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alistair23-linux
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target: Drop se_lun->lun_active for existing percpu lun_ref 

With se_port_t and t10_alua_tg_pt_gp_member being absored into se_lun,
there is no need for an extra atomic_t based reference count for PR
ALL_TG_PT=1 and ALUA access state transition.

Go ahead and use the existing percpu se_lun->lun_ref instead, and
convert the two special cases to percpu_ref_tryget_live() to avoid
se_lun if transport_clear_lun_ref() has already been invoked to
shutdown the se_lun.

Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
hifive-unleashed-5.1
Nicholas Bellinger 2015-05-20 21:21:08 -07:00
parent 4cc987eaff
commit 9e37d042cf
4 changed files with 14 additions and 11 deletions
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5
drivers/target/target_core_alua.c
View File

@ -969,7 +969,8 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
* every I_T nexus other than the I_T nexus on which the SET
* TARGET PORT GROUPS command
*/
atomic_inc_mb(&lun->lun_active);
if (!percpu_ref_tryget_live(&lun->lun_ref))
continue;
spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
spin_lock_bh(&lun->lun_deve_lock);
@ -998,7 +999,7 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
spin_unlock_bh(&lun->lun_deve_lock);
spin_lock(&tg_pt_gp->tg_pt_gp_lock);
atomic_dec_mb(&lun->lun_active);
percpu_ref_put(&lun->lun_ref);
}
spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
/*

9
drivers/target/target_core_pr.c
View File

@ -704,7 +704,8 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
*/
spin_lock(&dev->se_port_lock);
list_for_each_entry_safe(lun_tmp, next, &dev->dev_sep_list, lun_dev_link) {
atomic_inc_mb(&lun_tmp->lun_active);
if (!percpu_ref_tryget_live(&lun_tmp->lun_ref))
continue;
spin_unlock(&dev->se_port_lock);
spin_lock_bh(&lun_tmp->lun_deve_lock);
@ -751,7 +752,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
if (ret < 0) {
pr_err("core_scsi3_lunacl_depend"
"_item() failed\n");
atomic_dec_mb(&lun->lun_active);
percpu_ref_put(&lun_tmp->lun_ref);
kref_put(&deve_tmp->pr_kref, target_pr_kref_release);
goto out;
}
@ -770,7 +771,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
deve_tmp->mapped_lun, NULL,
sa_res_key, all_tg_pt, aptpl);
if (!pr_reg_atp) {
atomic_dec_mb(&lun_tmp->lun_active);
percpu_ref_put(&lun_tmp->lun_ref);
core_scsi3_lunacl_undepend_item(deve_tmp);
goto out;
}
@ -782,7 +783,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
spin_unlock_bh(&lun_tmp->lun_deve_lock);
spin_lock(&dev->se_port_lock);
atomic_dec_mb(&lun_tmp->lun_active);
percpu_ref_put(&lun_tmp->lun_ref);
}
spin_unlock(&dev->se_port_lock);

10
drivers/target/target_core_tpg.c
View File

@ -607,7 +607,6 @@ struct se_lun *core_tpg_alloc_lun(
mutex_init(&lun->lun_tg_pt_md_mutex);
INIT_LIST_HEAD(&lun->lun_tg_pt_gp_link);
spin_lock_init(&lun->lun_tg_pt_gp_lock);
atomic_set(&lun->lun_active, 0);
lun->lun_tpg = tpg;
return lun;
@ -667,13 +666,16 @@ void core_tpg_remove_lun(
struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
core_clear_lun_from_tpg(lun, tpg);
/*
* Wait for any active I/O references to percpu se_lun->lun_ref to
* be released. Also, se_lun->lun_ref is now used by PR and ALUA
* logic when referencing a remote target port during ALL_TGT_PT=1
* and generating UNIT_ATTENTIONs for ALUA access state transition.
*/
transport_clear_lun_ref(lun);
mutex_lock(&tpg->tpg_lun_mutex);
if (lun->lun_se_dev) {
while (atomic_read(&lun->lun_active))
cpu_relax();
target_detach_tg_pt_gp(lun);
spin_lock(&dev->se_port_lock);

1
include/target/target_core_base.h
View File

@ -721,7 +721,6 @@ struct se_lun {
struct t10_alua_tg_pt_gp *lun_tg_pt_gp;
spinlock_t lun_tg_pt_gp_lock;
atomic_t lun_active;
struct se_portal_group *lun_tpg;
struct scsi_port_stats lun_stats;
struct config_group lun_group;