net/smc: switch connections to alternate link
Add smc_switch_conns() to switch all connections from a link that is going down. Find an other link to switch the connections to, and switch each connection to the new link. smc_switch_cursor() updates the cursors of a connection to the state of the last successfully sent CDC message. When there is no link to switch to, terminate the link group. Call smc_switch_conns() when a link is going down. And with the possibility that links of connections can switch adapt CDC and TX functions to detect and handle link switches. 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>
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@ -56,11 +56,11 @@ static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
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}
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int smc_cdc_get_free_slot(struct smc_connection *conn,
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struct smc_link *link,
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struct smc_wr_buf **wr_buf,
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struct smc_rdma_wr **wr_rdma_buf,
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struct smc_cdc_tx_pend **pend)
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{
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struct smc_link *link = conn->lnk;
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int rc;
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rc = smc_wr_tx_get_free_slot(link, smc_cdc_tx_handler, wr_buf,
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@ -119,13 +119,27 @@ static int smcr_cdc_get_slot_and_msg_send(struct smc_connection *conn)
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{
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struct smc_cdc_tx_pend *pend;
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struct smc_wr_buf *wr_buf;
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struct smc_link *link;
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bool again = false;
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int rc;
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rc = smc_cdc_get_free_slot(conn, &wr_buf, NULL, &pend);
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again:
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link = conn->lnk;
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rc = smc_cdc_get_free_slot(conn, link, &wr_buf, NULL, &pend);
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if (rc)
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return rc;
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spin_lock_bh(&conn->send_lock);
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if (link != conn->lnk) {
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/* link of connection changed, try again one time*/
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spin_unlock_bh(&conn->send_lock);
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smc_wr_tx_put_slot(link,
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(struct smc_wr_tx_pend_priv *)pend);
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if (again)
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return -ENOLINK;
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again = true;
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goto again;
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}
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rc = smc_cdc_msg_send(conn, wr_buf, pend);
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spin_unlock_bh(&conn->send_lock);
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return rc;
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@ -304,6 +304,7 @@ struct smc_cdc_tx_pend {
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};
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int smc_cdc_get_free_slot(struct smc_connection *conn,
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struct smc_link *link,
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struct smc_wr_buf **wr_buf,
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struct smc_rdma_wr **wr_rdma_buf,
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struct smc_cdc_tx_pend **pend);
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@ -432,6 +432,135 @@ out:
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return rc;
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}
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static int smc_write_space(struct smc_connection *conn)
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{
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int buffer_len = conn->peer_rmbe_size;
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union smc_host_cursor prod;
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union smc_host_cursor cons;
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int space;
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smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn);
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smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
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/* determine rx_buf space */
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space = buffer_len - smc_curs_diff(buffer_len, &cons, &prod);
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return space;
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}
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static int smc_switch_cursor(struct smc_sock *smc)
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{
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struct smc_connection *conn = &smc->conn;
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union smc_host_cursor cons, fin;
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int rc = 0;
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int diff;
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smc_curs_copy(&conn->tx_curs_sent, &conn->tx_curs_fin, conn);
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smc_curs_copy(&fin, &conn->local_tx_ctrl_fin, conn);
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/* set prod cursor to old state, enforce tx_rdma_writes() */
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smc_curs_copy(&conn->local_tx_ctrl.prod, &fin, conn);
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smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
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if (smc_curs_comp(conn->peer_rmbe_size, &cons, &fin) < 0) {
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/* cons cursor advanced more than fin, and prod was set
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* fin above, so now prod is smaller than cons. Fix that.
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*/
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diff = smc_curs_diff(conn->peer_rmbe_size, &fin, &cons);
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smc_curs_add(conn->sndbuf_desc->len,
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&conn->tx_curs_sent, diff);
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smc_curs_add(conn->sndbuf_desc->len,
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&conn->tx_curs_fin, diff);
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smp_mb__before_atomic();
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atomic_add(diff, &conn->sndbuf_space);
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smp_mb__after_atomic();
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smc_curs_add(conn->peer_rmbe_size,
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&conn->local_tx_ctrl.prod, diff);
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smc_curs_add(conn->peer_rmbe_size,
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&conn->local_tx_ctrl_fin, diff);
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}
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/* recalculate, value is used by tx_rdma_writes() */
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atomic_set(&smc->conn.peer_rmbe_space, smc_write_space(conn));
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if (smc->sk.sk_state != SMC_INIT &&
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smc->sk.sk_state != SMC_CLOSED) {
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/* tbd: call rc = smc_cdc_get_slot_and_msg_send(conn); */
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if (!rc) {
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schedule_delayed_work(&conn->tx_work, 0);
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smc->sk.sk_data_ready(&smc->sk);
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}
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}
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return rc;
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}
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struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
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struct smc_link *from_lnk, bool is_dev_err)
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{
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struct smc_link *to_lnk = NULL;
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struct smc_connection *conn;
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struct smc_sock *smc;
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struct rb_node *node;
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int i, rc = 0;
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/* link is inactive, wake up tx waiters */
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smc_wr_wakeup_tx_wait(from_lnk);
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for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
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if (lgr->lnk[i].state != SMC_LNK_ACTIVE ||
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i == from_lnk->link_idx)
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continue;
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if (is_dev_err && from_lnk->smcibdev == lgr->lnk[i].smcibdev &&
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from_lnk->ibport == lgr->lnk[i].ibport) {
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continue;
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}
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to_lnk = &lgr->lnk[i];
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break;
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}
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if (!to_lnk) {
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smc_lgr_terminate_sched(lgr);
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return NULL;
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}
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again:
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read_lock_bh(&lgr->conns_lock);
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for (node = rb_first(&lgr->conns_all); node; node = rb_next(node)) {
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conn = rb_entry(node, struct smc_connection, alert_node);
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if (conn->lnk != from_lnk)
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continue;
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smc = container_of(conn, struct smc_sock, conn);
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/* conn->lnk not yet set in SMC_INIT state */
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if (smc->sk.sk_state == SMC_INIT)
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continue;
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if (smc->sk.sk_state == SMC_CLOSED ||
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smc->sk.sk_state == SMC_PEERCLOSEWAIT1 ||
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smc->sk.sk_state == SMC_PEERCLOSEWAIT2 ||
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smc->sk.sk_state == SMC_APPFINCLOSEWAIT ||
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smc->sk.sk_state == SMC_APPCLOSEWAIT1 ||
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smc->sk.sk_state == SMC_APPCLOSEWAIT2 ||
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smc->sk.sk_state == SMC_PEERFINCLOSEWAIT ||
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smc->sk.sk_state == SMC_PEERABORTWAIT ||
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smc->sk.sk_state == SMC_PROCESSABORT) {
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spin_lock_bh(&conn->send_lock);
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conn->lnk = to_lnk;
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spin_unlock_bh(&conn->send_lock);
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continue;
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}
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sock_hold(&smc->sk);
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read_unlock_bh(&lgr->conns_lock);
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/* avoid race with smcr_tx_sndbuf_nonempty() */
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spin_lock_bh(&conn->send_lock);
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conn->lnk = to_lnk;
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rc = smc_switch_cursor(smc);
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spin_unlock_bh(&conn->send_lock);
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sock_put(&smc->sk);
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if (rc) {
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smcr_link_down_cond_sched(to_lnk);
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return NULL;
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}
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goto again;
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}
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read_unlock_bh(&lgr->conns_lock);
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return to_lnk;
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}
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static void smcr_buf_unuse(struct smc_buf_desc *rmb_desc,
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struct smc_link_group *lgr)
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{
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@ -943,8 +1072,7 @@ static void smcr_link_down(struct smc_link *lnk)
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return;
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smc_ib_modify_qp_reset(lnk);
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to_lnk = NULL;
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/* tbd: call to_lnk = smc_switch_conns(lgr, lnk, true); */
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to_lnk = smc_switch_conns(lgr, lnk, true);
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if (!to_lnk) { /* no backup link available */
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smcr_link_clear(lnk);
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return;
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@ -380,6 +380,8 @@ void smcr_link_clear(struct smc_link *lnk);
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int smcr_buf_map_lgr(struct smc_link *lnk);
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int smcr_buf_reg_lgr(struct smc_link *lnk);
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int smcr_link_reg_rmb(struct smc_link *link, struct smc_buf_desc *rmb_desc);
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struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
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struct smc_link *from_lnk, bool is_dev_err);
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void smcr_link_down_cond(struct smc_link *lnk);
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void smcr_link_down_cond_sched(struct smc_link *lnk);
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@ -933,7 +933,7 @@ static void smc_llc_delete_asym_link(struct smc_link_group *lgr)
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return; /* no asymmetric link */
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if (!smc_link_downing(&lnk_asym->state))
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return;
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/* tbd: lnk_new = smc_switch_conns(lgr, lnk_asym, false); */
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lnk_new = smc_switch_conns(lgr, lnk_asym, false);
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smc_wr_tx_wait_no_pending_sends(lnk_asym);
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if (!lnk_new)
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goto out_free;
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@ -1195,7 +1195,7 @@ static void smc_llc_process_cli_delete_link(struct smc_link_group *lgr)
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smc_llc_send_message(lnk, &qentry->msg); /* response */
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if (smc_link_downing(&lnk_del->state)) {
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/* tbd: call smc_switch_conns(lgr, lnk_del, false); */
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smc_switch_conns(lgr, lnk_del, false);
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smc_wr_tx_wait_no_pending_sends(lnk_del);
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}
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smcr_link_clear(lnk_del);
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@ -1245,7 +1245,7 @@ static void smc_llc_process_srv_delete_link(struct smc_link_group *lgr)
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goto out; /* asymmetric link already deleted */
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if (smc_link_downing(&lnk_del->state)) {
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/* tbd: call smc_switch_conns(lgr, lnk_del, false); */
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smc_switch_conns(lgr, lnk_del, false);
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smc_wr_tx_wait_no_pending_sends(lnk_del);
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}
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if (!list_empty(&lgr->list)) {
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@ -482,12 +482,13 @@ static int smc_tx_rdma_writes(struct smc_connection *conn,
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static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
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{
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struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
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struct smc_link *link = conn->lnk;
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struct smc_rdma_wr *wr_rdma_buf;
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struct smc_cdc_tx_pend *pend;
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struct smc_wr_buf *wr_buf;
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int rc;
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rc = smc_cdc_get_free_slot(conn, &wr_buf, &wr_rdma_buf, &pend);
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rc = smc_cdc_get_free_slot(conn, link, &wr_buf, &wr_rdma_buf, &pend);
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if (rc < 0) {
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if (rc == -EBUSY) {
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struct smc_sock *smc =
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@ -505,10 +506,17 @@ static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
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}
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spin_lock_bh(&conn->send_lock);
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if (link != conn->lnk) {
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/* link of connection changed, tx_work will restart */
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smc_wr_tx_put_slot(link,
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(struct smc_wr_tx_pend_priv *)pend);
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rc = -ENOLINK;
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goto out_unlock;
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}
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if (!pflags->urg_data_present) {
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rc = smc_tx_rdma_writes(conn, wr_rdma_buf);
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if (rc) {
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smc_wr_tx_put_slot(conn->lnk,
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smc_wr_tx_put_slot(link,
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(struct smc_wr_tx_pend_priv *)pend);
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goto out_unlock;
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}
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