iscsi-target: Fix iser explicit logout TX kthread leak

This patch fixes a regression introduced with the following commit
in v4.0-rc1 code, where an explicit iser-target logout would result
in ->tx_thread_active being incorrectly cleared by the logout post
handler, and subsequent TX kthread leak:

    commit 88dcd2dab5c23b1c9cfc396246d8f476c872f0ca
    Author: Nicholas Bellinger <nab@linux-iscsi.org>
    Date:   Thu Feb 26 22:19:15 2015 -0800

        iscsi-target: Convert iscsi_thread_set usage to kthread.h

To address this bug, change iscsit_logout_post_handler_closesession()
and iscsit_logout_post_handler_samecid() to only cmpxchg() on
->tx_thread_active for traditional iscsi/tcp connections.

This is required because iscsi/tcp connections are invoking logout
post handler logic directly from TX kthread context, while iser
connections are invoking logout post handler logic from a seperate
workqueue context.

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

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 202a42858f2537e7aa8f790f3969ba570ad93208..cd77a064c772f1bbe897482d2372fe5bc6434328 100644 (file)
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -4544,7 +4544,18 @@ static void iscsit_logout_post_handler_closesession(
        struct iscsi_conn *conn)
 {
        struct iscsi_session *sess = conn->sess;
-       int sleep = cmpxchg(&conn->tx_thread_active, true, false);
+       int sleep = 1;
+       /*
+        * Traditional iscsi/tcp will invoke this logic from TX thread
+        * context during session logout, so clear tx_thread_active and
+        * sleep if iscsit_close_connection() has not already occured.
+        *
+        * Since iser-target invokes this logic from it's own workqueue,
+        * always sleep waiting for RX/TX thread shutdown to complete
+        * within iscsit_close_connection().
+        */
+       if (conn->conn_transport->transport_type == ISCSI_TCP)
+               sleep = cmpxchg(&conn->tx_thread_active, true, false);
 
        atomic_set(&conn->conn_logout_remove, 0);
        complete(&conn->conn_logout_comp);
@@ -4558,7 +4569,10 @@ static void iscsit_logout_post_handler_closesession(
 static void iscsit_logout_post_handler_samecid(
        struct iscsi_conn *conn)
 {
-       int sleep = cmpxchg(&conn->tx_thread_active, true, false);
+       int sleep = 1;
+
+       if (conn->conn_transport->transport_type == ISCSI_TCP)
+               sleep = cmpxchg(&conn->tx_thread_active, true, false);
 
        atomic_set(&conn->conn_logout_remove, 0);
        complete(&conn->conn_logout_comp);