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target: Fix ALUA transition state race between multiple initiators
Multiple threads could be writing to alua_access_state at the same time, or there could be multiple STPGs in flight (different initiators sending them or one initiator sending them to different ports), or a combo of both and the core_alua_do_transition_tg_pt calls will race with each other. Because from the last patches we no longer delay running core_alua_do_transition_tg_pt_work, there does not seem to be any point in running that in a workqueue. And, we always wait for it to complete one way or another, so we can sleep in this code path. So, this patch made over target-pending just adds a mutex and does the work core_alua_do_transition_tg_pt_work was doing in core_alua_do_transition_tg_pt. There is also no need to use an atomic for the tg_pt_gp_alua_access_state. In core_alua_do_transition_tg_pt we will test and set it under the transition mutex. And, it is a int/32 bits so in the other places where it is read, we will never see it partially updated. Signed-off-by: Mike Christie <mchristi@redhat.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Mike Christie
Nicholas Bellinger
parent
7a56dc8888
commit
d19c4643a5
@ -197,8 +197,7 @@ target_emulate_report_target_port_groups(struct se_cmd *cmd)
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/*
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* Set the ASYMMETRIC ACCESS State
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*/
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buf[off++] |= (atomic_read(
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&tg_pt_gp->tg_pt_gp_alua_access_state) & 0xff);
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buf[off++] |= tg_pt_gp->tg_pt_gp_alua_access_state & 0xff;
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/*
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* Set supported ASYMMETRIC ACCESS State bits
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*/
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@ -710,7 +709,7 @@ target_alua_state_check(struct se_cmd *cmd)
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spin_lock(&lun->lun_tg_pt_gp_lock);
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tg_pt_gp = lun->lun_tg_pt_gp;
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out_alua_state = atomic_read(&tg_pt_gp->tg_pt_gp_alua_access_state);
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out_alua_state = tg_pt_gp->tg_pt_gp_alua_access_state;
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nonop_delay_msecs = tg_pt_gp->tg_pt_gp_nonop_delay_msecs;
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// XXX: keeps using tg_pt_gp witout reference after unlock
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@ -911,7 +910,7 @@ static int core_alua_write_tpg_metadata(
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}
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/*
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* Called with tg_pt_gp->tg_pt_gp_md_mutex held
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* Called with tg_pt_gp->tg_pt_gp_transition_mutex held
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*/
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static int core_alua_update_tpg_primary_metadata(
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struct t10_alua_tg_pt_gp *tg_pt_gp)
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@ -934,7 +933,7 @@ static int core_alua_update_tpg_primary_metadata(
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"alua_access_state=0x%02x\n"
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"alua_access_status=0x%02x\n",
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tg_pt_gp->tg_pt_gp_id,
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tg_pt_gp->tg_pt_gp_alua_pending_state,
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tg_pt_gp->tg_pt_gp_alua_access_state,
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tg_pt_gp->tg_pt_gp_alua_access_status);
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snprintf(path, ALUA_METADATA_PATH_LEN,
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@ -1013,13 +1012,52 @@ static void core_alua_queue_state_change_ua(struct t10_alua_tg_pt_gp *tg_pt_gp)
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spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
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}
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static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
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static int core_alua_do_transition_tg_pt(
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struct t10_alua_tg_pt_gp *tg_pt_gp,
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int new_state,
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int explicit)
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{
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struct t10_alua_tg_pt_gp *tg_pt_gp = container_of(work,
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struct t10_alua_tg_pt_gp, tg_pt_gp_transition_work);
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struct se_device *dev = tg_pt_gp->tg_pt_gp_dev;
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bool explicit = (tg_pt_gp->tg_pt_gp_alua_access_status ==
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ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG);
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int prev_state;
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mutex_lock(&tg_pt_gp->tg_pt_gp_transition_mutex);
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/* Nothing to be done here */
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if (tg_pt_gp->tg_pt_gp_alua_access_state == new_state) {
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mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
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return 0;
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}
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if (explicit && new_state == ALUA_ACCESS_STATE_TRANSITION) {
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mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
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return -EAGAIN;
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}
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/*
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* Save the old primary ALUA access state, and set the current state
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* to ALUA_ACCESS_STATE_TRANSITION.
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*/
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prev_state = tg_pt_gp->tg_pt_gp_alua_access_state;
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tg_pt_gp->tg_pt_gp_alua_access_state = ALUA_ACCESS_STATE_TRANSITION;
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tg_pt_gp->tg_pt_gp_alua_access_status = (explicit) ?
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ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG :
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ALUA_STATUS_ALTERED_BY_IMPLICIT_ALUA;
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core_alua_queue_state_change_ua(tg_pt_gp);
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if (new_state == ALUA_ACCESS_STATE_TRANSITION) {
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mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
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return 0;
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}
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/*
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* Check for the optional ALUA primary state transition delay
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*/
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if (tg_pt_gp->tg_pt_gp_trans_delay_msecs != 0)
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msleep_interruptible(tg_pt_gp->tg_pt_gp_trans_delay_msecs);
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/*
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* Set the current primary ALUA access state to the requested new state
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*/
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tg_pt_gp->tg_pt_gp_alua_access_state = new_state;
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/*
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* Update the ALUA metadata buf that has been allocated in
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@ -1034,93 +1072,19 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
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* struct file does NOT affect the actual ALUA transition.
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*/
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if (tg_pt_gp->tg_pt_gp_write_metadata) {
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mutex_lock(&tg_pt_gp->tg_pt_gp_md_mutex);
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core_alua_update_tpg_primary_metadata(tg_pt_gp);
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mutex_unlock(&tg_pt_gp->tg_pt_gp_md_mutex);
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}
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/*
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* Set the current primary ALUA access state to the requested new state
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*/
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atomic_set(&tg_pt_gp->tg_pt_gp_alua_access_state,
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tg_pt_gp->tg_pt_gp_alua_pending_state);
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pr_debug("Successful %s ALUA transition TG PT Group: %s ID: %hu"
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" from primary access state %s to %s\n", (explicit) ? "explicit" :
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"implicit", config_item_name(&tg_pt_gp->tg_pt_gp_group.cg_item),
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tg_pt_gp->tg_pt_gp_id,
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core_alua_dump_state(tg_pt_gp->tg_pt_gp_alua_previous_state),
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core_alua_dump_state(tg_pt_gp->tg_pt_gp_alua_pending_state));
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core_alua_dump_state(prev_state),
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core_alua_dump_state(new_state));
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core_alua_queue_state_change_ua(tg_pt_gp);
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spin_lock(&dev->t10_alua.tg_pt_gps_lock);
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atomic_dec(&tg_pt_gp->tg_pt_gp_ref_cnt);
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spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
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if (tg_pt_gp->tg_pt_gp_transition_complete)
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complete(tg_pt_gp->tg_pt_gp_transition_complete);
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}
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static int core_alua_do_transition_tg_pt(
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struct t10_alua_tg_pt_gp *tg_pt_gp,
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int new_state,
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int explicit)
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{
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struct se_device *dev = tg_pt_gp->tg_pt_gp_dev;
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DECLARE_COMPLETION_ONSTACK(wait);
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/* Nothing to be done here */
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if (atomic_read(&tg_pt_gp->tg_pt_gp_alua_access_state) == new_state)
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return 0;
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if (explicit && new_state == ALUA_ACCESS_STATE_TRANSITION)
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return -EAGAIN;
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/*
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* Flush any pending transitions
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*/
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if (!explicit)
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flush_work(&tg_pt_gp->tg_pt_gp_transition_work);
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/*
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* Save the old primary ALUA access state, and set the current state
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* to ALUA_ACCESS_STATE_TRANSITION.
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*/
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atomic_set(&tg_pt_gp->tg_pt_gp_alua_access_state,
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ALUA_ACCESS_STATE_TRANSITION);
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tg_pt_gp->tg_pt_gp_alua_access_status = (explicit) ?
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ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG :
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ALUA_STATUS_ALTERED_BY_IMPLICIT_ALUA;
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core_alua_queue_state_change_ua(tg_pt_gp);
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if (new_state == ALUA_ACCESS_STATE_TRANSITION)
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return 0;
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tg_pt_gp->tg_pt_gp_alua_previous_state =
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atomic_read(&tg_pt_gp->tg_pt_gp_alua_access_state);
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tg_pt_gp->tg_pt_gp_alua_pending_state = new_state;
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/*
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* Check for the optional ALUA primary state transition delay
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*/
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if (tg_pt_gp->tg_pt_gp_trans_delay_msecs != 0)
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msleep_interruptible(tg_pt_gp->tg_pt_gp_trans_delay_msecs);
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/*
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* Take a reference for workqueue item
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*/
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spin_lock(&dev->t10_alua.tg_pt_gps_lock);
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atomic_inc(&tg_pt_gp->tg_pt_gp_ref_cnt);
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spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
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schedule_work(&tg_pt_gp->tg_pt_gp_transition_work);
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if (explicit) {
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tg_pt_gp->tg_pt_gp_transition_complete = &wait;
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wait_for_completion(&wait);
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tg_pt_gp->tg_pt_gp_transition_complete = NULL;
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}
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mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
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return 0;
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}
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@ -1685,14 +1649,12 @@ struct t10_alua_tg_pt_gp *core_alua_allocate_tg_pt_gp(struct se_device *dev,
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}
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INIT_LIST_HEAD(&tg_pt_gp->tg_pt_gp_list);
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INIT_LIST_HEAD(&tg_pt_gp->tg_pt_gp_lun_list);
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mutex_init(&tg_pt_gp->tg_pt_gp_md_mutex);
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mutex_init(&tg_pt_gp->tg_pt_gp_transition_mutex);
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spin_lock_init(&tg_pt_gp->tg_pt_gp_lock);
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atomic_set(&tg_pt_gp->tg_pt_gp_ref_cnt, 0);
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INIT_WORK(&tg_pt_gp->tg_pt_gp_transition_work,
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core_alua_do_transition_tg_pt_work);
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tg_pt_gp->tg_pt_gp_dev = dev;
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atomic_set(&tg_pt_gp->tg_pt_gp_alua_access_state,
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ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED);
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tg_pt_gp->tg_pt_gp_alua_access_state =
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ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED;
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/*
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* Enable both explicit and implicit ALUA support by default
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*/
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@ -1797,8 +1759,6 @@ void core_alua_free_tg_pt_gp(
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dev->t10_alua.alua_tg_pt_gps_counter--;
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spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
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flush_work(&tg_pt_gp->tg_pt_gp_transition_work);
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/*
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* Allow a struct t10_alua_tg_pt_gp_member * referenced by
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* core_alua_get_tg_pt_gp_by_name() in
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@ -1938,8 +1898,8 @@ ssize_t core_alua_show_tg_pt_gp_info(struct se_lun *lun, char *page)
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"Primary Access Status: %s\nTG Port Secondary Access"
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" State: %s\nTG Port Secondary Access Status: %s\n",
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config_item_name(tg_pt_ci), tg_pt_gp->tg_pt_gp_id,
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core_alua_dump_state(atomic_read(
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&tg_pt_gp->tg_pt_gp_alua_access_state)),
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core_alua_dump_state(
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tg_pt_gp->tg_pt_gp_alua_access_state),
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core_alua_dump_status(
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tg_pt_gp->tg_pt_gp_alua_access_status),
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atomic_read(&lun->lun_tg_pt_secondary_offline) ?
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@ -2392,7 +2392,7 @@ static ssize_t target_tg_pt_gp_alua_access_state_show(struct config_item *item,
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char *page)
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{
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return sprintf(page, "%d\n",
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atomic_read(&to_tg_pt_gp(item)->tg_pt_gp_alua_access_state));
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to_tg_pt_gp(item)->tg_pt_gp_alua_access_state);
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}
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static ssize_t target_tg_pt_gp_alua_access_state_store(struct config_item *item,
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@ -280,8 +280,6 @@ struct t10_alua_tg_pt_gp {
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u16 tg_pt_gp_id;
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int tg_pt_gp_valid_id;
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int tg_pt_gp_alua_supported_states;
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int tg_pt_gp_alua_pending_state;
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int tg_pt_gp_alua_previous_state;
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int tg_pt_gp_alua_access_status;
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int tg_pt_gp_alua_access_type;
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int tg_pt_gp_nonop_delay_msecs;
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@ -290,18 +288,16 @@ struct t10_alua_tg_pt_gp {
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int tg_pt_gp_pref;
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int tg_pt_gp_write_metadata;
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u32 tg_pt_gp_members;
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atomic_t tg_pt_gp_alua_access_state;
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int tg_pt_gp_alua_access_state;
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atomic_t tg_pt_gp_ref_cnt;
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spinlock_t tg_pt_gp_lock;
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struct mutex tg_pt_gp_md_mutex;
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struct mutex tg_pt_gp_transition_mutex;
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struct se_device *tg_pt_gp_dev;
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struct config_group tg_pt_gp_group;
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struct list_head tg_pt_gp_list;
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struct list_head tg_pt_gp_lun_list;
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struct se_lun *tg_pt_gp_alua_lun;
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struct se_node_acl *tg_pt_gp_alua_nacl;
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struct work_struct tg_pt_gp_transition_work;
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struct completion *tg_pt_gp_transition_complete;
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};
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struct t10_vpd {
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