Re: [PATCH v4 10/25] ibtrs: server: main functionality

[Bart Van Assche <bvanassche@acm.org>]

On 6/20/19 8:03 AM, Jack Wang wrote:
> +module_param_named(max_chunk_size, max_chunk_size, int, 0444);
> +MODULE_PARM_DESC(max_chunk_size,
> +		 "Max size for each IO request, when change the unit is in byte"
> +		 " (default: " __stringify(DEFAULT_MAX_CHUNK_SIZE_KB) "KB)");

Where can I find the definition of DEFAULT_MAX_CHUNK_SIZE_KB?

> +static char cq_affinity_list[256] = "";

No empty initializers for file-scope variables please.

> +	pr_info("cq_affinity_list changed to %*pbl\n",
> +		cpumask_pr_args(&cq_affinity_mask));

Should this pr_info() call perhaps be changed into pr_debug()?

> +static bool __ibtrs_srv_change_state(struct ibtrs_srv_sess *sess,
> +				     enum ibtrs_srv_state new_state)
> +{
> +	enum ibtrs_srv_state old_state;
> +	bool changed = false;
> +
> +	old_state = sess->state;
> +	switch (new_state) {

Please add a lockdep_assert_held() statement that checks whether calls 
of this function are serialized properly.

> +/**
> + * rdma_write_sg() - response on successful READ request
> + */
> +static int rdma_write_sg(struct ibtrs_srv_op *id)
> +{
> +	struct ibtrs_srv_sess *sess = to_srv_sess(id->con->c.sess);
> +	dma_addr_t dma_addr = sess->dma_addr[id->msg_id];
> +	struct ibtrs_srv *srv = sess->srv;
> +	struct ib_send_wr inv_wr, imm_wr;
> +	struct ib_rdma_wr *wr = NULL;
> +	const struct ib_send_wr *bad_wr;
> +	enum ib_send_flags flags;
> +	size_t sg_cnt;
> +	int err, i, offset;
> +	bool need_inval;
> +	u32 rkey = 0;
> +
> +	sg_cnt = le16_to_cpu(id->rd_msg->sg_cnt);
> +	need_inval = le16_to_cpu(id->rd_msg->flags) & IBTRS_MSG_NEED_INVAL_F;
> +	if (unlikely(!sg_cnt))
> +		return -EINVAL;
> +
> +	offset = 0;
> +	for (i = 0; i < sg_cnt; i++) {
> +		struct ib_sge *list;
> +
> +		wr		= &id->tx_wr[i];
> +		list		= &id->tx_sg[i];
> +		list->addr	= dma_addr + offset;
> +		list->length	= le32_to_cpu(id->rd_msg->desc[i].len);
> +
> +		/* WR will fail with length error
> +		 * if this is 0
> +		 */
> +		if (unlikely(list->length == 0)) {
> +			ibtrs_err(sess, "Invalid RDMA-Write sg list length 0\n");
> +			return -EINVAL;
> +		}
> +
> +		list->lkey = sess->s.dev->ib_pd->local_dma_lkey;
> +		offset += list->length;
> +
> +		wr->wr.wr_cqe	= &io_comp_cqe;
> +		wr->wr.sg_list	= list;
> +		wr->wr.num_sge	= 1;
> +		wr->remote_addr	= le64_to_cpu(id->rd_msg->desc[i].addr);
> +		wr->rkey	= le32_to_cpu(id->rd_msg->desc[i].key);
> +		if (rkey == 0)
> +			rkey = wr->rkey;
> +		else
> +			/* Only one key is actually used */
> +			WARN_ON_ONCE(rkey != wr->rkey);
> +
> +		if (i < (sg_cnt - 1))
> +			wr->wr.next = &id->tx_wr[i + 1].wr;
> +		else if (need_inval)
> +			wr->wr.next = &inv_wr;
> +		else
> +			wr->wr.next = &imm_wr;
> +
> +		wr->wr.opcode = IB_WR_RDMA_WRITE;
> +		wr->wr.ex.imm_data = 0;
> +		wr->wr.send_flags  = 0;
> +	}
> +	/*
> +	 * From time to time we have to post signalled sends,
> +	 * or send queue will fill up and only QP reset can help.
> +	 */
> +	flags = atomic_inc_return(&id->con->wr_cnt) % srv->queue_depth ?
> +			0 : IB_SEND_SIGNALED;
> +
> +	if (need_inval) {
> +		inv_wr.next = &imm_wr;
> +		inv_wr.wr_cqe = &io_comp_cqe;
> +		inv_wr.sg_list = NULL;
> +		inv_wr.num_sge = 0;
> +		inv_wr.opcode = IB_WR_SEND_WITH_INV;
> +		inv_wr.send_flags = 0;
> +		inv_wr.ex.invalidate_rkey = rkey;
> +	}
> +	imm_wr.next = NULL;
> +	imm_wr.wr_cqe = &io_comp_cqe;
> +	imm_wr.sg_list = NULL;
> +	imm_wr.num_sge = 0;
> +	imm_wr.opcode = IB_WR_RDMA_WRITE_WITH_IMM;
> +	imm_wr.send_flags = flags;
> +	imm_wr.ex.imm_data = cpu_to_be32(ibtrs_to_io_rsp_imm(id->msg_id,
> +							     0, need_inval));
> +
> +	ib_dma_sync_single_for_device(sess->s.dev->ib_dev, dma_addr,
> +				      offset, DMA_BIDIRECTIONAL);
> +
> +	err = ib_post_send(id->con->c.qp, &id->tx_wr[0].wr, &bad_wr);
> +	if (unlikely(err))
> +		ibtrs_err(sess,
> +			  "Posting RDMA-Write-Request to QP failed, err: %d\n",
> +			  err);
> +
> +	return err;
> +}

All other RDMA server implementations use rdma_rw_ctx_init() and 
rdma_rw_ctx_wrs(). Please use these functions in IBTRS too.

> +static void ibtrs_srv_hb_err_handler(struct ibtrs_con *c, int err)
> +{
> +	(void)err;
> +	close_sess(to_srv_sess(c->sess));
> +}

Is the (void)err statement really necessary?

> +static int ibtrs_srv_rdma_init(struct ibtrs_srv_ctx *ctx, unsigned int port)
> +{
> +	struct sockaddr_in6 sin = {
> +		.sin6_family	= AF_INET6,
> +		.sin6_addr	= IN6ADDR_ANY_INIT,
> +		.sin6_port	= htons(port),
> +	};
> +	struct sockaddr_ib sib = {
> +		.sib_family			= AF_IB,
> +		.sib_addr.sib_subnet_prefix	= 0ULL,
> +		.sib_addr.sib_interface_id	= 0ULL,
> +		.sib_sid	= cpu_to_be64(RDMA_IB_IP_PS_IB | port),
> +		.sib_sid_mask	= cpu_to_be64(0xffffffffffffffffULL),
> +		.sib_pkey	= cpu_to_be16(0xffff),
> +	};
> +	struct rdma_cm_id *cm_ip, *cm_ib;
> +	int ret;
> +
> +	/*
> +	 * We accept both IPoIB and IB connections, so we need to keep
> +	 * two cm id's, one for each socket type and port space.
> +	 * If the cm initialization of one of the id's fails, we abort
> +	 * everything.
> +	 */
> +	cm_ip = ibtrs_srv_cm_init(ctx, (struct sockaddr *)&sin, RDMA_PS_TCP);
> +	if (unlikely(IS_ERR(cm_ip)))
> +		return PTR_ERR(cm_ip);
> +
> +	cm_ib = ibtrs_srv_cm_init(ctx, (struct sockaddr *)&sib, RDMA_PS_IB);
> +	if (unlikely(IS_ERR(cm_ib))) {
> +		ret = PTR_ERR(cm_ib);
> +		goto free_cm_ip;
> +	}
> +
> +	ctx->cm_id_ip = cm_ip;
> +	ctx->cm_id_ib = cm_ib;
> +
> +	return 0;
> +
> +free_cm_ip:
> +	rdma_destroy_id(cm_ip);
> +
> +	return ret;
> +}

Will the above work if CONFIG_IPV6=n?

> +static int __init ibtrs_server_init(void)
> +{
> +	int err;
> +
> +	if (!strlen(cq_affinity_list))
> +		init_cq_affinity();

Is the above if-test useful? Can that if-test be left out?

Thanks,

Bart.