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net/smc: implement DMB-merged operations of loopback-ism
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This implements operations related to merging sndbuf with peer DMB in
loopback-ism. The DMB won't be freed until no sndbuf is attached to it.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>
Reviewed-and-tested-by: Jan Karcher <jaka@linux.ibm.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Wen Gu authored and Paolo Abeni committed Apr 30, 2024
1 parent cc0ab80 commit c3a910f
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Showing 2 changed files with 108 additions and 15 deletions.
120 changes: 105 additions & 15 deletions net/smc/smc_loopback.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include "smc_loopback.h"

#define SMC_LO_V2_CAPABLE 0x1 /* loopback-ism acts as ISMv2 */
#define SMC_LO_SUPPORT_NOCOPY 0x1
#define SMC_DMA_ADDR_INVALID (~(dma_addr_t)0)

static const char smc_lo_dev_name[] = "loopback-ism";
Expand Down Expand Up @@ -81,6 +82,7 @@ static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
goto err_node;
}
dmb_node->dma_addr = SMC_DMA_ADDR_INVALID;
refcount_set(&dmb_node->refcnt, 1);

again:
/* add new dmb into hash table */
Expand All @@ -94,6 +96,7 @@ 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_bh(&ldev->dmb_ht_lock);
atomic_inc(&ldev->dmb_cnt);

dmb->sba_idx = dmb_node->sba_idx;
dmb->dmb_tok = dmb_node->token;
Expand All @@ -110,30 +113,106 @@ static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
return rc;
}

static void __smc_lo_unregister_dmb(struct smc_lo_dev *ldev,
struct smc_lo_dmb_node *dmb_node)
{
/* remove dmb from hash table */
write_lock_bh(&ldev->dmb_ht_lock);
hash_del(&dmb_node->list);
write_unlock_bh(&ldev->dmb_ht_lock);

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

if (atomic_dec_and_test(&ldev->dmb_cnt))
wake_up(&ldev->ldev_release);
}

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_bh(&ldev->dmb_ht_lock);
/* find dmb from hash table */
read_lock_bh(&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;
break;
}
}
if (!dmb_node) {
write_unlock_bh(&ldev->dmb_ht_lock);
read_unlock_bh(&ldev->dmb_ht_lock);
return -EINVAL;
}
hash_del(&dmb_node->list);
write_unlock_bh(&ldev->dmb_ht_lock);
read_unlock_bh(&ldev->dmb_ht_lock);

clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
kfree(dmb_node->cpu_addr);
kfree(dmb_node);
if (refcount_dec_and_test(&dmb_node->refcnt))
__smc_lo_unregister_dmb(ldev, dmb_node);
return 0;
}

static int smc_lo_support_dmb_nocopy(struct smcd_dev *smcd)
{
return SMC_LO_SUPPORT_NOCOPY;
}

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_bh(&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;
break;
}
}
if (!dmb_node) {
read_unlock_bh(&ldev->dmb_ht_lock);
return -EINVAL;
}
read_unlock_bh(&ldev->dmb_ht_lock);

if (!refcount_inc_not_zero(&dmb_node->refcnt))
/* the dmb is being unregistered, but has
* not been removed from the hash table.
*/
return -EINVAL;

/* 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_bh(&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_bh(&ldev->dmb_ht_lock);
return -EINVAL;
}
read_unlock_bh(&ldev->dmb_ht_lock);

if (refcount_dec_and_test(&dmb_node->refcnt))
__smc_lo_unregister_dmb(ldev, dmb_node);
return 0;
}

Expand All @@ -145,6 +224,12 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok,
struct smc_lo_dev *ldev = smcd->priv;
struct smc_connection *conn;

if (!sf)
/* since sndbuf is merged with peer DMB, there is
* no need to copy data from sndbuf to peer DMB.
*/
return 0;

read_lock_bh(&ldev->dmb_ht_lock);
hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
if (tmp_node->token == dmb_tok) {
Expand All @@ -159,13 +244,10 @@ static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok,
memcpy((char *)rmb_node->cpu_addr + offset, data, size);
read_unlock_bh(&ldev->dmb_ht_lock);

if (sf) {
conn = smcd->conn[rmb_node->sba_idx];
if (conn && !conn->killed)
tasklet_schedule(&conn->rx_tsklet);
else
return -EPIPE;
}
conn = smcd->conn[rmb_node->sba_idx];
if (!conn || conn->killed)
return -EPIPE;
tasklet_schedule(&conn->rx_tsklet);
return 0;
}

Expand Down Expand Up @@ -197,6 +279,9 @@ static const struct smcd_ops lo_ops = {
.query_remote_gid = smc_lo_query_rgid,
.register_dmb = smc_lo_register_dmb,
.unregister_dmb = smc_lo_unregister_dmb,
.support_dmb_nocopy = smc_lo_support_dmb_nocopy,
.attach_dmb = smc_lo_attach_dmb,
.detach_dmb = smc_lo_detach_dmb,
.add_vlan_id = NULL,
.del_vlan_id = NULL,
.set_vlan_required = NULL,
Expand Down Expand Up @@ -275,12 +360,17 @@ static int smc_lo_dev_init(struct smc_lo_dev *ldev)
smc_lo_generate_ids(ldev);
rwlock_init(&ldev->dmb_ht_lock);
hash_init(ldev->dmb_ht);
atomic_set(&ldev->dmb_cnt, 0);
init_waitqueue_head(&ldev->ldev_release);

return smcd_lo_register_dev(ldev);
}

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_release(struct device *dev)
Expand Down
3 changes: 3 additions & 0 deletions net/smc/smc_loopback.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,16 +30,19 @@ struct smc_lo_dmb_node {
u32 sba_idx;
void *cpu_addr;
dma_addr_t dma_addr;
refcount_t refcnt;
};

struct smc_lo_dev {
struct smcd_dev *smcd;
struct device dev;
u16 chid;
struct smcd_gid local_gid;
atomic_t dmb_cnt;
rwlock_t dmb_ht_lock;
DECLARE_BITMAP(sba_idx_mask, SMC_LO_MAX_DMBS);
DECLARE_HASHTABLE(dmb_ht, SMC_LO_DMBS_HASH_BITS);
wait_queue_head_t ldev_release;
};

int smc_loopback_init(void);
Expand Down

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