linux-kernel - [PATCH 4.9 38/39] qla2xxx: Fix incorrect tcm_qla2xxx_free

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Message-Id: <20171116174214.850892154@linuxfoundation.org>
Date:   Thu, 16 Nov 2017 18:42:57 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pascal de Bruijn <p.debruijn@...logic.nl>,
        Lukasz Engel <lukasz.engel@...tax.pl>,
        Himanshu Madhani <himanshu.madhani@...ium.com>,
        Quinn Tran <quinn.tran@...ium.com>,
        Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH 4.9 38/39] qla2xxx: Fix incorrect tcm_qla2xxx_free_cmd use during TMR ABORT (v2)

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Nicholas Bellinger <nab@...ux-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@...logic.nl>
Tested-by: Pascal de Bruijn <p.debruijn@...logic.nl>
Cc: Pascal de Bruijn <p.debruijn@...logic.nl>
Reported-by: Lukasz Engel <lukasz.engel@...tax.pl>
Cc: Lukasz Engel <lukasz.engel@...tax.pl>
Acked-by: Himanshu Madhani <himanshu.madhani@...ium.com>
Cc: Quinn Tran <quinn.tran@...ium.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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 *,