iscsi-target: Add login negotiation multi-plexing support

This patch adds support for login negotiation multi-plexing in
iscsi-target code.

This involves handling the first login request PDU + payload and
login response PDU + payload within __iscsi_target_login_thread()
process context, and then changing struct sock->sk_data_ready()
so that all subsequent exchanges are handled by workqueue process
context, to allow other incoming login requests to be received
in parallel by __iscsi_target_login_thread().

Upon login negotiation completion (or failure), ->sk_data_ready()
is replaced with the original kernel sockets handler saved in
iscsi_conn->orig_data_ready.

v3 changes:
  - Convert iscsi_target_sk_data_ready() lock access to
    write[lock,unlock]_bh()
  - Only clear LOGIN_FLAGS_READ_ACTIVE when iscsi_target_do_login()
    returns zero
  - Add LOGIN_FLAGS_READY + LOGIN_FLAGS_CLOSED bit checks to
    iscsi_target_sk_data_ready()
  - Make INIT_DELAYED_WORK() + iscsi_target_set_sock_callbacks() setup
    happen earlier by moving from iscsi_target_start_negotiation() into
    iscsi_target_locate_portal()
  - Set LOGIN_FLAGS_READY bit in iscsi_target_start_negotiation()
    after iscsi_target_do_login() returns zero.

v2 changes:
  - Add login_timer in iscsi_target_do_login_rx() to avoid
    possible endless sleep with MSG_WAITALL for traditional
    iscsi-target in certain network configurations.
  - Convert lprintk() -> pr_debug()
  - Remove forward declarations of iscsi_target_set_sock_callbacks(),
    iscsi_target_restore_sock_callbacks() and iscsi_target_sk_data_ready()
  - Make iscsi_target_set_sock_callbacks + iscsi_target_restore_sock_callbacks()
    static (Fengguang)
  - Make iscsi_target_do_login_rx() safe for iser-target w/o conn->sock

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

4 files changed, 234 insertions, 10 deletions

diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index 46228465d190..43228dc786c9 100644
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -564,6 +564,7 @@ struct iscsi_conn {
         struct timer_list       nopin_timer;
         struct timer_list       nopin_response_timer;
         struct timer_list       transport_timer;
+        struct task_struct      *login_kworker;
         /* Spinlock used for add/deleting cmd's from conn_cmd_list */
         spinlock_t              cmd_lock;
         spinlock_t              conn_usage_lock;
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index c4675b4ceb49..9defee0f0aeb 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -377,14 +377,207 @@ static int iscsi_target_do_tx_login_io(struct iscsi_conn *conn, struct iscsi_log
         return 0;
 }
 
+static void iscsi_target_sk_data_ready(struct sock *sk, int count)
+{
+        struct iscsi_conn *conn = sk->sk_user_data;
+        bool rc;
+
+        pr_debug("Entering iscsi_target_sk_data_ready: conn: %p\n", conn);
+
+        write_lock_bh(&sk->sk_callback_lock);
+        if (!sk->sk_user_data) {
+                write_unlock_bh(&sk->sk_callback_lock);
+                return;
+        }
+        if (!test_bit(LOGIN_FLAGS_READY, &conn->login_flags)) {
+                write_unlock_bh(&sk->sk_callback_lock);
+                pr_debug("Got LOGIN_FLAGS_READY=0, conn: %p >>>>\n", conn);
+                return;
+        }
+        if (test_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags)) {
+                write_unlock_bh(&sk->sk_callback_lock);
+                pr_debug("Got LOGIN_FLAGS_CLOSED=1, conn: %p >>>>\n", conn);
+                return;
+        }
+        if (test_and_set_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags)) {
+                write_unlock_bh(&sk->sk_callback_lock);
+                pr_debug("Got LOGIN_FLAGS_READ_ACTIVE=1, conn: %p >>>>\n", conn);
+                return;
+        }
+
+        rc = schedule_delayed_work(&conn->login_work, 0);
+        if (rc == false) {
+                pr_debug("iscsi_target_sk_data_ready, schedule_delayed_work"
+                         " got false\n");
+        }
+        write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void iscsi_target_set_sock_callbacks(struct iscsi_conn *conn)
+{
+        struct sock *sk;
+
+        if (!conn->sock)
+                return;
+
+        sk = conn->sock->sk;
+        pr_debug("Entering iscsi_target_set_sock_callbacks: conn: %p\n", conn);
+
+        write_lock_bh(&sk->sk_callback_lock);
+        sk->sk_user_data = conn;
+        conn->orig_data_ready = sk->sk_data_ready;
+        sk->sk_data_ready = iscsi_target_sk_data_ready;
+        write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void iscsi_target_restore_sock_callbacks(struct iscsi_conn *conn)
+{
+        struct sock *sk;
+
+        if (!conn->sock)
+                return;
+
+        sk = conn->sock->sk;
+        pr_debug("Entering iscsi_target_restore_sock_callbacks: conn: %p\n", conn);
+
+        write_lock_bh(&sk->sk_callback_lock);
+        if (!sk->sk_user_data) {
+                write_unlock_bh(&sk->sk_callback_lock);
+                return;
+        }
+        sk->sk_user_data = NULL;
+        sk->sk_data_ready = conn->orig_data_ready;
+        write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static int iscsi_target_do_login(struct iscsi_conn *, struct iscsi_login *);
+
+static bool iscsi_target_sk_state_check(struct sock *sk)
+{
+        if (sk->sk_state == TCP_CLOSE_WAIT || sk->sk_state == TCP_CLOSE) {
+                pr_debug("iscsi_target_sk_state_check: TCP_CLOSE_WAIT|TCP_CLOSE,"
+                        "returning FALSE\n");
+                return false;
+        }
+        return true;
+}
+
+static void iscsi_target_login_drop(struct iscsi_conn *conn, struct iscsi_login *login)
+{
+        struct iscsi_np *np = login->np;
+        bool zero_tsih = login->zero_tsih;
+
+        iscsi_remove_failed_auth_entry(conn);
+        iscsi_target_nego_release(conn);
+        iscsi_target_login_sess_out(conn, np, zero_tsih, true);
+}
+
+static void iscsi_target_login_timeout(unsigned long data)
+{
+        struct iscsi_conn *conn = (struct iscsi_conn *)data;
+
+        pr_debug("Entering iscsi_target_login_timeout >>>>>>>>>>>>>>>>>>>\n");
+
+        if (conn->login_kworker) {
+                pr_debug("Sending SIGINT to conn->login_kworker %s/%d\n",
+                         conn->login_kworker->comm, conn->login_kworker->pid);
+                send_sig(SIGINT, conn->login_kworker, 1);
+        }
+}
+
+static void iscsi_target_do_login_rx(struct work_struct *work)
+{
+        struct iscsi_conn *conn = container_of(work,
+                                struct iscsi_conn, login_work.work);
+        struct iscsi_login *login = conn->login;
+        struct iscsi_np *np = login->np;
+        struct iscsi_portal_group *tpg = conn->tpg;
+        struct iscsi_tpg_np *tpg_np = conn->tpg_np;
+        struct timer_list login_timer;
+        int rc, zero_tsih = login->zero_tsih;
+        bool state;
+
+        pr_debug("entering iscsi_target_do_login_rx, conn: %p, %s:%d\n",
+                        conn, current->comm, current->pid);
+
+        spin_lock(&tpg->tpg_state_lock);
+        state = (tpg->tpg_state == TPG_STATE_ACTIVE);
+        spin_unlock(&tpg->tpg_state_lock);
+
+        if (state == false) {
+                pr_debug("iscsi_target_do_login_rx: tpg_state != TPG_STATE_ACTIVE\n");
+                iscsi_target_restore_sock_callbacks(conn);
+                iscsi_target_login_drop(conn, login);
+                iscsit_deaccess_np(np, tpg, tpg_np);
+                return;
+        }
+
+        if (conn->sock) {
+                struct sock *sk = conn->sock->sk;
+
+                read_lock_bh(&sk->sk_callback_lock);
+                state = iscsi_target_sk_state_check(sk);
+                read_unlock_bh(&sk->sk_callback_lock);
+
+                if (state == false) {
+                        pr_debug("iscsi_target_do_login_rx, TCP state CLOSE\n");
+                        iscsi_target_restore_sock_callbacks(conn);
+                        iscsi_target_login_drop(conn, login);
+                        iscsit_deaccess_np(np, tpg, tpg_np);
+                        return;
+                }
+        }
+
+        conn->login_kworker = current;
+        allow_signal(SIGINT);
+
+        init_timer(&login_timer);
+        login_timer.expires = (get_jiffies_64() + TA_LOGIN_TIMEOUT * HZ);
+        login_timer.data = (unsigned long)conn;
+        login_timer.function = iscsi_target_login_timeout;
+        add_timer(&login_timer);
+        pr_debug("Starting login_timer for %s/%d\n", current->comm, current->pid);
+
+        rc = conn->conn_transport->iscsit_get_login_rx(conn, login);
+        del_timer_sync(&login_timer);
+        flush_signals(current);
+        conn->login_kworker = NULL;
+
+        if (rc < 0) {
+                iscsi_target_restore_sock_callbacks(conn);
+                iscsi_target_login_drop(conn, login);
+                iscsit_deaccess_np(np, tpg, tpg_np);
+                return;
+        }
+
+        pr_debug("iscsi_target_do_login_rx after rx_login_io, %p, %s:%d\n",
+                        conn, current->comm, current->pid);
+
+        rc = iscsi_target_do_login(conn, login);
+        if (rc < 0) {
+                iscsi_target_restore_sock_callbacks(conn);
+                iscsi_target_login_drop(conn, login);
+                iscsit_deaccess_np(np, tpg, tpg_np);
+        } else if (!rc) {
+                if (conn->sock) {
+                        struct sock *sk = conn->sock->sk;
+
+                        write_lock_bh(&sk->sk_callback_lock);
+                        clear_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags);
+                        write_unlock_bh(&sk->sk_callback_lock);
+                }
+        } else if (rc == 1) {
+                iscsi_target_nego_release(conn);
+                iscsi_post_login_handler(np, conn, zero_tsih);
+                iscsit_deaccess_np(np, tpg, tpg_np);
+        }
+}
+
 static int iscsi_target_do_login_io(struct iscsi_conn *conn, struct iscsi_login *login)
 {
         if (iscsi_target_do_tx_login_io(conn, login) < 0)
                 return -1;
 
-        if (conn->conn_transport->iscsit_get_login_rx(conn, login) < 0)
-                return -1;
-
         return 0;
 }
 
@@ -643,10 +836,11 @@ static int iscsi_target_do_login(struct iscsi_conn *conn, struct iscsi_login *lo
                         if (login_rsp->flags & ISCSI_FLAG_LOGIN_TRANSIT) {
                                 login->tsih = conn->sess->tsih;
                                 login->login_complete = 1;
+                                iscsi_target_restore_sock_callbacks(conn);
                                 if (iscsi_target_do_tx_login_io(conn,
                                                 login) < 0)
                                         return -1;
-                                return 0;
+                                return 1;
                         }
                         break;
                 default:
@@ -663,6 +857,7 @@ static int iscsi_target_do_login(struct iscsi_conn *conn, struct iscsi_login *lo
                         login_rsp->flags &= ~ISCSI_FLAG_LOGIN_TRANSIT;
                         login_rsp->flags &= ~ISCSI_FLAG_LOGIN_NEXT_STAGE_MASK;
                 }
+                break;
         }
 
         return 0;
@@ -695,10 +890,16 @@ int iscsi_target_locate_portal(
         char *tmpbuf, *start = NULL, *end = NULL, *key, *value;
         struct iscsi_session *sess = conn->sess;
         struct iscsi_tiqn *tiqn;
+        struct iscsi_tpg_np *tpg_np = NULL;
         struct iscsi_login_req *login_req;
         u32 payload_length;
         int sessiontype = 0, ret = 0;
 
+        INIT_DELAYED_WORK(&conn->login_work, iscsi_target_do_login_rx);
+        iscsi_target_set_sock_callbacks(conn);
+
+        login->np = np;
+
         login_req = (struct iscsi_login_req *) login->req;
         payload_length = ntoh24(login_req->dlength);
 
@@ -822,7 +1023,7 @@ get_target:
         /*
          * Locate Target Portal Group from Storage Node.
          */
-        conn->tpg = iscsit_get_tpg_from_np(tiqn, np);
+        conn->tpg = iscsit_get_tpg_from_np(tiqn, np, &tpg_np);
         if (!conn->tpg) {
                 pr_err("Unable to locate Target Portal Group"
                                 " on %s\n", tiqn->tiqn);
@@ -832,12 +1033,16 @@ get_target:
                 ret = -1;
                 goto out;
         }
+        conn->tpg_np = tpg_np;
         pr_debug("Located Portal Group Object: %hu\n", conn->tpg->tpgt);
         /*
          * Setup crc32c modules from libcrypto
          */
         if (iscsi_login_setup_crypto(conn) < 0) {
                 pr_err("iscsi_login_setup_crypto() failed\n");
+                kref_put(&tpg_np->tpg_np_kref, iscsit_login_kref_put);
+                iscsit_put_tiqn_for_login(tiqn);
+                conn->tpg = NULL;
                 ret = -1;
                 goto out;
         }
@@ -846,11 +1051,12 @@ get_target:
          * process login attempt.
          */
         if (iscsit_access_np(np, conn->tpg) < 0) {
+                kref_put(&tpg_np->tpg_np_kref, iscsit_login_kref_put);
                 iscsit_put_tiqn_for_login(tiqn);
                 iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_TARGET_ERR,
                                 ISCSI_LOGIN_STATUS_SVC_UNAVAILABLE);
-                ret = -1;
                 conn->tpg = NULL;
+                ret = -1;
                 goto out;
         }
 
@@ -897,10 +1103,22 @@ int iscsi_target_start_negotiation(
         int ret;
 
         ret = iscsi_target_do_login(conn, login);
-        if (ret != 0)
+        if (!ret) {
+                if (conn->sock) {
+                        struct sock *sk = conn->sock->sk;
+
+                        write_lock_bh(&sk->sk_callback_lock);
+                        set_bit(LOGIN_FLAGS_READY, &conn->login_flags);
+                        write_unlock_bh(&sk->sk_callback_lock);
+                }
+        } else if (ret < 0) {
+                cancel_delayed_work_sync(&conn->login_work);
+                iscsi_target_restore_sock_callbacks(conn);
                 iscsi_remove_failed_auth_entry(conn);
+        }
+        if (ret != 0)
+                iscsi_target_nego_release(conn);
 
-        iscsi_target_nego_release(conn);
         return ret;
 }
 
diff --git a/drivers/target/iscsi/iscsi_target_tpg.c b/drivers/target/iscsi/iscsi_target_tpg.c
index 4bf8913992a5..e070ce2de60a 100644
--- a/drivers/target/iscsi/iscsi_target_tpg.c
+++ b/drivers/target/iscsi/iscsi_target_tpg.c
@@ -129,7 +129,8 @@ void iscsit_release_discovery_tpg(void)
 
 struct iscsi_portal_group *iscsit_get_tpg_from_np(
         struct iscsi_tiqn *tiqn,
-        struct iscsi_np *np)
+        struct iscsi_np *np,
+        struct iscsi_tpg_np **tpg_np_out)
 {
         struct iscsi_portal_group *tpg = NULL;
         struct iscsi_tpg_np *tpg_np;
@@ -147,6 +148,8 @@ struct iscsi_portal_group *iscsit_get_tpg_from_np(
                 spin_lock(&tpg->tpg_np_lock);
                 list_for_each_entry(tpg_np, &tpg->tpg_gnp_list, tpg_np_list) {
                         if (tpg_np->tpg_np == np) {
+                                *tpg_np_out = tpg_np;
+                                kref_get(&tpg_np->tpg_np_kref);
                                 spin_unlock(&tpg->tpg_np_lock);
                                 spin_unlock(&tiqn->tiqn_tpg_lock);
                                 return tpg;
@@ -494,6 +497,8 @@ struct iscsi_tpg_np *iscsit_tpg_add_network_portal(
         INIT_LIST_HEAD(&tpg_np->tpg_np_child_list);
         INIT_LIST_HEAD(&tpg_np->tpg_np_parent_list);
         spin_lock_init(&tpg_np->tpg_np_parent_lock);
+        init_completion(&tpg_np->tpg_np_comp);
+        kref_init(&tpg_np->tpg_np_kref);
         tpg_np->tpg_np          = np;
         tpg_np->tpg             = tpg;
 
diff --git a/drivers/target/iscsi/iscsi_target_tpg.h b/drivers/target/iscsi/iscsi_target_tpg.h
index 60ef4a9ad91b..b77693e2c209 100644
--- a/drivers/target/iscsi/iscsi_target_tpg.h
+++ b/drivers/target/iscsi/iscsi_target_tpg.h
@@ -5,7 +5,7 @@ extern struct iscsi_portal_group *iscsit_alloc_portal_group(struct iscsi_tiqn *,
 extern int iscsit_load_discovery_tpg(void);
 extern void iscsit_release_discovery_tpg(void);
 extern struct iscsi_portal_group *iscsit_get_tpg_from_np(struct iscsi_tiqn *,
-                        struct iscsi_np *);
+                        struct iscsi_np *, struct iscsi_tpg_np **);
 extern int iscsit_get_tpg(struct iscsi_portal_group *);
 extern void iscsit_put_tpg(struct iscsi_portal_group *);
 extern void iscsit_clear_tpg_np_login_threads(struct iscsi_portal_group *, bool);