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Subject[PATCH 4.9 38/39] qla2xxx: Fix incorrect tcm_qla2xxx_free_cmd use during TMR ABORT (v2)
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit 6bcbb3174caa5f1ccc894f8ae077631659d5a629 upstream.

This patch drops two incorrect usages of tcm_qla2xxx_free_cmd()
during TMR ABORT within tcm_qla2xxx_handle_data_work() and
tcm_qla2xxx_aborted_task(), which where attempting to dispatch
into workqueue context to do tcm_qla2xxx_complete_free() and
subsequently invoke transport_generic_free_cmd().

This is incorrect because during TMR ABORT target-core will
drop the outstanding se_cmd->cmd_kref references once it has
quiesced the se_cmd via transport_wait_for_tasks(), and in
the case of qla2xxx it should not attempt to do it's own
transport_generic_free_cmd() once the abort has occured.

As reported by Pascal, this was originally manifesting as a
BUG_ON(cmd->cmd_in_wq) in qlt_free_cmd() during TMR ABORT,
with a LIO backend that had sufficently high enough WRITE
latency to trigger a host side TMR ABORT_TASK.

(v2: Drop the qla_tgt_cmd->write_pending_abort_comp changes,
as they will be addressed in a seperate series)

Reported-by: Pascal de Bruijn <p.debruijn@unilogic.nl>
Tested-by: Pascal de Bruijn <p.debruijn@unilogic.nl>
Cc: Pascal de Bruijn <p.debruijn@unilogic.nl>
Reported-by: Lukasz Engel <lukasz.engel@softax.pl>
Cc: Lukasz Engel <lukasz.engel@softax.pl>
Acked-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Cc: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
drivers/scsi/qla2xxx/tcm_qla2xxx.c | 33 ---------------------------------
1 file changed, 33 deletions(-)

--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
@@ -484,7 +484,6 @@ static int tcm_qla2xxx_handle_cmd(scsi_q
static void tcm_qla2xxx_handle_data_work(struct work_struct *work)
{
struct qla_tgt_cmd *cmd = container_of(work, struct qla_tgt_cmd, work);
- unsigned long flags;

/*
* Ensure that the complete FCP WRITE payload has been received.
@@ -492,17 +491,6 @@ static void tcm_qla2xxx_handle_data_work
*/
cmd->cmd_in_wq = 0;

- spin_lock_irqsave(&cmd->cmd_lock, flags);
- cmd->cmd_flags |= CMD_FLAG_DATA_WORK;
- if (cmd->aborted) {
- cmd->cmd_flags |= CMD_FLAG_DATA_WORK_FREE;
- spin_unlock_irqrestore(&cmd->cmd_lock, flags);
-
- tcm_qla2xxx_free_cmd(cmd);
- return;
- }
- spin_unlock_irqrestore(&cmd->cmd_lock, flags);
-
cmd->vha->tgt_counters.qla_core_ret_ctio++;
if (!cmd->write_data_transferred) {
/*
@@ -682,34 +670,13 @@ static void tcm_qla2xxx_queue_tm_rsp(str
qlt_xmit_tm_rsp(mcmd);
}

-
-#define DATA_WORK_NOT_FREE(_flags) \
- (( _flags & (CMD_FLAG_DATA_WORK|CMD_FLAG_DATA_WORK_FREE)) == \
- CMD_FLAG_DATA_WORK)
static void tcm_qla2xxx_aborted_task(struct se_cmd *se_cmd)
{
struct qla_tgt_cmd *cmd = container_of(se_cmd,
struct qla_tgt_cmd, se_cmd);
- unsigned long flags;

if (qlt_abort_cmd(cmd))
return;
-
- spin_lock_irqsave(&cmd->cmd_lock, flags);
- if ((cmd->state == QLA_TGT_STATE_NEW)||
- ((cmd->state == QLA_TGT_STATE_DATA_IN) &&
- DATA_WORK_NOT_FREE(cmd->cmd_flags)) ) {
-
- cmd->cmd_flags |= CMD_FLAG_DATA_WORK_FREE;
- spin_unlock_irqrestore(&cmd->cmd_lock, flags);
- /* Cmd have not reached firmware.
- * Use this trigger to free it. */
- tcm_qla2xxx_free_cmd(cmd);
- return;
- }
- spin_unlock_irqrestore(&cmd->cmd_lock, flags);
- return;
-
}

static void tcm_qla2xxx_clear_sess_lookup(struct tcm_qla2xxx_lport *,

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