[PATCH net-next 18/18] net/smc: add interface implementation of loopback device

Wen Gu
2023-09-19T14:44:02Z

This patch completes the specific implementation of loopback device
for the newly added SMC-D DMB-related interface.

The loopback device always provides mappable DMB because the device
users are in the same OS instance.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
---
net/smc/smc_loopback.c | 105 ++++++++++++++++++++++++++++++++++++++++++++-----
net/smc/smc_loopback.h | 5 +++
2 files changed, 100 insertions(+), 10 deletions(-)

diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c
index 650561b..611998b 100644
--- a/net/smc/smc_loopback.c
+++ b/net/smc/smc_loopback.c
@@ -105,6 +105,7 @@ static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
}
dmb_node->len = dmb->dmb_len;
dmb_node->dma_addr = (dma_addr_t)dmb_node->cpu_addr;
+ refcount_set(&dmb_node->refcnt, 1);

again:
/* add new dmb into hash table */
@@ -118,6 +119,7 @@ static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
}
hash_add(ldev->dmb_ht, &dmb_node->list, dmb_node->token);
write_unlock(&ldev->dmb_ht_lock);
+ atomic_inc(&ldev->dmb_cnt);

dmb->sba_idx = dmb_node->sba_idx;
dmb->dmb_tok = dmb_node->token;
@@ -139,28 +141,98 @@ static int smc_lo_unregister_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
struct smc_lo_dev *ldev = smcd->priv;

- /* remove dmb from hash table */
- write_lock(&ldev->dmb_ht_lock);
+ /* find dmb from hash table */
+ read_lock(&ldev->dmb_ht_lock);
hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
if (tmp_node->token == dmb->dmb_tok) {
dmb_node = tmp_node;
+ dmb_node->freeing = 1;
break;
}
}
if (!dmb_node) {
- write_unlock(&ldev->dmb_ht_lock);
+ read_unlock(&ldev->dmb_ht_lock);
return -EINVAL;
}
+ read_unlock(&ldev->dmb_ht_lock);
+
+ /* wait for dmb refcnt to be 0 */
+ if (!refcount_dec_and_test(&dmb_node->refcnt))
+ wait_event(ldev->dmbs_release, !refcount_read(&dmb_node->refcnt));
+
+ /* remove dmb from hash table */
+ write_lock(&ldev->dmb_ht_lock);
hash_del(&dmb_node->list);
write_unlock(&ldev->dmb_ht_lock);

clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
+
kfree(dmb_node->cpu_addr);
kfree(dmb_node);

+ if (atomic_dec_and_test(&ldev->dmb_cnt))
+ wake_up(&ldev->ldev_release);
+ return 0;
+}
+
+static int smc_lo_attach_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
+{
+ struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
+ struct smc_lo_dev *ldev = smcd->priv;
+
+ /* find dmb_node according to dmb->dmb_tok */
+ read_lock(&ldev->dmb_ht_lock);
+ hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
+ if (tmp_node->token == dmb->dmb_tok && !tmp_node->freeing) {
+ dmb_node = tmp_node;
+ break;
+ }
+ }
+ if (!dmb_node) {
+ read_unlock(&ldev->dmb_ht_lock);
+ return -EINVAL;
+ }
+ refcount_inc(&dmb_node->refcnt);
+ read_unlock(&ldev->dmb_ht_lock);
+
+ /* provide dmb information */
+ dmb->sba_idx = dmb_node->sba_idx;
+ dmb->dmb_tok = dmb_node->token;
+ dmb->cpu_addr = dmb_node->cpu_addr;
+ dmb->dma_addr = dmb_node->dma_addr;
+ dmb->dmb_len = dmb_node->len;
return 0;
}

+static int smc_lo_detach_dmb(struct smcd_dev *smcd, u64 token)
+{
+ struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
+ struct smc_lo_dev *ldev = smcd->priv;
+
+ /* find dmb_node according to dmb->dmb_tok */
+ read_lock(&ldev->dmb_ht_lock);
+ hash_for_each_possible(ldev->dmb_ht, tmp_node, list, token) {
+ if (tmp_node->token == token) {
+ dmb_node = tmp_node;
+ break;
+ }
+ }
+ if (!dmb_node) {
+ read_unlock(&ldev->dmb_ht_lock);
+ return -EINVAL;
+ }
+ read_unlock(&ldev->dmb_ht_lock);
+
+ if (refcount_dec_and_test(&dmb_node->refcnt))
+ wake_up_all(&ldev->dmbs_release);
+ return 0;
+}
+
+static int smc_lo_get_dev_attr(struct smcd_dev *smcd)
+{
+ return BIT(ISM_ATTR_DMB_MAP);
+}
+
static int smc_lo_add_vlan_id(struct smcd_dev *smcd, u64 vlan_id)
{
return -EOPNOTSUPP;
@@ -193,7 +265,15 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok, unsigned int idx
{
struct smc_lo_dmb_node *rmb_node = NULL, *tmp_node;
struct smc_lo_dev *ldev = smcd->priv;
-
+ struct smc_connection *conn;
+
+ if (!sf) {
+ /* local sndbuf shares the same physical memory with
+ * peer RMB, so no need to copy data from local sndbuf
+ * to peer RMB.
+ */
+ return 0;
+ }
read_lock(&ldev->dmb_ht_lock);
hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
if (tmp_node->token == dmb_tok) {
@@ -209,13 +289,10 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok, unsigned int idx

memcpy((char *)rmb_node->cpu_addr + offset, data, size);

- if (sf) {
- struct smc_connection *conn =
- smcd->conn[rmb_node->sba_idx];
+ conn = smcd->conn[rmb_node->sba_idx];
+ if (conn && !conn->killed)
+ smcd_cdc_rx_handler(conn);

- if (conn && !conn->killed)
- smcd_cdc_rx_handler(conn);
- }
return 0;
}

@@ -252,6 +329,8 @@ static struct device *smc_lo_get_dev(struct smcd_dev *smcd)
.query_remote_gid = smc_lo_query_rgid,
.register_dmb = smc_lo_register_dmb,
.unregister_dmb = smc_lo_unregister_dmb,
+ .attach_dmb = smc_lo_attach_dmb,
+ .detach_dmb = smc_lo_detach_dmb,
.add_vlan_id = smc_lo_add_vlan_id,
.del_vlan_id = smc_lo_del_vlan_id,
.set_vlan_required = smc_lo_set_vlan_required,
@@ -263,6 +342,7 @@ static struct device *smc_lo_get_dev(struct smcd_dev *smcd)
.get_local_gid = smc_lo_get_local_gid,
.get_chid = smc_lo_get_chid,
.get_dev = smc_lo_get_dev,
+ .get_dev_attr = smc_lo_get_dev_attr,
};

static struct smcd_dev *smcd_lo_alloc_dev(const struct smcd_ops *ops,
@@ -342,6 +422,9 @@ static int smc_lo_dev_init(struct smc_lo_dev *ldev)
smc_lo_generate_id(ldev);
rwlock_init(&ldev->dmb_ht_lock);
hash_init(ldev->dmb_ht);
+ atomic_set(&ldev->dmb_cnt, 0);
+ init_waitqueue_head(&ldev->dmbs_release);
+ init_waitqueue_head(&ldev->ldev_release);

return smcd_lo_register_dev(ldev);
}
@@ -375,6 +458,8 @@ static int smc_lo_dev_probe(void)
static void smc_lo_dev_exit(struct smc_lo_dev *ldev)
{
smcd_lo_unregister_dev(ldev);
+ if (atomic_read(&ldev->dmb_cnt))
+ wait_event(ldev->ldev_release, !atomic_read(&ldev->dmb_cnt));
}

static void smc_lo_dev_remove(void)
diff --git a/net/smc/smc_loopback.h b/net/smc/smc_loopback.h
index 943424f..506e524 100644
--- a/net/smc/smc_loopback.h
+++ b/net/smc/smc_loopback.h
@@ -29,6 +29,8 @@ struct smc_lo_dmb_node {
u32 sba_idx;
void *cpu_addr;
dma_addr_t dma_addr;
+ refcount_t refcnt;
+ u8 freeing : 1;
};

struct smc_lo_dev {
@@ -39,6 +41,9 @@ struct smc_lo_dev {
DECLARE_BITMAP(sba_idx_mask, SMC_LODEV_MAX_DMBS);
rwlock_t dmb_ht_lock;
DECLARE_HASHTABLE(dmb_ht, SMC_LODEV_DMBS_HASH_BITS);
+ atomic_t dmb_cnt;
+ wait_queue_head_t dmbs_release;
+ wait_queue_head_t ldev_release;
};

int smc_loopback_init(void);
--
1.8.3.1