scsi: qla2xxx: deadlock by configfs_depend_item

The intent of invoking configfs_depend_item in commit 7474f52a82d51
("tcm_qla2xxx: Perform configfs depend/undepend for base_tpg")
was to prevent a physical Fibre Channel port removal when
virtual (NPIV) ports announced through that physical port are active.
The change does not work as expected: it makes enabled physical port
dependent on target configfs subsystem (the port's parent), something
the configfs guarantees anyway.

Besides, scheduling work in a worker thread and waiting for the work's
completion is not really a valid workaround for the requirement not to call
configfs_depend_item from a configfs callback: the call occasionally
deadlocks.

Thus, removing configfs_depend_item calls does not break anything and fixes
the deadlock problem.

Signed-off-by: Anatoliy Glagolev <glagolig@gmail.com>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.c b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
index fc312a5eab751f8611fa13b677c4832e9fbf073d..283e6b80abb5a867b7da278cea4744f9349b3f9d 100644 (file)
--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.c
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.c
@@ -954,38 +954,14 @@ static ssize_t tcm_qla2xxx_tpg_enable_show(struct config_item *item,
                        atomic_read(&tpg->lport_tpg_enabled));
 }
 
-static void tcm_qla2xxx_depend_tpg(struct work_struct *work)
-{
-       struct tcm_qla2xxx_tpg *base_tpg = container_of(work,
-                               struct tcm_qla2xxx_tpg, tpg_base_work);
-       struct se_portal_group *se_tpg = &base_tpg->se_tpg;
-       struct scsi_qla_host *base_vha = base_tpg->lport->qla_vha;
-
-       if (!target_depend_item(&se_tpg->tpg_group.cg_item)) {
-               atomic_set(&base_tpg->lport_tpg_enabled, 1);
-               qlt_enable_vha(base_vha);
-       }
-       complete(&base_tpg->tpg_base_comp);
-}
-
-static void tcm_qla2xxx_undepend_tpg(struct work_struct *work)
-{
-       struct tcm_qla2xxx_tpg *base_tpg = container_of(work,
-                               struct tcm_qla2xxx_tpg, tpg_base_work);
-       struct se_portal_group *se_tpg = &base_tpg->se_tpg;
-       struct scsi_qla_host *base_vha = base_tpg->lport->qla_vha;
-
-       if (!qlt_stop_phase1(base_vha->vha_tgt.qla_tgt)) {
-               atomic_set(&base_tpg->lport_tpg_enabled, 0);
-               target_undepend_item(&se_tpg->tpg_group.cg_item);
-       }
-       complete(&base_tpg->tpg_base_comp);
-}
-
 static ssize_t tcm_qla2xxx_tpg_enable_store(struct config_item *item,
                const char *page, size_t count)
 {
        struct se_portal_group *se_tpg = to_tpg(item);
+       struct se_wwn *se_wwn = se_tpg->se_tpg_wwn;
+       struct tcm_qla2xxx_lport *lport = container_of(se_wwn,
+                       struct tcm_qla2xxx_lport, lport_wwn);
+       struct scsi_qla_host *vha = lport->qla_vha;
        struct tcm_qla2xxx_tpg *tpg = container_of(se_tpg,
                        struct tcm_qla2xxx_tpg, se_tpg);
        unsigned long op;
@@ -1004,24 +980,16 @@ static ssize_t tcm_qla2xxx_tpg_enable_store(struct config_item *item,
                if (atomic_read(&tpg->lport_tpg_enabled))
                        return -EEXIST;
 
-               INIT_WORK(&tpg->tpg_base_work, tcm_qla2xxx_depend_tpg);
+               atomic_set(&tpg->lport_tpg_enabled, 1);
+               qlt_enable_vha(vha);
        } else {
                if (!atomic_read(&tpg->lport_tpg_enabled))
                        return count;
 
-               INIT_WORK(&tpg->tpg_base_work, tcm_qla2xxx_undepend_tpg);
+               atomic_set(&tpg->lport_tpg_enabled, 0);
+               qlt_stop_phase1(vha->vha_tgt.qla_tgt);
        }
-       init_completion(&tpg->tpg_base_comp);
-       schedule_work(&tpg->tpg_base_work);
-       wait_for_completion(&tpg->tpg_base_comp);
 
-       if (op) {
-               if (!atomic_read(&tpg->lport_tpg_enabled))
-                       return -ENODEV;
-       } else {
-               if (atomic_read(&tpg->lport_tpg_enabled))
-                       return -EPERM;
-       }
        return count;
 }
 

diff --git a/drivers/scsi/qla2xxx/tcm_qla2xxx.h b/drivers/scsi/qla2xxx/tcm_qla2xxx.h
index 7550ba2831c36a890f26312ef1404170c3766f78..147cf6c903666b4aa3844a51014fe54e0ef8e1d2 100644 (file)
--- a/drivers/scsi/qla2xxx/tcm_qla2xxx.h
+++ b/drivers/scsi/qla2xxx/tcm_qla2xxx.h
@@ -48,9 +48,6 @@ struct tcm_qla2xxx_tpg {
        struct tcm_qla2xxx_tpg_attrib tpg_attrib;
        /* Returned by tcm_qla2xxx_make_tpg() */
        struct se_portal_group se_tpg;
-       /* Items for dealing with configfs_depend_item */
-       struct completion tpg_base_comp;
-       struct work_struct tpg_base_work;
 };
 
 struct tcm_qla2xxx_fc_loopid {