iscsi-target: Convert iscsi_thread_set usage to kthread.h

This patch converts iscsi-target code to use modern kthread.h API
callers for creating RX/TX threads for each new iscsi_conn descriptor,
and releasing associated RX/TX threads during connection shutdown.

This is done using iscsit_start_kthreads() -> kthread_run() to start
new kthreads from within iscsi_post_login_handler(), and invoking
kthread_stop() from existing iscsit_close_connection() code.

Also, convert iscsit_logout_post_handler_closesession() code to use
cmpxchg when determing when iscsit_cause_connection_reinstatement()
needs to sleep waiting for completion.

Reported-by: Sagi Grimberg <sagig@mellanox.com>
Tested-by: Sagi Grimberg <sagig@mellanox.com>
Cc: Slava Shwartsman <valyushash@gmail.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 54 insertions, 5 deletions

diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 153fb66ac1b8..345f073ff6dc 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -699,6 +699,51 @@ static void iscsi_post_login_start_timers(struct iscsi_conn *conn)
 		iscsit_start_nopin_timer(conn);
 }
 
+int iscsit_start_kthreads(struct iscsi_conn *conn)
+{
+	int ret = 0;
+
+	spin_lock(&iscsit_global->ts_bitmap_lock);
+	conn->bitmap_id = bitmap_find_free_region(iscsit_global->ts_bitmap,
+					ISCSIT_BITMAP_BITS, get_order(1));
+	spin_unlock(&iscsit_global->ts_bitmap_lock);
+
+	if (conn->bitmap_id < 0) {
+		pr_err("bitmap_find_free_region() failed for"
+		       " iscsit_start_kthreads()\n");
+		return -ENOMEM;
+	}
+
+	conn->tx_thread = kthread_run(iscsi_target_tx_thread, conn,
+				      "%s", ISCSI_TX_THREAD_NAME);
+	if (IS_ERR(conn->tx_thread)) {
+		pr_err("Unable to start iscsi_target_tx_thread\n");
+		ret = PTR_ERR(conn->tx_thread);
+		goto out_bitmap;
+	}
+	conn->tx_thread_active = true;
+
+	conn->rx_thread = kthread_run(iscsi_target_rx_thread, conn,
+				      "%s", ISCSI_RX_THREAD_NAME);
+	if (IS_ERR(conn->rx_thread)) {
+		pr_err("Unable to start iscsi_target_rx_thread\n");
+		ret = PTR_ERR(conn->rx_thread);
+		goto out_tx;
+	}
+	conn->rx_thread_active = true;
+
+	return 0;
+out_tx:
+	kthread_stop(conn->tx_thread);
+	conn->tx_thread_active = false;
+out_bitmap:
+	spin_lock(&iscsit_global->ts_bitmap_lock);
+	bitmap_release_region(iscsit_global->ts_bitmap, conn->bitmap_id,
+			      get_order(1));
+	spin_unlock(&iscsit_global->ts_bitmap_lock);
+	return ret;
+}
+
 int iscsi_post_login_handler(
 	struct iscsi_np *np,
 	struct iscsi_conn *conn,
@@ -709,7 +754,7 @@ int iscsi_post_login_handler(
 	struct se_session *se_sess = sess->se_sess;
 	struct iscsi_portal_group *tpg = sess->tpg;
 	struct se_portal_group *se_tpg = &tpg->tpg_se_tpg;
-	struct iscsi_thread_set *ts;
+	int rc;
 
 	iscsit_inc_conn_usage_count(conn);
 
@@ -724,7 +769,6 @@ int iscsi_post_login_handler(
 	/*
 	 * SCSI Initiator -> SCSI Target Port Mapping
 	 */
-	ts = iscsi_get_thread_set();
 	if (!zero_tsih) {
 		iscsi_set_session_parameters(sess->sess_ops,
 				conn->param_list, 0);
@@ -751,9 +795,11 @@ int iscsi_post_login_handler(
 			sess->sess_ops->InitiatorName);
 		spin_unlock_bh(&sess->conn_lock);
 
-		iscsi_post_login_start_timers(conn);
+		rc = iscsit_start_kthreads(conn);
+		if (rc)
+			return rc;
 
-		iscsi_activate_thread_set(conn, ts);
+		iscsi_post_login_start_timers(conn);
 		/*
 		 * Determine CPU mask to ensure connection's RX and TX kthreads
 		 * are scheduled on the same CPU.
@@ -810,8 +856,11 @@ int iscsi_post_login_handler(
 		" iSCSI Target Portal Group: %hu\n", tpg->nsessions, tpg->tpgt);
 	spin_unlock_bh(&se_tpg->session_lock);
 
+	rc = iscsit_start_kthreads(conn);
+	if (rc)
+		return rc;
+
 	iscsi_post_login_start_timers(conn);
-	iscsi_activate_thread_set(conn, ts);
 	/*
 	 * Determine CPU mask to ensure connection's RX and TX kthreads
 	 * are scheduled on the same CPU.