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scsi: libiscsi: Hold back_lock when calling iscsi_complete_task

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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@suse.com>
Acked-by: Chris Leech <cleech@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Lee Duncan 2019-02-25 09:41:30 -08:00 committed by Martin K. Petersen
parent cf9efd5d92
commit a656183e6c
1 changed files with 20 additions and 2 deletions
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22
drivers/scsi/libiscsi.c
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@ -798,7 +798,7 @@ 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,
@ -894,6 +894,9 @@ out:
* @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,
@ -978,6 +981,16 @@ 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)
{
@ -1744,7 +1757,9 @@ 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",
@ -1752,7 +1767,9 @@ reject:
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",
@ -3069,8 +3086,9 @@ 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);
}
}