u64)(unsigned long)&area_reg,
>  		.region_ptr = (__u64)(unsigned long)&region_reg,
> @@ -226,53 +235,32 @@ static void setup_zcrx(struct thread_ctx *ctx)
>  	ctx->area_token = area_reg.rq_area_token;
>  }
>  
> -static void add_accept(struct thread_ctx *ctx, int sockfd)
> +static void add_recvzc(struct thread_ctx *ctx, int conn_idx)
>  {
>  	struct io_uring_sqe *sqe;
>  
>  	sqe = io_uring_get_sqe(&ctx->ring);
>  
> -	io_uring_prep_accept(sqe, sockfd, NULL, NULL, 0);
> -	sqe->user_data = 1;
> -}
> -
> -static void add_recvzc(struct thread_ctx *ctx, int sockfd)
> -{
> -	struct io_uring_sqe *sqe;
> -
> -	sqe = io_uring_get_sqe(&ctx->ring);
> -
> -	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, sockfd, NULL, 0, 0);
> +	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, ctx->connfds[conn_idx],
> +			 NULL, 0, 0);
>  	sqe->ioprio |= IORING_RECV_MULTISHOT;
> -	sqe->user_data = 2;
> +	sqe->user_data = conn_idx;
>  }
>  
> -static void add_recvzc_oneshot(struct thread_ctx *ctx, int sockfd, size_t len)
> +static void add_recvzc_oneshot(struct thread_ctx *ctx, int conn_idx, size_t len)
>  {
>  	struct io_uring_sqe *sqe;
>  
>  	sqe = io_uring_get_sqe(&ctx->ring);
>  
> -	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, sockfd, NULL, len, 0);
> +	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, ctx->connfds[conn_idx],
> +			 NULL, len, 0);
>  	sqe->ioprio |= IORING_RECV_MULTISHOT;
> -	sqe->user_data = 2;
> +	sqe->user_data = conn_idx;
>  }
>  
> -static void process_accept(struct thread_ctx *ctx, struct io_uring_cqe *cqe)
> -{
> -	if (cqe->res < 0)
> -		error(1, 0, "accept()");
> -	if (ctx->connfd)
> -		error(1, 0, "Unexpected second connection");
> -
> -	ctx->connfd = cqe->res;
> -	if (cfg_oneshot)
> -		add_recvzc_oneshot(ctx, ctx->connfd, page_size);
> -	else
> -		add_recvzc(ctx, ctx->connfd);
> -}
> -
> -static void process_recvzc(struct thread_ctx *ctx, struct io_uring_cqe *cqe)
> +static void process_recvzc(struct thread_ctx *ctx, struct io_uring_cqe *cqe,
> +			   int conn_idx)
>  {
>  	unsigned int rq_mask = ctx->rq_ring.ring_entries - 1;
>  	struct io_uring_zcrx_cqe *rcqe;
> @@ -283,7 +271,7 @@ static void process_recvzc(struct thread_ctx *ctx, struct io_uring_cqe *cqe)
>  	int i;
>  
>  	if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs == 0) {
> -		ctx->stop = true;
> +		ctx->nr_conns--;
>  		return;
>  	}
>  
> @@ -292,11 +280,11 @@ static void process_recvzc(struct thread_ctx *ctx, struct io_uring_cqe *cqe)
>  
>  	if (cfg_oneshot) {
>  		if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs) {
> -			add_recvzc_oneshot(ctx, ctx->connfd, page_size);
> +			add_recvzc_oneshot(ctx, conn_idx, page_size);
>  			cfg_oneshot_recvs--;

Sashiko noted that the above update is now racy in multithread tests:

https://sashiko.dev/#/patchset/20260729221825.42773-1-juanlu%40fastmail.com

Also please respect the reverse christmas tree order consistently.

/P