net/smc: improve delete link processing

Send an orderly DELETE LINK request before termination of a link group,
add support for client triggered DELETE LINK processing. And send a
disorderly DELETE LINK before module is unloaded.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc_core.c

@@ -30,6 +30,7 @@
 #define SMC_LGR_NUM_INCR		256
 #define SMC_LGR_FREE_DELAY_SERV		(600 * HZ)
 #define SMC_LGR_FREE_DELAY_CLNT		(SMC_LGR_FREE_DELAY_SERV + 10 * HZ)
+#define SMC_LGR_FREE_DELAY_FAST		(8 * HZ)
 
 static struct smc_lgr_list smc_lgr_list = {	/* established link groups */
 	.lock = __SPIN_LOCK_UNLOCKED(smc_lgr_list.lock),
@@ -51,6 +52,11 @@ static void smc_lgr_schedule_free_work(struct smc_link_group *lgr)
 			 SMC_LGR_FREE_DELAY_CLNT : SMC_LGR_FREE_DELAY_SERV);
 }
 
+void smc_lgr_schedule_free_work_fast(struct smc_link_group *lgr)
+{
+	mod_delayed_work(system_wq, &lgr->free_work, SMC_LGR_FREE_DELAY_FAST);
+}
+
 /* Register connection's alert token in our lookup structure.
  * To use rbtrees we have to implement our own insert core.
  * Requires @conns_lock
@@ -133,6 +139,20 @@ static void smc_lgr_unregister_conn(struct smc_connection *conn)
 	smc_lgr_schedule_free_work(lgr);
 }
 
+/* Send delete link, either as client to request the initiation
+ * of the DELETE LINK sequence from server; or as server to
+ * initiate the delete processing. See smc_llc_rx_delete_link().
+ */
+static int smc_link_send_delete(struct smc_link *lnk)
+{
+	if (lnk->state == SMC_LNK_ACTIVE &&
+	    !smc_llc_send_delete_link(lnk, SMC_LLC_REQ, true)) {
+		smc_llc_link_deleting(lnk);
+		return 0;
+	}
+	return -ENOTCONN;
+}
+
 static void smc_lgr_free_work(struct work_struct *work)
 {
 	struct smc_link_group *lgr = container_of(to_delayed_work(work),
@@ -153,10 +173,21 @@ static void smc_lgr_free_work(struct work_struct *work)
 	list_del_init(&lgr->list); /* remove from smc_lgr_list */
 free:
 	spin_unlock_bh(&smc_lgr_list.lock);
+
+	if (!lgr->is_smcd && !lgr->terminating)	{
+		/* try to send del link msg, on error free lgr immediately */
+		if (!smc_link_send_delete(&lgr->lnk[SMC_SINGLE_LINK])) {
+			/* reschedule in case we never receive a response */
+			smc_lgr_schedule_free_work(lgr);
+			return;
+		}
+	}
+
 	if (!delayed_work_pending(&lgr->free_work)) {
-		if (!lgr->is_smcd &&
-		    lgr->lnk[SMC_SINGLE_LINK].state != SMC_LNK_INACTIVE)
-			smc_llc_link_inactive(&lgr->lnk[SMC_SINGLE_LINK]);
+		struct smc_link *lnk = &lgr->lnk[SMC_SINGLE_LINK];
+
+		if (!lgr->is_smcd && lnk->state != SMC_LNK_INACTIVE)
+			smc_llc_link_inactive(lnk);
 		smc_lgr_free(lgr);
 	}
 }
@@ -984,8 +1015,14 @@ void smc_core_exit(void)
 	spin_unlock_bh(&smc_lgr_list.lock);
 	list_for_each_entry_safe(lgr, lg, &lgr_freeing_list, list) {
 		list_del_init(&lgr->list);
-		if (!lgr->is_smcd)
-			smc_llc_link_inactive(&lgr->lnk[SMC_SINGLE_LINK]);
+		if (!lgr->is_smcd) {
+			struct smc_link *lnk = &lgr->lnk[SMC_SINGLE_LINK];
+
+			if (lnk->state == SMC_LNK_ACTIVE)
+				smc_llc_send_delete_link(lnk, SMC_LLC_REQ,
+							 false);
+			smc_llc_link_inactive(lnk);
+		}
 		cancel_delayed_work_sync(&lgr->free_work);
 		smc_lgr_free(lgr); /* free link group */
 	}

net/smc/smc_core.h

@@ -34,7 +34,8 @@ enum smc_lgr_role {		/* possible roles of a link group */
 enum smc_link_state {			/* possible states of a link */
 	SMC_LNK_INACTIVE,	/* link is inactive */
 	SMC_LNK_ACTIVATING,	/* link is being activated */
-	SMC_LNK_ACTIVE		/* link is active */
+	SMC_LNK_ACTIVE,		/* link is active */
+	SMC_LNK_DELETING,	/* link is being deleted */
 };
 
 #define SMC_WR_BUF_SIZE		48	/* size of work request buffer */
@@ -265,6 +266,7 @@ int smc_conn_create(struct smc_sock *smc, bool is_smcd, int srv_first_contact,
 		    struct smc_clc_msg_local *lcl, struct smcd_dev *smcd,
 		    u64 peer_gid);
 void smcd_conn_free(struct smc_connection *conn);
+void smc_lgr_schedule_free_work_fast(struct smc_link_group *lgr);
 void smc_core_exit(void);
 
 static inline struct smc_link_group *smc_get_lgr(struct smc_link *link)

net/smc/smc_llc.c

@@ -278,7 +278,7 @@ int smc_llc_send_add_link(struct smc_link *link, u8 mac[], u8 gid[],
 /* prepare a delete link message */
 static void smc_llc_prep_delete_link(struct smc_llc_msg_del_link *delllc,
 				     struct smc_link *link,
-				     enum smc_llc_reqresp reqresp)
+				     enum smc_llc_reqresp reqresp, bool orderly)
 {
 	memset(delllc, 0, sizeof(*delllc));
 	delllc->hd.common.type = SMC_LLC_DELETE_LINK;
@@ -287,13 +287,14 @@ static void smc_llc_prep_delete_link(struct smc_llc_msg_del_link *delllc,
 		delllc->hd.flags |= SMC_LLC_FLAG_RESP;
 	/* DEL_LINK_ALL because only 1 link supported */
 	delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ALL;
-	delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
+	if (orderly)
+		delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
 	delllc->link_num = link->link_id;
 }
 
 /* send DELETE LINK request or response */
 int smc_llc_send_delete_link(struct smc_link *link,
-			     enum smc_llc_reqresp reqresp)
+			     enum smc_llc_reqresp reqresp, bool orderly)
 {
 	struct smc_llc_msg_del_link *delllc;
 	struct smc_wr_tx_pend_priv *pend;
@@ -304,7 +305,7 @@ int smc_llc_send_delete_link(struct smc_link *link,
 	if (rc)
 		return rc;
 	delllc = (struct smc_llc_msg_del_link *)wr_buf;
-	smc_llc_prep_delete_link(delllc, link, reqresp);
+	smc_llc_prep_delete_link(delllc, link, reqresp, orderly);
 	/* send llc message */
 	rc = smc_wr_tx_send(link, pend);
 	return rc;
@@ -438,17 +439,19 @@ static void smc_llc_rx_delete_link(struct smc_link *link,
 
 	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
 		if (lgr->role == SMC_SERV)
-			smc_lgr_terminate(lgr);
+			smc_lgr_schedule_free_work_fast(lgr);
 	} else {
+		smc_lgr_forget(lgr);
+		smc_llc_link_deleting(link);
 		if (lgr->role == SMC_SERV) {
-			smc_lgr_forget(lgr);
-			smc_llc_prep_delete_link(llc, link, SMC_LLC_REQ);
-			smc_llc_send_message(link, llc, sizeof(*llc));
+			/* client asks to delete this link, send request */
+			smc_llc_prep_delete_link(llc, link, SMC_LLC_REQ, true);
 		} else {
-			smc_llc_prep_delete_link(llc, link, SMC_LLC_RESP);
-			smc_llc_send_message(link, llc, sizeof(*llc));
-			smc_lgr_terminate(lgr);
+			/* server requests to delete this link, send response */
+			smc_llc_prep_delete_link(llc, link, SMC_LLC_RESP, true);
 		}
+		smc_llc_send_message(link, llc, sizeof(*llc));
+		smc_lgr_schedule_free_work_fast(lgr);
 	}
 }
 
@@ -622,6 +625,11 @@ void smc_llc_link_active(struct smc_link *link, int testlink_time)
 	}
 }
 
+void smc_llc_link_deleting(struct smc_link *link)
+{
+	link->state = SMC_LNK_DELETING;
+}
+
 /* called in tasklet context */
 void smc_llc_link_inactive(struct smc_link *link)
 {

net/smc/smc_llc.h

@@ -41,9 +41,10 @@ int smc_llc_send_confirm_link(struct smc_link *lnk,
 int smc_llc_send_add_link(struct smc_link *link, u8 mac[], u8 gid[],
 			  enum smc_llc_reqresp reqresp);
 int smc_llc_send_delete_link(struct smc_link *link,
-			     enum smc_llc_reqresp reqresp);
+			     enum smc_llc_reqresp reqresp, bool orderly);
 int smc_llc_link_init(struct smc_link *link);
 void smc_llc_link_active(struct smc_link *link, int testlink_time);
+void smc_llc_link_deleting(struct smc_link *link);
 void smc_llc_link_inactive(struct smc_link *link);
 void smc_llc_link_clear(struct smc_link *link);
 int smc_llc_do_confirm_rkey(struct smc_link *link,

net/smc/smc_wr.c

@@ -182,17 +182,14 @@ int smc_wr_tx_get_free_slot(struct smc_link *link,
 		if (rc)
 			return rc;
 	} else {
-		struct smc_link_group *lgr;
-
-		lgr = smc_get_lgr(link);
 		rc = wait_event_timeout(
 			link->wr_tx_wait,
-			list_empty(&lgr->list) || /* lgr terminated */
+			link->state == SMC_LNK_INACTIVE ||
 			(smc_wr_tx_get_free_slot_index(link, &idx) != -EBUSY),
 			SMC_WR_TX_WAIT_FREE_SLOT_TIME);
 		if (!rc) {
 			/* timeout - terminate connections */
-			smc_lgr_terminate(lgr);
+			smc_lgr_terminate(smc_get_lgr(link));
 			return -EPIPE;
 		}
 		if (idx == link->wr_tx_cnt)