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net/smc: pre-fetch send buffer outside of send_lock

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Pre-fetch send buffer for the CDC validation message before entering the
send_lock. Without that the send call might fail with -EBUSY because
there are no free buffers and waiting for buffers is not possible under
send_lock.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Karsten Graul 2020-05-30 16:42:37 +02:00 committed by David S. Miller
parent b86a372201
commit b8ded9de8d
3 changed files with 21 additions and 11 deletions
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10
net/smc/smc_cdc.c
View File

@ -116,19 +116,15 @@ int smc_cdc_msg_send(struct smc_connection *conn,
}
/* send a validation msg indicating the move of a conn to an other QP link */
int smcr_cdc_msg_send_validation(struct smc_connection *conn)
int smcr_cdc_msg_send_validation(struct smc_connection *conn,
struct smc_cdc_tx_pend *pend,
struct smc_wr_buf *wr_buf)
{
struct smc_host_cdc_msg *local = &conn->local_tx_ctrl;
struct smc_link *link = conn->lnk;
struct smc_cdc_tx_pend *pend;
struct smc_wr_buf *wr_buf;
struct smc_cdc_msg *peer;
int rc;
rc = smc_cdc_get_free_slot(conn, link, &wr_buf, NULL, &pend);
if (rc)
return rc;
peer = (struct smc_cdc_msg *)wr_buf;
peer->common.type = local->common.type;
peer->len = local->len;

4
net/smc/smc_cdc.h
View File

@ -296,7 +296,9 @@ int smc_cdc_msg_send(struct smc_connection *conn, struct smc_wr_buf *wr_buf,
struct smc_cdc_tx_pend *pend);
int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);
int smcd_cdc_msg_send(struct smc_connection *conn);
int smcr_cdc_msg_send_validation(struct smc_connection *conn);
int smcr_cdc_msg_send_validation(struct smc_connection *conn,
struct smc_cdc_tx_pend *pend,
struct smc_wr_buf *wr_buf);
int smc_cdc_init(void) __init;
void smcd_cdc_rx_init(struct smc_connection *conn);

18
net/smc/smc_core.c
View File

@ -483,7 +483,8 @@ static int smc_write_space(struct smc_connection *conn)
return space;
}
static int smc_switch_cursor(struct smc_sock *smc)
static int smc_switch_cursor(struct smc_sock *smc, struct smc_cdc_tx_pend *pend,
struct smc_wr_buf *wr_buf)
{
struct smc_connection *conn = &smc->conn;
union smc_host_cursor cons, fin;
@ -520,11 +521,14 @@ static int smc_switch_cursor(struct smc_sock *smc)
if (smc->sk.sk_state != SMC_INIT &&
smc->sk.sk_state != SMC_CLOSED) {
rc = smcr_cdc_msg_send_validation(conn);
rc = smcr_cdc_msg_send_validation(conn, pend, wr_buf);
if (!rc) {
schedule_delayed_work(&conn->tx_work, 0);
smc->sk.sk_data_ready(&smc->sk);
}
} else {
smc_wr_tx_put_slot(conn->lnk,
(struct smc_wr_tx_pend_priv *)pend);
}
return rc;
}
@ -533,7 +537,9 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
struct smc_link *from_lnk, bool is_dev_err)
{
struct smc_link *to_lnk = NULL;
struct smc_cdc_tx_pend *pend;
struct smc_connection *conn;
struct smc_wr_buf *wr_buf;
struct smc_sock *smc;
struct rb_node *node;
int i, rc = 0;
@ -582,10 +588,16 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
}
sock_hold(&smc->sk);
read_unlock_bh(&lgr->conns_lock);
/* pre-fetch buffer outside of send_lock, might sleep */
rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend);
if (rc) {
smcr_link_down_cond_sched(to_lnk);
return NULL;
}
/* avoid race with smcr_tx_sndbuf_nonempty() */
spin_lock_bh(&conn->send_lock);
conn->lnk = to_lnk;
rc = smc_switch_cursor(smc);
rc = smc_switch_cursor(smc, pend, wr_buf);
spin_unlock_bh(&conn->send_lock);
sock_put(&smc->sk);
if (rc) {