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![Nicholas Bellinger](/assets/img/avatar_default.png)
This patch fixes bug where early se_cmd exceptions that occur before backend execution can result in use-after-free if/when a subsequent ABORT_TASK occurs for the same tag. Since an early se_cmd exception will have had se_cmd added to se_session->sess_cmd_list via target_get_sess_cmd(), it will not have CMD_T_COMPLETE set by the usual target_complete_cmd() backend completion path. This causes a subsequent ABORT_TASK + __target_check_io_state() to signal ABORT_TASK should proceed. As core_tmr_abort_task() executes, it will bring the outstanding se_cmd->cmd_kref count down to zero releasing se_cmd, after se_cmd has already been queued with error status into fabric driver response path code. To address this bug, introduce a CMD_T_PRE_EXECUTE bit that is set at target_get_sess_cmd() time, and cleared immediately before backend driver dispatch in target_execute_cmd() once CMD_T_ACTIVE is set. Then, check CMD_T_PRE_EXECUTE within __target_check_io_state() to determine when an early exception has occured, and avoid aborting this se_cmd since it will have already been queued into fabric driver response path code. Reported-by: Donald White <dew@datera.io> Cc: Donald White <dew@datera.io> Cc: Mike Christie <mchristi@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: stable@vger.kernel.org # 3.14+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
453 lines
13 KiB
C
453 lines
13 KiB
C
/*******************************************************************************
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* Filename: target_core_tmr.c
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*
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* This file contains SPC-3 task management infrastructure
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*
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* (c) Copyright 2009-2013 Datera, Inc.
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*
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* Nicholas A. Bellinger <nab@kernel.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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******************************************************************************/
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/export.h>
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#include <target/target_core_base.h>
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#include <target/target_core_backend.h>
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#include <target/target_core_fabric.h>
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#include "target_core_internal.h"
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#include "target_core_alua.h"
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#include "target_core_pr.h"
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int core_tmr_alloc_req(
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struct se_cmd *se_cmd,
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void *fabric_tmr_ptr,
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u8 function,
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gfp_t gfp_flags)
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{
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struct se_tmr_req *tmr;
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tmr = kzalloc(sizeof(struct se_tmr_req), gfp_flags);
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if (!tmr) {
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pr_err("Unable to allocate struct se_tmr_req\n");
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return -ENOMEM;
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}
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se_cmd->se_cmd_flags |= SCF_SCSI_TMR_CDB;
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se_cmd->se_tmr_req = tmr;
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tmr->task_cmd = se_cmd;
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tmr->fabric_tmr_ptr = fabric_tmr_ptr;
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tmr->function = function;
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INIT_LIST_HEAD(&tmr->tmr_list);
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return 0;
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}
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EXPORT_SYMBOL(core_tmr_alloc_req);
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void core_tmr_release_req(struct se_tmr_req *tmr)
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{
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struct se_device *dev = tmr->tmr_dev;
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unsigned long flags;
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if (dev) {
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spin_lock_irqsave(&dev->se_tmr_lock, flags);
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list_del_init(&tmr->tmr_list);
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spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
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}
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kfree(tmr);
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}
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static int core_tmr_handle_tas_abort(struct se_cmd *cmd, int tas)
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{
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unsigned long flags;
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bool remove = true, send_tas;
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/*
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* TASK ABORTED status (TAS) bit support
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*/
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spin_lock_irqsave(&cmd->t_state_lock, flags);
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send_tas = (cmd->transport_state & CMD_T_TAS);
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spin_unlock_irqrestore(&cmd->t_state_lock, flags);
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if (send_tas) {
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remove = false;
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transport_send_task_abort(cmd);
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}
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return transport_cmd_finish_abort(cmd, remove);
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}
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static int target_check_cdb_and_preempt(struct list_head *list,
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struct se_cmd *cmd)
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{
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struct t10_pr_registration *reg;
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if (!list)
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return 0;
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list_for_each_entry(reg, list, pr_reg_abort_list) {
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if (reg->pr_res_key == cmd->pr_res_key)
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return 0;
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}
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return 1;
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}
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static bool __target_check_io_state(struct se_cmd *se_cmd,
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struct se_session *tmr_sess, int tas)
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{
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struct se_session *sess = se_cmd->se_sess;
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assert_spin_locked(&sess->sess_cmd_lock);
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WARN_ON_ONCE(!irqs_disabled());
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/*
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* If command already reached CMD_T_COMPLETE state within
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* target_complete_cmd() or CMD_T_FABRIC_STOP due to shutdown,
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* this se_cmd has been passed to fabric driver and will
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* not be aborted.
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*
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* Otherwise, obtain a local se_cmd->cmd_kref now for TMR
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* ABORT_TASK + LUN_RESET for CMD_T_ABORTED processing as
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* long as se_cmd->cmd_kref is still active unless zero.
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*/
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spin_lock(&se_cmd->t_state_lock);
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if (se_cmd->transport_state & (CMD_T_COMPLETE | CMD_T_FABRIC_STOP)) {
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pr_debug("Attempted to abort io tag: %llu already complete or"
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" fabric stop, skipping\n", se_cmd->tag);
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spin_unlock(&se_cmd->t_state_lock);
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return false;
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}
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if (se_cmd->transport_state & CMD_T_PRE_EXECUTE) {
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if (se_cmd->scsi_status) {
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pr_debug("Attempted to abort io tag: %llu early failure"
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" status: 0x%02x\n", se_cmd->tag,
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se_cmd->scsi_status);
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spin_unlock(&se_cmd->t_state_lock);
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return false;
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}
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}
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if (sess->sess_tearing_down || se_cmd->cmd_wait_set) {
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pr_debug("Attempted to abort io tag: %llu already shutdown,"
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" skipping\n", se_cmd->tag);
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spin_unlock(&se_cmd->t_state_lock);
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return false;
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}
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se_cmd->transport_state |= CMD_T_ABORTED;
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if ((tmr_sess != se_cmd->se_sess) && tas)
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se_cmd->transport_state |= CMD_T_TAS;
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spin_unlock(&se_cmd->t_state_lock);
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return kref_get_unless_zero(&se_cmd->cmd_kref);
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}
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void core_tmr_abort_task(
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struct se_device *dev,
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struct se_tmr_req *tmr,
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struct se_session *se_sess)
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{
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struct se_cmd *se_cmd;
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unsigned long flags;
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u64 ref_tag;
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spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
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list_for_each_entry(se_cmd, &se_sess->sess_cmd_list, se_cmd_list) {
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if (dev != se_cmd->se_dev)
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continue;
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/* skip task management functions, including tmr->task_cmd */
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if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
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continue;
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ref_tag = se_cmd->tag;
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if (tmr->ref_task_tag != ref_tag)
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continue;
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printk("ABORT_TASK: Found referenced %s task_tag: %llu\n",
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se_cmd->se_tfo->get_fabric_name(), ref_tag);
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if (!__target_check_io_state(se_cmd, se_sess, 0))
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continue;
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list_del_init(&se_cmd->se_cmd_list);
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spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
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cancel_work_sync(&se_cmd->work);
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transport_wait_for_tasks(se_cmd);
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if (!transport_cmd_finish_abort(se_cmd, true))
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target_put_sess_cmd(se_cmd);
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printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"
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" ref_tag: %llu\n", ref_tag);
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tmr->response = TMR_FUNCTION_COMPLETE;
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atomic_long_inc(&dev->aborts_complete);
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return;
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}
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spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
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printk("ABORT_TASK: Sending TMR_TASK_DOES_NOT_EXIST for ref_tag: %lld\n",
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tmr->ref_task_tag);
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tmr->response = TMR_TASK_DOES_NOT_EXIST;
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atomic_long_inc(&dev->aborts_no_task);
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}
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static void core_tmr_drain_tmr_list(
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struct se_device *dev,
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struct se_tmr_req *tmr,
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struct list_head *preempt_and_abort_list)
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{
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LIST_HEAD(drain_tmr_list);
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struct se_session *sess;
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struct se_tmr_req *tmr_p, *tmr_pp;
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struct se_cmd *cmd;
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unsigned long flags;
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bool rc;
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/*
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* Release all pending and outgoing TMRs aside from the received
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* LUN_RESET tmr..
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*/
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spin_lock_irqsave(&dev->se_tmr_lock, flags);
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if (tmr)
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list_del_init(&tmr->tmr_list);
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list_for_each_entry_safe(tmr_p, tmr_pp, &dev->dev_tmr_list, tmr_list) {
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cmd = tmr_p->task_cmd;
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if (!cmd) {
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pr_err("Unable to locate struct se_cmd for TMR\n");
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continue;
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}
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/*
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* If this function was called with a valid pr_res_key
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* parameter (eg: for PROUT PREEMPT_AND_ABORT service action
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* skip non registration key matching TMRs.
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*/
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if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))
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continue;
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sess = cmd->se_sess;
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if (WARN_ON_ONCE(!sess))
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continue;
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spin_lock(&sess->sess_cmd_lock);
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spin_lock(&cmd->t_state_lock);
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if (!(cmd->transport_state & CMD_T_ACTIVE) ||
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(cmd->transport_state & CMD_T_FABRIC_STOP)) {
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spin_unlock(&cmd->t_state_lock);
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spin_unlock(&sess->sess_cmd_lock);
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continue;
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}
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if (cmd->t_state == TRANSPORT_ISTATE_PROCESSING) {
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spin_unlock(&cmd->t_state_lock);
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spin_unlock(&sess->sess_cmd_lock);
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continue;
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}
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if (sess->sess_tearing_down || cmd->cmd_wait_set) {
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spin_unlock(&cmd->t_state_lock);
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spin_unlock(&sess->sess_cmd_lock);
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continue;
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}
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cmd->transport_state |= CMD_T_ABORTED;
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spin_unlock(&cmd->t_state_lock);
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rc = kref_get_unless_zero(&cmd->cmd_kref);
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if (!rc) {
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printk("LUN_RESET TMR: non-zero kref_get_unless_zero\n");
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spin_unlock(&sess->sess_cmd_lock);
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continue;
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}
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spin_unlock(&sess->sess_cmd_lock);
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list_move_tail(&tmr_p->tmr_list, &drain_tmr_list);
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}
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spin_unlock_irqrestore(&dev->se_tmr_lock, flags);
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list_for_each_entry_safe(tmr_p, tmr_pp, &drain_tmr_list, tmr_list) {
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list_del_init(&tmr_p->tmr_list);
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cmd = tmr_p->task_cmd;
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pr_debug("LUN_RESET: %s releasing TMR %p Function: 0x%02x,"
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" Response: 0x%02x, t_state: %d\n",
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(preempt_and_abort_list) ? "Preempt" : "", tmr_p,
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tmr_p->function, tmr_p->response, cmd->t_state);
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cancel_work_sync(&cmd->work);
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transport_wait_for_tasks(cmd);
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if (!transport_cmd_finish_abort(cmd, 1))
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target_put_sess_cmd(cmd);
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}
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}
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static void core_tmr_drain_state_list(
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struct se_device *dev,
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struct se_cmd *prout_cmd,
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struct se_session *tmr_sess,
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int tas,
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struct list_head *preempt_and_abort_list)
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{
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LIST_HEAD(drain_task_list);
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struct se_session *sess;
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struct se_cmd *cmd, *next;
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unsigned long flags;
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int rc;
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/*
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* Complete outstanding commands with TASK_ABORTED SAM status.
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*
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* This is following sam4r17, section 5.6 Aborting commands, Table 38
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* for TMR LUN_RESET:
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*
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* a) "Yes" indicates that each command that is aborted on an I_T nexus
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* other than the one that caused the SCSI device condition is
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* completed with TASK ABORTED status, if the TAS bit is set to one in
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* the Control mode page (see SPC-4). "No" indicates that no status is
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* returned for aborted commands.
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*
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* d) If the logical unit reset is caused by a particular I_T nexus
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* (e.g., by a LOGICAL UNIT RESET task management function), then "yes"
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* (TASK_ABORTED status) applies.
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*
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* Otherwise (e.g., if triggered by a hard reset), "no"
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* (no TASK_ABORTED SAM status) applies.
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*
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* Note that this seems to be independent of TAS (Task Aborted Status)
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* in the Control Mode Page.
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*/
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spin_lock_irqsave(&dev->execute_task_lock, flags);
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list_for_each_entry_safe(cmd, next, &dev->state_list, state_list) {
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/*
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* For PREEMPT_AND_ABORT usage, only process commands
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* with a matching reservation key.
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*/
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if (target_check_cdb_and_preempt(preempt_and_abort_list, cmd))
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continue;
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/*
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* Not aborting PROUT PREEMPT_AND_ABORT CDB..
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*/
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if (prout_cmd == cmd)
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continue;
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sess = cmd->se_sess;
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if (WARN_ON_ONCE(!sess))
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continue;
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spin_lock(&sess->sess_cmd_lock);
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rc = __target_check_io_state(cmd, tmr_sess, tas);
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spin_unlock(&sess->sess_cmd_lock);
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if (!rc)
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continue;
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list_move_tail(&cmd->state_list, &drain_task_list);
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cmd->state_active = false;
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}
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spin_unlock_irqrestore(&dev->execute_task_lock, flags);
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while (!list_empty(&drain_task_list)) {
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cmd = list_entry(drain_task_list.next, struct se_cmd, state_list);
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list_del_init(&cmd->state_list);
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target_show_cmd("LUN_RESET: ", cmd);
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pr_debug("LUN_RESET: ITT[0x%08llx] - %s pr_res_key: 0x%016Lx\n",
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cmd->tag, (preempt_and_abort_list) ? "preempt" : "",
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cmd->pr_res_key);
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/*
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* If the command may be queued onto a workqueue cancel it now.
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*
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* This is equivalent to removal from the execute queue in the
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* loop above, but we do it down here given that
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* cancel_work_sync may block.
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*/
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cancel_work_sync(&cmd->work);
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transport_wait_for_tasks(cmd);
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if (!core_tmr_handle_tas_abort(cmd, tas))
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target_put_sess_cmd(cmd);
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}
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}
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int core_tmr_lun_reset(
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struct se_device *dev,
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struct se_tmr_req *tmr,
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struct list_head *preempt_and_abort_list,
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struct se_cmd *prout_cmd)
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{
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struct se_node_acl *tmr_nacl = NULL;
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struct se_portal_group *tmr_tpg = NULL;
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struct se_session *tmr_sess = NULL;
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int tas;
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/*
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* TASK_ABORTED status bit, this is configurable via ConfigFS
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* struct se_device attributes. spc4r17 section 7.4.6 Control mode page
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*
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* A task aborted status (TAS) bit set to zero specifies that aborted
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* tasks shall be terminated by the device server without any response
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* to the application client. A TAS bit set to one specifies that tasks
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* aborted by the actions of an I_T nexus other than the I_T nexus on
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* which the command was received shall be completed with TASK ABORTED
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* status (see SAM-4).
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*/
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tas = dev->dev_attrib.emulate_tas;
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/*
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* Determine if this se_tmr is coming from a $FABRIC_MOD
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* or struct se_device passthrough..
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*/
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if (tmr && tmr->task_cmd && tmr->task_cmd->se_sess) {
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tmr_sess = tmr->task_cmd->se_sess;
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tmr_nacl = tmr_sess->se_node_acl;
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tmr_tpg = tmr_sess->se_tpg;
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if (tmr_nacl && tmr_tpg) {
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pr_debug("LUN_RESET: TMR caller fabric: %s"
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" initiator port %s\n",
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tmr_tpg->se_tpg_tfo->get_fabric_name(),
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tmr_nacl->initiatorname);
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}
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}
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pr_debug("LUN_RESET: %s starting for [%s], tas: %d\n",
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(preempt_and_abort_list) ? "Preempt" : "TMR",
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dev->transport->name, tas);
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core_tmr_drain_tmr_list(dev, tmr, preempt_and_abort_list);
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core_tmr_drain_state_list(dev, prout_cmd, tmr_sess, tas,
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preempt_and_abort_list);
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/*
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* Clear any legacy SPC-2 reservation when called during
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* LOGICAL UNIT RESET
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*/
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if (!preempt_and_abort_list &&
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(dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)) {
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spin_lock(&dev->dev_reservation_lock);
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dev->dev_reserved_node_acl = NULL;
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dev->dev_reservation_flags &= ~DRF_SPC2_RESERVATIONS;
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spin_unlock(&dev->dev_reservation_lock);
|
|
pr_debug("LUN_RESET: SCSI-2 Released reservation\n");
|
|
}
|
|
|
|
atomic_long_inc(&dev->num_resets);
|
|
|
|
pr_debug("LUN_RESET: %s for [%s] Complete\n",
|
|
(preempt_and_abort_list) ? "Preempt" : "TMR",
|
|
dev->transport->name);
|
|
return 0;
|
|
}
|
|
|