From b8ded9de8db34dd209a3dece94cf54fc414e78f7 Mon Sep 17 00:00:00 2001 From: Karsten Graul Date: Sat, 30 May 2020 16:42:37 +0200 Subject: [PATCH] net/smc: pre-fetch send buffer outside of send_lock 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 Reviewed-by: Ursula Braun Signed-off-by: David S. Miller --- net/smc/smc_cdc.c | 10 +++------- net/smc/smc_cdc.h | 4 +++- net/smc/smc_core.c | 18 +++++++++++++++--- 3 files changed, 21 insertions(+), 11 deletions(-) diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c index b2b85e1be72c..a47e8855e045 100644 --- a/net/smc/smc_cdc.c +++ b/net/smc/smc_cdc.c @@ -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; diff --git a/net/smc/smc_cdc.h b/net/smc/smc_cdc.h index 2ddcc5fb5ceb..0a0a89abd38b 100644 --- a/net/smc/smc_cdc.h +++ b/net/smc/smc_cdc.h @@ -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); diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 65de700e1f17..7964a21e5e6f 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -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) { -- GitLab