[3.16.y-ckt stable] Patch "iser-target: Put the reference on commands waiting for unsol data" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    iser-target: Put the reference on commands waiting for unsol data

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.19.8-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 3080ce45edf1600cf38dadf6c1d34cb276a116d6 Mon Sep 17 00:00:00 2001
From: Jenny Derzhavetz <jennyf at mellanox.com>
Date: Sun, 6 Sep 2015 14:52:21 +0300
Subject: iser-target: Put the reference on commands waiting for unsol data

commit 3e03c4b01da3e6a5f3081eb0aa252490fe83e352 upstream.

The iscsi target core teardown sequence calls wait_conn for
all active commands to finish gracefully by:
- move the queue-pair to error state
- drain all the completions
- wait for the core to finish handling all session commands

However, when tearing down a session while there are sequenced
commands that are still waiting for unsolicited data outs, we can
block forever as these are missing an extra reference put.

We basically need the equivalent of iscsit_free_queue_reqs_for_conn()
which is called after wait_conn has returned. Address this by an
explicit walk on conn_cmd_list and put the extra reference.

Signed-off-by: Jenny Derzhavetz <jennyf at mellanox.com>
Signed-off-by: Sagi Grimberg <sagig at mellanox.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/infiniband/ulp/isert/ib_isert.c | 38 ++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index aee23d9..46563f1 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -3294,6 +3294,41 @@ isert_wait4flush(struct isert_conn *isert_conn)
 	wait_for_completion(&isert_conn->conn_wait_comp_err);
 }

+/**
+ * isert_put_unsol_pending_cmds() - Drop commands waiting for
+ *     unsolicitate dataout
+ * @conn:    iscsi connection
+ *
+ * We might still have commands that are waiting for unsolicited
+ * dataouts messages. We must put the extra reference on those
+ * before blocking on the target_wait_for_session_cmds
+ */
+static void
+isert_put_unsol_pending_cmds(struct iscsi_conn *conn)
+{
+	struct iscsi_cmd *cmd, *tmp;
+	static LIST_HEAD(drop_cmd_list);
+
+	spin_lock_bh(&conn->cmd_lock);
+	list_for_each_entry_safe(cmd, tmp, &conn->conn_cmd_list, i_conn_node) {
+		if ((cmd->cmd_flags & ICF_NON_IMMEDIATE_UNSOLICITED_DATA) &&
+		    (cmd->write_data_done < conn->sess->sess_ops->FirstBurstLength) &&
+		    (cmd->write_data_done < cmd->se_cmd.data_length))
+			list_move_tail(&cmd->i_conn_node, &drop_cmd_list);
+	}
+	spin_unlock_bh(&conn->cmd_lock);
+
+	list_for_each_entry_safe(cmd, tmp, &drop_cmd_list, i_conn_node) {
+		list_del_init(&cmd->i_conn_node);
+		if (cmd->i_state != ISTATE_REMOVE) {
+			struct isert_cmd *isert_cmd = iscsit_priv_cmd(cmd);
+
+			isert_info("conn %p dropping cmd %p\n", conn, cmd);
+			isert_put_cmd(isert_cmd, true);
+		}
+	}
+}
+
 static void isert_wait_conn(struct iscsi_conn *conn)
 {
 	struct isert_conn *isert_conn = conn->context;
@@ -3312,8 +3347,9 @@ static void isert_wait_conn(struct iscsi_conn *conn)
 	isert_conn_terminate(isert_conn);
 	mutex_unlock(&isert_conn->conn_mutex);

-	isert_wait4cmds(conn);
 	isert_wait4flush(isert_conn);
+	isert_put_unsol_pending_cmds(conn);
+	isert_wait4cmds(conn);
 	isert_wait4logout(isert_conn);

 	queue_work(isert_release_wq, &isert_conn->release_work);
--
1.9.1