Re: [PATCH net-next v5 3/6] selftests: net: refactor server state into struct thread_ctx

[David Wei <dw@davidwei.uk>]

On 2026-08-13 18:23, Juanlu Herrero wrote:
> Move server-side state (io_uring ring, zcrx area, refill ring, receive
> tracking) from global variables into a local struct thread_ctx. This is
> a pure refactor with no behavior change: run_server still allocates a
> single context on the stack and runs single-threaded, using io_uring
> accept and recvzc as before.
> 
> This prepares the ground for the multithread server support in the
> following commits, which spawns N worker threads each with their own
> struct thread_ctx.
> 
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Juanlu Herrero <juanlu@fastmail.com>
> ---
>   .../selftests/drivers/net/hw/iou-zcrx.c       | 156 +++++++++---------
>   1 file changed, 80 insertions(+), 76 deletions(-)
> 
> diff --git a/tools/testing/selftests/drivers/net/hw/iou-zcrx.c b/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
> index c6dbd0ad53681..9b62fd0703e61 100644
> --- a/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
> +++ b/tools/testing/selftests/drivers/net/hw/iou-zcrx.c
> @@ -87,14 +87,18 @@ static unsigned int cfg_rx_buf_len;
>   static bool cfg_dry_run;
>   
>   static char *payload;
> -static void *area_ptr;
> -static void *ring_ptr;
> -static size_t ring_size;
> -static struct io_uring_zcrx_rq rq_ring;
> -static unsigned long area_token;
> -static int connfd;
> -static bool stop;
> -static size_t received;
> +
> +struct thread_ctx {
> +	struct io_uring		ring;
> +	void			*area_ptr;
> +	void			*ring_ptr;
> +	size_t			ring_size;
> +	struct io_uring_zcrx_rq	rq_ring;
> +	unsigned long		area_token;
> +	int			connfd;
> +	bool			stop;
> +	size_t			received;
> +};
>   
>   static unsigned long gettimeofday_ms(void)
>   {
> @@ -138,7 +142,7 @@ static inline size_t get_refill_ring_size(unsigned int rq_entries)
>   	return ALIGN_UP(size, page_size);
>   }
>   
> -static void setup_zcrx(struct io_uring *ring)
> +static void setup_zcrx(struct thread_ctx *ctx)
>   {
>   	unsigned int ifindex;
>   	unsigned int rq_entries = 4096;
> @@ -149,44 +153,44 @@ static void setup_zcrx(struct io_uring *ring)
>   		error(1, 0, "bad interface name: %s", cfg_ifname);
>   
>   	if (cfg_rx_buf_len && cfg_rx_buf_len != page_size) {
> -		area_ptr = mmap(NULL,
> -				AREA_SIZE,
> -				PROT_READ | PROT_WRITE,
> -				MAP_ANONYMOUS | MAP_PRIVATE |
> -				MAP_HUGETLB | MAP_HUGE_2MB,
> -				-1,
> -				0);
> -		if (area_ptr == MAP_FAILED) {
> +		ctx->area_ptr = mmap(NULL,
> +				     AREA_SIZE,
> +				     PROT_READ | PROT_WRITE,
> +				     MAP_ANONYMOUS | MAP_PRIVATE |
> +				     MAP_HUGETLB | MAP_HUGE_2MB,
> +				     -1,
> +				     0);
> +		if (ctx->area_ptr == MAP_FAILED) {
>   			printf("Can't allocate huge pages\n");
>   			exit(SKIP_CODE);
>   		}
>   	} else {
> -		area_ptr = mmap(NULL,
> -				AREA_SIZE,
> -				PROT_READ | PROT_WRITE,
> -				MAP_ANONYMOUS | MAP_PRIVATE,
> -				0,
> -				0);
> -		if (area_ptr == MAP_FAILED)
> +		ctx->area_ptr = mmap(NULL,
> +				     AREA_SIZE,
> +				     PROT_READ | PROT_WRITE,
> +				     MAP_ANONYMOUS | MAP_PRIVATE,
> +				     0,
> +				     0);
> +		if (ctx->area_ptr == MAP_FAILED)
>   			error(1, 0, "mmap(): zero copy area");
>   	}
>   
> -	ring_size = get_refill_ring_size(rq_entries);
> -	ring_ptr = mmap(NULL,
> -			ring_size,
> -			PROT_READ | PROT_WRITE,
> -			MAP_ANONYMOUS | MAP_PRIVATE,
> -			0,
> -			0);
> +	ctx->ring_size = get_refill_ring_size(rq_entries);
> +	ctx->ring_ptr = mmap(NULL,
> +			     ctx->ring_size,
> +			     PROT_READ | PROT_WRITE,
> +			     MAP_ANONYMOUS | MAP_PRIVATE,
> +			     0,
> +			     0);
>   
>   	struct io_uring_region_desc region_reg = {
> -		.size = ring_size,
> -		.user_addr = (__u64)(unsigned long)ring_ptr,
> +		.size = ctx->ring_size,
> +		.user_addr = (__u64)(unsigned long)ctx->ring_ptr,
>   		.flags = IORING_MEM_REGION_TYPE_USER,
>   	};
>   
>   	struct io_uring_zcrx_area_reg area_reg = {
> -		.addr = (__u64)(unsigned long)area_ptr,
> +		.addr = (__u64)(unsigned long)ctx->area_ptr,
>   		.len = AREA_SIZE,
>   		.flags = 0,
>   	};
> @@ -200,7 +204,7 @@ static void setup_zcrx(struct io_uring *ring)
>   		.rx_buf_len = cfg_rx_buf_len,
>   	};
>   
> -	ret = io_uring_register_ifq(ring, (void *)&reg);
> +	ret = io_uring_register_ifq(&ctx->ring, (void *)&reg);
>   	if (cfg_rx_buf_len && (ret == -EINVAL || ret == -EOPNOTSUPP ||
>   			       ret == -ERANGE)) {
>   		printf("Large chunks are not supported %i\n", ret);
> @@ -209,64 +213,64 @@ static void setup_zcrx(struct io_uring *ring)
>   		error(1, 0, "io_uring_register_ifq(): %d", ret);
>   	}
>   
> -	rq_ring.khead = (unsigned int *)((char *)ring_ptr + reg.offsets.head);
> -	rq_ring.ktail = (unsigned int *)((char *)ring_ptr + reg.offsets.tail);
> -	rq_ring.rqes = (struct io_uring_zcrx_rqe *)((char *)ring_ptr + reg.offsets.rqes);
> -	rq_ring.rq_tail = 0;
> -	rq_ring.ring_entries = reg.rq_entries;
> +	ctx->rq_ring.khead = (unsigned int *)((char *)ctx->ring_ptr + reg.offsets.head);
> +	ctx->rq_ring.ktail = (unsigned int *)((char *)ctx->ring_ptr + reg.offsets.tail);
> +	ctx->rq_ring.rqes = (struct io_uring_zcrx_rqe *)((char *)ctx->ring_ptr + reg.offsets.rqes);
> +	ctx->rq_ring.rq_tail = 0;
> +	ctx->rq_ring.ring_entries = reg.rq_entries;
>   
> -	area_token = area_reg.rq_area_token;
> +	ctx->area_token = area_reg.rq_area_token;
>   }
>   
> -static void add_accept(struct io_uring *ring, int sockfd)
> +static void add_accept(struct thread_ctx *ctx, int sockfd)
>   {
>   	struct io_uring_sqe *sqe;
>   
> -	sqe = io_uring_get_sqe(ring);
> +	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 io_uring *ring, int sockfd)
> +static void add_recvzc(struct thread_ctx *ctx, int sockfd)
>   {
>   	struct io_uring_sqe *sqe;
>   
> -	sqe = io_uring_get_sqe(ring);
> +	sqe = io_uring_get_sqe(&ctx->ring);
>   
>   	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, sockfd, NULL, 0, 0);
>   	sqe->ioprio |= IORING_RECV_MULTISHOT;
>   	sqe->user_data = 2;
>   }
>   
> -static void add_recvzc_oneshot(struct io_uring *ring, int sockfd, size_t len)
> +static void add_recvzc_oneshot(struct thread_ctx *ctx, int sockfd, size_t len)
>   {
>   	struct io_uring_sqe *sqe;
>   
> -	sqe = io_uring_get_sqe(ring);
> +	sqe = io_uring_get_sqe(&ctx->ring);
>   
>   	io_uring_prep_rw(IORING_OP_RECV_ZC, sqe, sockfd, NULL, len, 0);
>   	sqe->ioprio |= IORING_RECV_MULTISHOT;
>   	sqe->user_data = 2;
>   }
>   
> -static void process_accept(struct io_uring *ring, struct io_uring_cqe *cqe)
> +static void process_accept(struct thread_ctx *ctx, struct io_uring_cqe *cqe)
>   {
>   	if (cqe->res < 0)
>   		error(1, 0, "accept()");
> -	if (connfd)
> +	if (ctx->connfd)
>   		error(1, 0, "Unexpected second connection");
>   
> -	connfd = cqe->res;
> +	ctx->connfd = cqe->res;
>   	if (cfg_oneshot)
> -		add_recvzc_oneshot(ring, connfd, page_size);
> +		add_recvzc_oneshot(ctx, ctx->connfd, page_size);
>   	else
> -		add_recvzc(ring, connfd);
> +		add_recvzc(ctx, ctx->connfd);
>   }
>   
> -static void process_recvzc(struct io_uring *ring, struct io_uring_cqe *cqe)
> +static void process_recvzc(struct thread_ctx *ctx, struct io_uring_cqe *cqe)
>   {
> -	unsigned rq_mask = rq_ring.ring_entries - 1;
> +	unsigned int rq_mask = ctx->rq_ring.ring_entries - 1;
>   	struct io_uring_zcrx_cqe *rcqe;
>   	struct io_uring_zcrx_rqe *rqe;
>   	uint64_t mask;
> @@ -275,7 +279,7 @@ static void process_recvzc(struct io_uring *ring, struct io_uring_cqe *cqe)
>   	int i;
>   
>   	if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs == 0) {
> -		stop = true;
> +		ctx->stop = true;
>   		return;
>   	}
>   
> @@ -284,56 +288,56 @@ static void process_recvzc(struct io_uring *ring, struct io_uring_cqe *cqe)
>   
>   	if (cfg_oneshot) {
>   		if (cqe->res == 0 && cqe->flags == 0 && cfg_oneshot_recvs) {
> -			add_recvzc_oneshot(ring, connfd, page_size);
> +			add_recvzc_oneshot(ctx, ctx->connfd, page_size);
>   			cfg_oneshot_recvs--;
>   		}
>   	} else if (!(cqe->flags & IORING_CQE_F_MORE)) {
> -		add_recvzc(ring, connfd);
> +		add_recvzc(ctx, ctx->connfd);
>   	}
>   
>   	rcqe = (struct io_uring_zcrx_cqe *)(cqe + 1);
>   
>   	n = cqe->res;
>   	mask = (1ULL << IORING_ZCRX_AREA_SHIFT) - 1;
> -	data = (char *)area_ptr + (rcqe->off & mask);
> +	data = (char *)ctx->area_ptr + (rcqe->off & mask);
>   
>   	for (i = 0; i < n; i++) {
> -		if (*(data + i) != payload[(received + i)])
> +		if (*(data + i) != payload[(ctx->received + i)])
>   			error(1, 0, "payload mismatch at %d", i);
>   	}
> -	received += n;
> +	ctx->received += n;
>   
> -	rqe = &rq_ring.rqes[(rq_ring.rq_tail & rq_mask)];
> -	rqe->off = (rcqe->off & ~IORING_ZCRX_AREA_MASK) | area_token;
> +	rqe = &ctx->rq_ring.rqes[(ctx->rq_ring.rq_tail & rq_mask)];
> +	rqe->off = (rcqe->off & ~IORING_ZCRX_AREA_MASK) | ctx->area_token;
>   	rqe->len = cqe->res;
> -	io_uring_smp_store_release(rq_ring.ktail, ++rq_ring.rq_tail);
> +	io_uring_smp_store_release(ctx->rq_ring.ktail, ++ctx->rq_ring.rq_tail);
>   }
>   
> -static void server_loop(struct io_uring *ring)
> +static void server_loop(struct thread_ctx *ctx)
>   {
>   	struct io_uring_cqe *cqe;
>   	unsigned int count = 0;
>   	unsigned int head;
>   	int i, ret;
>   
> -	io_uring_submit_and_wait(ring, 1);
> +	io_uring_submit_and_wait(&ctx->ring, 1);
>   
> -	io_uring_for_each_cqe(ring, head, cqe) {
> +	io_uring_for_each_cqe(&ctx->ring, head, cqe) {
>   		if (cqe->user_data == 1)
> -			process_accept(ring, cqe);
> +			process_accept(ctx, cqe);
>   		else if (cqe->user_data == 2)
> -			process_recvzc(ring, cqe);
> +			process_recvzc(ctx, cqe);
>   		else
>   			error(1, 0, "unknown cqe");
>   		count++;
>   	}
> -	io_uring_cq_advance(ring, count);
> +	io_uring_cq_advance(&ctx->ring, count);
>   }
>   
>   static void run_server(void)
>   {
> +	struct thread_ctx ctx = {};
>   	unsigned int flags = 0;
> -	struct io_uring ring;
>   	int fd, enable, ret;
>   	uint64_t tstop;
>   
> @@ -356,22 +360,22 @@ static void run_server(void)
>   	flags |= IORING_SETUP_SUBMIT_ALL;
>   	flags |= IORING_SETUP_CQE32;
>   
> -	io_uring_queue_init(512, &ring, flags);
> +	io_uring_queue_init(512, &ctx.ring, flags);
>   
> -	setup_zcrx(&ring);
> +	setup_zcrx(&ctx);
>   	if (cfg_dry_run)
>   		return;
>   
>   	if (listen(fd, 1024) < 0)
>   		error(1, 0, "listen()");
>   
> -	add_accept(&ring, fd);
> +	add_accept(&ctx, fd);
>   
>   	tstop = gettimeofday_ms() + 5000;
> -	while (!stop && gettimeofday_ms() < tstop)
> -		server_loop(&ring);
> +	while (!ctx.stop && gettimeofday_ms() < tstop)
> +		server_loop(&ctx);
>   
> -	if (!stop)
> +	if (!ctx.stop)
>   		error(1, 0, "test failed\n");
>   }
>   

Reviewed-by: David Wei <dw@davidwei.uk>