From: Lee Duncan <lduncan@xxxxxxxx>
If there is an error queueing an iscsi command in
iscsi_queuecommand(), for example if the transport fails
to take the command in sessuin->tt->xmit_task(), then
the error path can call iscsi_complete_task() without
first aquiring the back_lock as required. This can
lead to things like ITT pool can get corrupt, resulting
in duplicate ITTs being sent out.
The solution is to hold the back_lock around
iscsi_complete_task() calls, and to add a little commenting
to help others understand when back_lock must be held.
Signed-off-by: Lee Duncan <lduncan@xxxxxxxx>
---
drivers/scsi/libiscsi.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index b8d325ce8754..ef7871e8c6bd 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -838,7 +838,7 @@ EXPORT_SYMBOL_GPL(iscsi_conn_send_pdu);
* @datalen: len of buffer
*
* iscsi_cmd_rsp sets up the scsi_cmnd fields based on the PDU and
- * then completes the command and task.
+ * then completes the command and task. called under back_lock
**/
static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
struct iscsi_task *task, char *data,
@@ -941,6 +941,9 @@ static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
* @conn: iscsi connection
* @hdr: iscsi pdu
* @task: scsi command task
+ *
+ * iscsi_data_in_rsp sets up the scsi_cmnd fields based on the data received
+ * then completes the command and task. called under back_lock
**/
static void
iscsi_data_in_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
@@ -1025,6 +1028,16 @@ static int iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
return 0;
}
+/**
+ * iscsi_nop_out_rsp - SCSI NOP Response processing
+ * @task: scsi command task
+ * @nop: the nop structure
+ * @data: where to put the data
+ * @datalen: length of data
+ *
+ * iscsi_nop_out_rsp handles nop response from use or
+ * from user space. called under back_lock
+ **/
static int iscsi_nop_out_rsp(struct iscsi_task *task,
struct iscsi_nopin *nop, char *data, int datalen)
{
@@ -1791,7 +1804,9 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
return 0;
prepd_reject:
+ spin_lock_bh(&session->back_lock);
iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
+ spin_unlock_bh(&session->back_lock);
reject:
spin_unlock_bh(&session->frwd_lock);
ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n",
@@ -1799,7 +1814,9 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
return SCSI_MLQUEUE_TARGET_BUSY;
prepd_fault:
+ spin_lock_bh(&session->back_lock);
iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
+ spin_unlock_bh(&session->back_lock);
fault:
spin_unlock_bh(&session->frwd_lock);
ISCSI_DBG_SESSION(session, "iscsi: cmd 0x%x is not queued (%d)\n",
@@ -3121,8 +3138,9 @@ fail_mgmt_tasks(struct iscsi_session *session, struct iscsi_conn *conn)
state = ISCSI_TASK_ABRT_SESS_RECOV;
if (task->state == ISCSI_TASK_PENDING)
state = ISCSI_TASK_COMPLETED;
+ spin_lock_bh(&session->back_lock);
iscsi_complete_task(task, state);
-
+ spin_unlock_bh(&session->back_lock);
}
}
--
2.16.4
