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, 45 insertions, 59 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 47af861..163773f 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -537,7 +537,7 @@ static struct iscsit_transport iscsi_target_transport = {
 
 static int __init iscsi_target_init_module(void)
 {
-	int ret = 0;
+	int ret = 0, size;
 
 	pr_debug("iSCSI-Target "ISCSIT_VERSION"\n");
 
@@ -546,6 +546,7 @@ static int __init iscsi_target_init_module(void)
 		pr_err("Unable to allocate memory for iscsit_global\n");
 		return -1;
 	}
+	spin_lock_init(&iscsit_global->ts_bitmap_lock);
 	mutex_init(&auth_id_lock);
 	spin_lock_init(&sess_idr_lock);
 	idr_init(&tiqn_idr);
@@ -555,15 +556,11 @@ static int __init iscsi_target_init_module(void)
 	if (ret < 0)
 		goto out;
 
-	ret = iscsi_thread_set_init();
-	if (ret < 0)
+	size = BITS_TO_LONGS(ISCSIT_BITMAP_BITS) * sizeof(long);
+	iscsit_global->ts_bitmap = vzalloc(size);
+	if (!iscsit_global->ts_bitmap) {
+		pr_err("Unable to allocate iscsit_global->ts_bitmap\n");
 		goto configfs_out;
-
-	if (iscsi_allocate_thread_sets(TARGET_THREAD_SET_COUNT) !=
-			TARGET_THREAD_SET_COUNT) {
-		pr_err("iscsi_allocate_thread_sets() returned"
-			" unexpected value!\n");
-		goto ts_out1;
 	}
 
 	lio_qr_cache = kmem_cache_create("lio_qr_cache",
@@ -572,7 +569,7 @@ static int __init iscsi_target_init_module(void)
 	if (!lio_qr_cache) {
 		pr_err("nable to kmem_cache_create() for"
 				" lio_qr_cache\n");
-		goto ts_out2;
+		goto bitmap_out;
 	}
 
 	lio_dr_cache = kmem_cache_create("lio_dr_cache",
@@ -617,10 +614,8 @@ dr_out:
 	kmem_cache_destroy(lio_dr_cache);
 qr_out:
 	kmem_cache_destroy(lio_qr_cache);
-ts_out2:
-	iscsi_deallocate_thread_sets();
-ts_out1:
-	iscsi_thread_set_free();
+bitmap_out:
+	vfree(iscsit_global->ts_bitmap);
 configfs_out:
 	iscsi_target_deregister_configfs();
 out:
@@ -630,8 +625,6 @@ out:
 
 static void __exit iscsi_target_cleanup_module(void)
 {
-	iscsi_deallocate_thread_sets();
-	iscsi_thread_set_free();
 	iscsit_release_discovery_tpg();
 	iscsit_unregister_transport(&iscsi_target_transport);
 	kmem_cache_destroy(lio_qr_cache);
@@ -641,6 +634,7 @@ static void __exit iscsi_target_cleanup_module(void)
 
 	iscsi_target_deregister_configfs();
 
+	vfree(iscsit_global->ts_bitmap);
 	kfree(iscsit_global);
 }
 
@@ -3709,17 +3703,16 @@ static int iscsit_send_reject(
 
 void iscsit_thread_get_cpumask(struct iscsi_conn *conn)
 {
-	struct iscsi_thread_set *ts = conn->thread_set;
 	int ord, cpu;
 	/*
-	 * thread_id is assigned from iscsit_global->ts_bitmap from
-	 * within iscsi_thread_set.c:iscsi_allocate_thread_sets()
+	 * bitmap_id is assigned from iscsit_global->ts_bitmap from
+	 * within iscsit_start_kthreads()
 	 *
-	 * Here we use thread_id to determine which CPU that this
-	 * iSCSI connection's iscsi_thread_set will be scheduled to
+	 * Here we use bitmap_id to determine which CPU that this
+	 * iSCSI connection's RX/TX threads will be scheduled to
 	 * execute upon.
 	 */
-	ord = ts->thread_id % cpumask_weight(cpu_online_mask);
+	ord = conn->bitmap_id % cpumask_weight(cpu_online_mask);
 	for_each_online_cpu(cpu) {
 		if (ord-- == 0) {
 			cpumask_set_cpu(cpu, conn->conn_cpumask);
@@ -3908,7 +3901,7 @@ check_rsp_state:
 	switch (state) {
 	case ISTATE_SEND_LOGOUTRSP:
 		if (!iscsit_logout_post_handler(cmd, conn))
-			goto restart;
+			return -ECONNRESET;
 		/* fall through */
 	case ISTATE_SEND_STATUS:
 	case ISTATE_SEND_ASYNCMSG:
@@ -3936,8 +3929,6 @@ check_rsp_state:
 
 err:
 	return -1;
-restart:
-	return -EAGAIN;
 }
 
 static int iscsit_handle_response_queue(struct iscsi_conn *conn)
@@ -3964,21 +3955,13 @@ static int iscsit_handle_response_queue(struct iscsi_conn *conn)
 int iscsi_target_tx_thread(void *arg)
 {
 	int ret = 0;
-	struct iscsi_conn *conn;
-	struct iscsi_thread_set *ts = arg;
+	struct iscsi_conn *conn = arg;
 	/*
 	 * Allow ourselves to be interrupted by SIGINT so that a
 	 * connection recovery / failure event can be triggered externally.
 	 */
 	allow_signal(SIGINT);
 
-restart:
-	conn = iscsi_tx_thread_pre_handler(ts);
-	if (!conn)
-		goto out;
-
-	ret = 0;
-
 	while (!kthread_should_stop()) {
 		/*
 		 * Ensure that both TX and RX per connection kthreads
@@ -3987,11 +3970,9 @@ restart:
 		iscsit_thread_check_cpumask(conn, current, 1);
 
 		wait_event_interruptible(conn->queues_wq,
-					 !iscsit_conn_all_queues_empty(conn) ||
-					 ts->status == ISCSI_THREAD_SET_RESET);
+					 !iscsit_conn_all_queues_empty(conn));
 
-		if ((ts->status == ISCSI_THREAD_SET_RESET) ||
-		     signal_pending(current))
+		if (signal_pending(current))
 			goto transport_err;
 
 get_immediate:
@@ -4002,15 +3983,14 @@ get_immediate:
 		ret = iscsit_handle_response_queue(conn);
 		if (ret == 1)
 			goto get_immediate;
-		else if (ret == -EAGAIN)
-			goto restart;
+		else if (ret == -ECONNRESET)
+			goto out;
 		else if (ret < 0)
 			goto transport_err;
 	}
 
 transport_err:
 	iscsit_take_action_for_connection_exit(conn);
-	goto restart;
 out:
 	return 0;
 }
@@ -4105,8 +4085,7 @@ int iscsi_target_rx_thread(void *arg)
 	int ret;
 	u8 buffer[ISCSI_HDR_LEN], opcode;
 	u32 checksum = 0, digest = 0;
-	struct iscsi_conn *conn = NULL;
-	struct iscsi_thread_set *ts = arg;
+	struct iscsi_conn *conn = arg;
 	struct kvec iov;
 	/*
 	 * Allow ourselves to be interrupted by SIGINT so that a
@@ -4114,11 +4093,6 @@ int iscsi_target_rx_thread(void *arg)
 	 */
 	allow_signal(SIGINT);
 
-restart:
-	conn = iscsi_rx_thread_pre_handler(ts);
-	if (!conn)
-		goto out;
-
 	if (conn->conn_transport->transport_type == ISCSI_INFINIBAND) {
 		struct completion comp;
 		int rc;
@@ -4128,7 +4102,7 @@ restart:
 		if (rc < 0)
 			goto transport_err;
 
-		goto out;
+		goto transport_err;
 	}
 
 	while (!kthread_should_stop()) {
@@ -4204,8 +4178,6 @@ transport_err:
 	if (!signal_pending(current))
 		atomic_set(&conn->transport_failed, 1);
 	iscsit_take_action_for_connection_exit(conn);
-	goto restart;
-out:
 	return 0;
 }
 
@@ -4261,7 +4233,24 @@ int iscsit_close_connection(
 	 */
 	complete(&conn->conn_logout_comp);
 
-	iscsi_release_thread_set(conn);
+	if (!strcmp(current->comm, ISCSI_RX_THREAD_NAME)) {
+		if (conn->tx_thread &&
+		    cmpxchg(&conn->tx_thread_active, true, false)) {
+			send_sig(SIGINT, conn->tx_thread, 1);
+			kthread_stop(conn->tx_thread);
+		}
+	} else if (!strcmp(current->comm, ISCSI_TX_THREAD_NAME)) {
+		if (conn->rx_thread &&
+		    cmpxchg(&conn->rx_thread_active, true, false)) {
+			send_sig(SIGINT, conn->rx_thread, 1);
+			kthread_stop(conn->rx_thread);
+		}
+	}
+
+	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);
 
 	iscsit_stop_timers_for_cmds(conn);
 	iscsit_stop_nopin_response_timer(conn);
@@ -4539,15 +4528,13 @@ static void iscsit_logout_post_handler_closesession(
 	struct iscsi_conn *conn)
 {
 	struct iscsi_session *sess = conn->sess;
-
-	iscsi_set_thread_clear(conn, ISCSI_CLEAR_TX_THREAD);
-	iscsi_set_thread_set_signal(conn, ISCSI_SIGNAL_TX_THREAD);
+	int sleep = cmpxchg(&conn->tx_thread_active, true, false);
 
 	atomic_set(&conn->conn_logout_remove, 0);
 	complete(&conn->conn_logout_comp);
 
 	iscsit_dec_conn_usage_count(conn);
-	iscsit_stop_session(sess, 1, 1);
+	iscsit_stop_session(sess, sleep, sleep);
 	iscsit_dec_session_usage_count(sess);
 	target_put_session(sess->se_sess);
 }
@@ -4555,13 +4542,12 @@ static void iscsit_logout_post_handler_closesession(
 static void iscsit_logout_post_handler_samecid(
 	struct iscsi_conn *conn)
 {
-	iscsi_set_thread_clear(conn, ISCSI_CLEAR_TX_THREAD);
-	iscsi_set_thread_set_signal(conn, ISCSI_SIGNAL_TX_THREAD);
+	int sleep = cmpxchg(&conn->tx_thread_active, true, false);
 
 	atomic_set(&conn->conn_logout_remove, 0);
 	complete(&conn->conn_logout_comp);
 
-	iscsit_cause_connection_reinstatement(conn, 1);
+	iscsit_cause_connection_reinstatement(conn, sleep);
 	iscsit_dec_conn_usage_count(conn);
 }