[RFC PATCH net-next v5 6/9] net/smc: Introudce interfaces for DMB attach and detach

[Wen Gu <guwen@linux.alibaba.com>]

This patch extends smcd_ops, adding two more semantic for SMC-D DMB:

- attach_dmb:
  Attach an already registered DMB to a specific buf_desc, so that we
  can refer to the DMB through this buf_desc.

- detach_dmb:
  Reverse operation of attach_dmb. detach the DMB from the buf_desc.

This interface extension is to prepare for the avoidance of memory
copy from sndbuf to RMB with SMC-D device whose DMBs has ISM_DMB_MAPPABLE
attribute.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
---
 include/net/smc.h |  2 ++
 net/smc/smc_ism.c | 31 +++++++++++++++++++++++++++++++
 net/smc/smc_ism.h |  2 ++
 3 files changed, 35 insertions(+)

diff --git a/include/net/smc.h b/include/net/smc.h
index e39ac41..0132522 100644
--- a/include/net/smc.h
+++ b/include/net/smc.h
@@ -67,6 +67,8 @@ struct smcd_ops {
 	int (*register_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb,
 			    void *client_priv);
 	int (*unregister_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb);
+	int (*attach_dmb)(struct smcd_dev *dev, struct smcd_dmb *dmb);
+	int (*detach_dmb)(struct smcd_dev *dev, u64 token);
 	int (*add_vlan_id)(struct smcd_dev *dev, u64 vlan_id);
 	int (*del_vlan_id)(struct smcd_dev *dev, u64 vlan_id);
 	int (*set_vlan_required)(struct smcd_dev *dev);
diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
index 1d97e77..925af13 100644
--- a/net/smc/smc_ism.c
+++ b/net/smc/smc_ism.c
@@ -243,6 +243,37 @@ int smc_ism_register_dmb(struct smc_link_group *lgr, int dmb_len,
 	return rc;
 }
 
+int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token,
+		       struct smc_buf_desc *dmb_desc)
+{
+	struct smcd_dmb dmb;
+	int rc = 0;
+
+	memset(&dmb, 0, sizeof(dmb));
+	dmb.dmb_tok = token;
+
+	if (!dev->ops->attach_dmb)
+		return -EINVAL;
+
+	rc = dev->ops->attach_dmb(dev, &dmb);
+	if (!rc) {
+		dmb_desc->sba_idx = dmb.sba_idx;
+		dmb_desc->token = dmb.dmb_tok;
+		dmb_desc->cpu_addr = dmb.cpu_addr;
+		dmb_desc->dma_addr = dmb.dma_addr;
+		dmb_desc->len = dmb.dmb_len;
+	}
+	return rc;
+}
+
+int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token)
+{
+	if (!dev->ops->detach_dmb)
+		return -EINVAL;
+
+	return dev->ops->detach_dmb(dev, token);
+}
+
 static int smc_nl_handle_smcd_dev(struct smcd_dev *smcd,
 				  struct sk_buff *skb,
 				  struct netlink_callback *cb)
diff --git a/net/smc/smc_ism.h b/net/smc/smc_ism.h
index 0b1913a..31eb010 100644
--- a/net/smc/smc_ism.h
+++ b/net/smc/smc_ism.h
@@ -41,6 +41,8 @@ int smc_ism_register_dmb(struct smc_link_group *lgr, int buf_size,
 			 struct smc_buf_desc *dmb_desc);
 int smc_ism_unregister_dmb(struct smcd_dev *dev, struct smc_buf_desc *dmb_desc);
 bool smc_ism_dmb_mappable(struct smcd_dev *smcd);
+int smc_ism_attach_dmb(struct smcd_dev *dev, u64 token, struct smc_buf_desc *dmb_desc);
+int smc_ism_detach_dmb(struct smcd_dev *dev, u64 token);
 int smc_ism_signal_shutdown(struct smc_link_group *lgr);
 void smc_ism_get_system_eid(u8 **eid);
 u16 smc_ism_get_chid(struct smcd_dev *dev);
-- 
1.8.3.1