On 2021/8/10 11:40, Zhu Yanjun wrote:
> On Mon, Aug 9, 2021 at 10:43 PM Xiao Yang <yangx.jy@xxxxxxxxxxx> wrote:
>> Resid indicates the residual length of transmitted bytes but current
>> rxe sets it to zero for inline data at the beginning. In this case,
>> request will transmit zero byte to responder wrongly.
> What are the symptoms if resid is set to zero?
Hi Yanjun,
You can construct code by the attached patch and then run
rdma_client/server to reproduce the issue.
If resid is set to zero, running rdma_client/server:
--------------------------------
# ./rdma_client -s 10.167.220.99 -p 8765
rdma_client: start
rdma_client: end 0
# ./rdma_server -s 10.167.220.99 -p 8765
rdma_server: start
wc.byte_len 0 recv_msg bbbbbbbbbbbbbbbb
rdma_server: end 0
--------------------------------
rdma_client sends zero byte instead of 16 btyes to rdma_server.
rdma_server receives zero byte instead of 16 btyes from rdma_client.
Please also see the logic about resid in kernel, for example:
--------------------------------
int rxe_requester(void *arg)
{
...
payload = (mask & RXE_WRITE_OR_SEND) ? wqe->dma.resid : 0;
...
skb = init_req_packet(qp, wqe, opcode, payload, &pkt);
...
}
--------------------------------
Best Regards,
Xiao Yang
> Thanks
> Zhu Yanjun
>
>> Resid should be set to the total length of transmitted bytes at the
>> beginning.
>>
>> Note:
>> Just remove the useless setting of resid in init_send_wqe().
>>
>> Fixes: 1a894ca10105 ("Providers/rxe: Implement ibv_create_qp_ex verb")
>> Fixes: 8337db5df125 ("Providers/rxe: Implement memory windows")
>> Signed-off-by: Xiao Yang <yangx.jy@xxxxxxxxxxx>
>> ---
>> providers/rxe/rxe.c | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/providers/rxe/rxe.c b/providers/rxe/rxe.c
>> index 3c3ea8bb..3533a325 100644
>> --- a/providers/rxe/rxe.c
>> +++ b/providers/rxe/rxe.c
>> @@ -1004,7 +1004,7 @@ static void wr_set_inline_data(struct ibv_qp_ex *ibqp, void *addr,
>>
>> memcpy(wqe->dma.inline_data, addr, length);
>> wqe->dma.length = length;
>> - wqe->dma.resid = 0;
>> + wqe->dma.resid = length;
>> }
>>
>> static void wr_set_inline_data_list(struct ibv_qp_ex *ibqp, size_t num_buf,
>> @@ -1035,6 +1035,7 @@ static void wr_set_inline_data_list(struct ibv_qp_ex *ibqp, size_t num_buf,
>> }
>>
>> wqe->dma.length = tot_length;
>> + wqe->dma.resid = tot_length;
>> }
>>
>> static void wr_set_sge(struct ibv_qp_ex *ibqp, uint32_t lkey, uint64_t addr,
>> @@ -1473,8 +1474,6 @@ static int init_send_wqe(struct rxe_qp *qp, struct rxe_wq *sq,
>> if (ibwr->send_flags & IBV_SEND_INLINE) {
>> uint8_t *inline_data = wqe->dma.inline_data;
>>
>> - wqe->dma.resid = 0;
>> -
>> for (i = 0; i < num_sge; i++) {
>> memcpy(inline_data,
>> (uint8_t *)(long)ibwr->sg_list[i].addr,
>> --
>> 2.25.1
>>
>>
>>
From 5f2ff0e6f5ee3c4431a27e6bfba0868ad59ef56f Mon Sep 17 00:00:00 2001
From: Xiao Yang <yangx.jy@xxxxxxxxxxx>
Date: Wed, 11 Aug 2021 00:46:31 +0800
Subject: [PATCH] rxe: construct code and reproduce the issue by
rdma_client/server
Signed-off-by: Xiao Yang <yangx.jy@xxxxxxxxxxx>
---
librdmacm/examples/rdma_client.c | 2 ++
librdmacm/examples/rdma_server.c | 4 ++++
providers/rxe/rxe.c | 2 +-
3 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/librdmacm/examples/rdma_client.c b/librdmacm/examples/rdma_client.c
index c27047c5..6e568110 100644
--- a/librdmacm/examples/rdma_client.c
+++ b/librdmacm/examples/rdma_client.c
@@ -52,6 +52,8 @@ static int run(void)
struct ibv_wc wc;
int ret;
+ memset(send_msg, 'a', 16);
+
memset(&hints, 0, sizeof hints);
hints.ai_port_space = RDMA_PS_TCP;
ret = rdma_getaddrinfo(server, port, &hints, &res);
diff --git a/librdmacm/examples/rdma_server.c b/librdmacm/examples/rdma_server.c
index f9c766b2..ffb440c6 100644
--- a/librdmacm/examples/rdma_server.c
+++ b/librdmacm/examples/rdma_server.c
@@ -53,6 +53,8 @@ static int run(void)
struct ibv_wc wc;
int ret;
+ memset(recv_msg, 'b', 16);
+
memset(&hints, 0, sizeof hints);
hints.ai_flags = RAI_PASSIVE;
hints.ai_port_space = RDMA_PS_TCP;
@@ -132,6 +134,8 @@ static int run(void)
goto out_disconnect;
}
+ printf("wc.byte_len %u recv_msg %s\n", wc.byte_len, recv_msg);
+
ret = rdma_post_send(id, NULL, send_msg, 16, send_mr, send_flags);
if (ret) {
perror("rdma_post_send");
diff --git a/providers/rxe/rxe.c b/providers/rxe/rxe.c
index 3c3ea8bb..ed5479fe 100644
--- a/providers/rxe/rxe.c
+++ b/providers/rxe/rxe.c
@@ -1492,7 +1492,7 @@ static int init_send_wqe(struct rxe_qp *qp, struct rxe_wq *sq,
wqe->iova = ibwr->wr.rdma.remote_addr;
wqe->dma.length = length;
- wqe->dma.resid = length;
+ wqe->dma.resid = 0;
wqe->dma.num_sge = num_sge;
wqe->dma.cur_sge = 0;
wqe->dma.sge_offset = 0;
--
2.25.1
