iscsi-target: Add sk->sk_state_change to cleanup after TCP failure

This patch adds a sock->sk_state_change() -> iscsi_target_sk_state_change()
callback in order to handle transient TCP failures during the login process,
where sock->sk_data_ready() -> iscsi_target_sk_data_ready() may not be
called to release connection resources, and relinquish tpg->np_login_lock
via iscsit_deaccess_np()

It performs the sk->sk_state check using iscsi_target_sk_state_check() to
look for TCP_CLOSE_WAIT + TCP_CLOSE, and invokes schedule_delayed_work() ->
iscsi_target_do_cleanup() to perform the remaining cleanup from process
context.

It adds an explicit sk_state_check to iscsi_target_do_login() in order
to determine a state failure when iscsi_target_sk_state_change() may
not be able to proceed before LOGIN_FLAGS_READY=1 is set.

Also use sk->sk_sndtimeo -> sk->sk_rcvtimeo settings during login to
iscsi_target_set_sock_callbacks(), and revert back post login to use
MAX_SCHEDULE_TIMEOUT in iscsi_target_restore_sock_callbacks().

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

2 files changed, 103 insertions, 0 deletions

diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index 43228dc786c9..089a0e915da8 100644
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -555,11 +555,13 @@ struct iscsi_conn {
         /* socket used by this connection */
         struct socket           *sock;
         void                    (*orig_data_ready)(struct sock *, int);
+        void                    (*orig_state_change)(struct sock *);
 #define LOGIN_FLAGS_READ_ACTIVE         1
 #define LOGIN_FLAGS_CLOSED              2
 #define LOGIN_FLAGS_READY               4
         unsigned long           login_flags;
         struct delayed_work     login_work;
+        struct delayed_work     login_cleanup_work;
         struct iscsi_login      *login;
         struct timer_list       nopin_timer;
         struct timer_list       nopin_response_timer;
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 9defee0f0aeb..9d0c910e41f9 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -413,6 +413,8 @@ static void iscsi_target_sk_data_ready(struct sock *sk, int count)
         write_unlock_bh(&sk->sk_callback_lock);
 }
 
+static void iscsi_target_sk_state_change(struct sock *);
+
 static void iscsi_target_set_sock_callbacks(struct iscsi_conn *conn)
 {
         struct sock *sk;
@@ -426,8 +428,13 @@ static void iscsi_target_set_sock_callbacks(struct iscsi_conn *conn)
         write_lock_bh(&sk->sk_callback_lock);
         sk->sk_user_data = conn;
         conn->orig_data_ready = sk->sk_data_ready;
+        conn->orig_state_change = sk->sk_state_change;
         sk->sk_data_ready = iscsi_target_sk_data_ready;
+        sk->sk_state_change = iscsi_target_sk_state_change;
         write_unlock_bh(&sk->sk_callback_lock);
+
+        sk->sk_sndtimeo = TA_LOGIN_TIMEOUT * HZ;
+        sk->sk_rcvtimeo = TA_LOGIN_TIMEOUT * HZ;
 }
 
 static void iscsi_target_restore_sock_callbacks(struct iscsi_conn *conn)
@@ -447,7 +454,11 @@ static void iscsi_target_restore_sock_callbacks(struct iscsi_conn *conn)
         }
         sk->sk_user_data = NULL;
         sk->sk_data_ready = conn->orig_data_ready;
+        sk->sk_state_change = conn->orig_state_change;
         write_unlock_bh(&sk->sk_callback_lock);
+
+        sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
+        sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;
 }
 
 static int iscsi_target_do_login(struct iscsi_conn *, struct iscsi_login *);
@@ -573,6 +584,79 @@ static void iscsi_target_do_login_rx(struct work_struct *work)
         }
 }
 
+static void iscsi_target_do_cleanup(struct work_struct *work)
+{
+        struct iscsi_conn *conn = container_of(work,
+                                struct iscsi_conn, login_cleanup_work.work);
+        struct sock *sk = conn->sock->sk;
+        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;
+
+        pr_debug("Entering iscsi_target_do_cleanup\n");
+
+        cancel_delayed_work_sync(&conn->login_work);
+        conn->orig_state_change(sk);
+
+        iscsi_target_restore_sock_callbacks(conn);
+        iscsi_target_login_drop(conn, login);
+        iscsit_deaccess_np(np, tpg, tpg_np);
+
+        pr_debug("iscsi_target_do_cleanup done()\n");
+}
+
+static void iscsi_target_sk_state_change(struct sock *sk)
+{
+        struct iscsi_conn *conn;
+        void (*orig_state_change)(struct sock *);
+        bool state;
+
+        pr_debug("Entering iscsi_target_sk_state_change\n");
+
+        write_lock_bh(&sk->sk_callback_lock);
+        conn = sk->sk_user_data;
+        if (!conn) {
+                write_unlock_bh(&sk->sk_callback_lock);
+                return;
+        }
+        orig_state_change = conn->orig_state_change;
+
+        if (!test_bit(LOGIN_FLAGS_READY, &conn->login_flags)) {
+                pr_debug("Got LOGIN_FLAGS_READY=0 sk_state_change conn: %p\n",
+                         conn);
+                write_unlock_bh(&sk->sk_callback_lock);
+                orig_state_change(sk);
+                return;
+        }
+        if (test_bit(LOGIN_FLAGS_READ_ACTIVE, &conn->login_flags)) {
+                pr_debug("Got LOGIN_FLAGS_READ_ACTIVE=1 sk_state_change"
+                         " conn: %p\n", conn);
+                write_unlock_bh(&sk->sk_callback_lock);
+                orig_state_change(sk);
+                return;
+        }
+        if (test_and_set_bit(LOGIN_FLAGS_CLOSED, &conn->login_flags)) {
+                pr_debug("Got LOGIN_FLAGS_CLOSED=1 sk_state_change conn: %p\n",
+                         conn);
+                write_unlock_bh(&sk->sk_callback_lock);
+                orig_state_change(sk);
+                return;
+        }
+
+        state = iscsi_target_sk_state_check(sk);
+        write_unlock_bh(&sk->sk_callback_lock);
+
+        pr_debug("iscsi_target_sk_state_change: state: %d\n", state);
+
+        if (!state) {
+                pr_debug("iscsi_target_sk_state_change got failed state\n");
+                schedule_delayed_work(&conn->login_cleanup_work, 0);
+                return;
+        }
+        orig_state_change(sk);
+}
+
 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)
@@ -860,6 +944,21 @@ static int iscsi_target_do_login(struct iscsi_conn *conn, struct iscsi_login *lo
                 break;
         }
 
+        if (conn->sock) {
+                struct sock *sk = conn->sock->sk;
+                bool state;
+
+                read_lock_bh(&sk->sk_callback_lock);
+                state = iscsi_target_sk_state_check(sk);
+                read_unlock_bh(&sk->sk_callback_lock);
+
+                if (!state) {
+                        pr_debug("iscsi_target_do_login() failed state for"
+                                 " conn: %p\n", conn);
+                        return -1;
+                }
+        }
+
         return 0;
 }
 
@@ -896,6 +995,7 @@ int iscsi_target_locate_portal(
         int sessiontype = 0, ret = 0;
 
         INIT_DELAYED_WORK(&conn->login_work, iscsi_target_do_login_rx);
+        INIT_DELAYED_WORK(&conn->login_cleanup_work, iscsi_target_do_cleanup);
         iscsi_target_set_sock_callbacks(conn);
 
         login->np = np;
@@ -1113,6 +1213,7 @@ int iscsi_target_start_negotiation(
                 }
         } else if (ret < 0) {
                 cancel_delayed_work_sync(&conn->login_work);
+                cancel_delayed_work_sync(&conn->login_cleanup_work);
                 iscsi_target_restore_sock_callbacks(conn);
                 iscsi_remove_failed_auth_entry(conn);
         }