[PATCH 06/12] target/pr: Convert se_dev_entry to kref for RCU

From: Nicholas A. Bellinger
Date: Tue May 12 2015 - 05:33:53 EST

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

This patch converts se_dev_entry->pr_ref_count access to use modern
struct kref counting.

It updates core_enable_device_list_for_node() to kref_init() when se_dev_entry
is being enabled, and updates core_disable_device_list_for_node() to kref_put()
and blocks on ->pr_comp waiting for outstanding PR references to drop.

Also, go ahead and convert core_get_se_deve_from_rtpi() code to use pr_kref
for RELATIVE TARGET PORT IDENTIFIER lookup.

Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_device.c | 27 ++++++++----
drivers/target/target_core_internal.h | 1 +
drivers/target/target_core_pr.c | 78 ++++++++++++++++++++++-------------
include/target/target_core_base.h | 4 +-
4 files changed, 71 insertions(+), 39 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 36e7d13..911758b 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -203,7 +203,7 @@ EXPORT_SYMBOL(transport_lookup_tmr_lun);

/*
* This function is called from core_scsi3_emulate_pro_register_and_move()
- * and core_scsi3_decode_spec_i_port(), and will increment &deve->pr_ref_count
+ * and core_scsi3_decode_spec_i_port(), and will increment &deve->pr_kref
* when a matching rtpi is found.
*/
struct se_dev_entry *core_get_se_deve_from_rtpi(
@@ -237,7 +237,7 @@ struct se_dev_entry *core_get_se_deve_from_rtpi(
if (port->sep_rtpi != rtpi)
continue;

- atomic_inc_mb(&deve->pr_ref_count);
+ kref_get(&deve->pr_kref);
rcu_read_unlock();

return deve;
@@ -323,6 +323,13 @@ struct se_dev_entry *target_nacl_find_deve(struct se_node_acl *nacl, u32 mapped_
}
EXPORT_SYMBOL(target_nacl_find_deve);

+void target_pr_kref_release(struct kref *kref)
+{
+ struct se_dev_entry *deve = container_of(kref, struct se_dev_entry,
+ pr_kref);
+ complete(&deve->pr_comp);
+}
+
/* core_enable_device_list_for_node():
*
*
@@ -353,6 +360,9 @@ int core_enable_device_list_for_node(
new->mapped_lun = mapped_lun;
new->lun_flags |= TRANSPORT_LUNFLAGS_INITIATOR_ACCESS;

+ kref_init(&new->pr_kref);
+ init_completion(&new->pr_comp);
+
if (lun_access & TRANSPORT_LUNFLAGS_READ_WRITE)
new->lun_flags |= TRANSPORT_LUNFLAGS_READ_WRITE;
else
@@ -377,6 +387,9 @@ int core_enable_device_list_for_node(
list_add_tail(&new->alua_port_list, &port->sep_alua_list);
spin_unlock_bh(&port->sep_alua_lock);

+ kref_put(&orig->pr_kref, target_pr_kref_release);
+ wait_for_completion(&orig->pr_comp);
+
call_rcu(&orig->rcu_head, target_nacl_deve_callrcu);
return 0;
}
@@ -432,13 +445,6 @@ int core_disable_device_list_for_node(
list_del(&orig->alua_port_list);
spin_unlock_bh(&port->sep_alua_lock);
/*
- * Wait for any in process SPEC_I_PT=1 or REGISTER_AND_MOVE
- * PR operation to complete.
- */
- while (atomic_read(&orig->pr_ref_count) != 0)
- cpu_relax();
-
- /*
* Disable struct se_dev_entry LUN ACL mapping
*/
core_scsi3_ua_release_all(orig);
@@ -450,6 +456,9 @@ int core_disable_device_list_for_node(
hlist_del_rcu(&orig->link);
mutex_unlock(&nacl->lun_entry_mutex);

+ kref_put(&orig->pr_kref, target_pr_kref_release);
+ wait_for_completion(&orig->pr_comp);
+
/*
* Fire off RCU callback to wait for any in process SPEC_I_PT=1
* or REGISTER_AND_MOVE PR operation to complete.
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index 9c4bce0..f57bb61 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -9,6 +9,7 @@ extern struct mutex g_device_mutex;
extern struct list_head g_device_list;

struct se_dev_entry *core_get_se_deve_from_rtpi(struct se_node_acl *, u16);
+void target_pr_kref_release(struct kref *);
int core_free_device_list_for_node(struct se_node_acl *,
struct se_portal_group *);
void core_update_device_list_access(u32, u32, struct se_node_acl *);
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 721b664..c0b593a 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -48,7 +48,7 @@ struct pr_transport_id_holder {
struct t10_pr_registration *dest_pr_reg;
struct se_portal_group *dest_tpg;
struct se_node_acl *dest_node_acl;
- struct se_dev_entry *dest_se_deve;
+ struct se_dev_entry __rcu *dest_se_deve;
struct list_head dest_list;
};

@@ -232,7 +232,7 @@ target_scsi2_reservation_release(struct se_cmd *cmd)
tpg = sess->se_tpg;
pr_debug("SCSI-2 Released reservation for %s LUN: %u ->"
" MAPPED LUN: %u for %s\n", tpg->se_tpg_tfo->get_fabric_name(),
- cmd->se_lun->unpacked_lun, cmd->se_deve->mapped_lun,
+ cmd->se_lun->unpacked_lun, cmd->orig_fe_lun,
sess->se_node_acl->initiatorname);

out_unlock:
@@ -281,7 +281,7 @@ target_scsi2_reservation_reserve(struct se_cmd *cmd)
dev->dev_reserved_node_acl->initiatorname);
pr_err("Current attempt - LUN: %u -> MAPPED LUN: %u"
" from %s \n", cmd->se_lun->unpacked_lun,
- cmd->se_deve->mapped_lun,
+ cmd->orig_fe_lun,
sess->se_node_acl->initiatorname);
ret = TCM_RESERVATION_CONFLICT;
goto out_unlock;
@@ -295,7 +295,7 @@ target_scsi2_reservation_reserve(struct se_cmd *cmd)
}
pr_debug("SCSI-2 Reserved %s LUN: %u -> MAPPED LUN: %u"
" for %s\n", tpg->se_tpg_tfo->get_fabric_name(),
- cmd->se_lun->unpacked_lun, cmd->se_deve->mapped_lun,
+ cmd->se_lun->unpacked_lun, cmd->orig_fe_lun,
sess->se_node_acl->initiatorname);

out_unlock:
@@ -320,6 +320,7 @@ static int core_scsi3_pr_seq_non_holder(
unsigned char *cdb = cmd->t_task_cdb;
struct se_dev_entry *se_deve;
struct se_session *se_sess = cmd->se_sess;
+ struct se_node_acl *nacl = se_sess->se_node_acl;
int other_cdb = 0, ignore_reg;
int registered_nexus = 0, ret = 1; /* Conflict by default */
int all_reg = 0, reg_only = 0; /* ALL_REG, REG_ONLY */
@@ -327,7 +328,8 @@ static int core_scsi3_pr_seq_non_holder(
int legacy = 0; /* Act like a legacy device and return
* RESERVATION CONFLICT on some CDBs */

- se_deve = se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
+ rcu_read_lock();
+ se_deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);
/*
* Determine if the registration should be ignored due to
* non-matching ISIDs in target_scsi3_pr_reservation_check().
@@ -368,8 +370,10 @@ static int core_scsi3_pr_seq_non_holder(
registered_nexus = 1;
break;
default:
+ rcu_read_unlock();
return -EINVAL;
}
+ rcu_read_unlock();
/*
* Referenced from spc4r17 table 45 for *NON* PR holder access
*/
@@ -735,7 +739,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
if (strcmp(nacl->initiatorname, nacl_tmp->initiatorname))
continue;

- atomic_inc_mb(&deve_tmp->pr_ref_count);
+ kref_get(&deve_tmp->pr_kref);
spin_unlock_bh(&port->sep_alua_lock);
/*
* Grab a configfs group dependency that is released
@@ -748,7 +752,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
pr_err("core_scsi3_lunacl_depend"
"_item() failed\n");
atomic_dec_mb(&port->sep_tg_pt_ref_cnt);
- atomic_dec_mb(&deve_tmp->pr_ref_count);
+ kref_put(&deve_tmp->pr_kref, target_pr_kref_release);
goto out;
}
/*
@@ -763,7 +767,6 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
sa_res_key, all_tg_pt, aptpl);
if (!pr_reg_atp) {
atomic_dec_mb(&port->sep_tg_pt_ref_cnt);
- atomic_dec_mb(&deve_tmp->pr_ref_count);
core_scsi3_lunacl_undepend_item(deve_tmp);
goto out;
}
@@ -896,7 +899,7 @@ static int __core_scsi3_check_aptpl_registration(
struct se_lun *lun,
u32 target_lun,
struct se_node_acl *nacl,
- struct se_dev_entry *deve)
+ u32 mapped_lun)
{
struct t10_pr_registration *pr_reg, *pr_reg_tmp;
struct t10_reservation *pr_tmpl = &dev->t10_pr;
@@ -924,13 +927,12 @@ static int __core_scsi3_check_aptpl_registration(
pr_reg_aptpl_list) {

if (!strcmp(pr_reg->pr_iport, i_port) &&
- (pr_reg->pr_res_mapped_lun == deve->mapped_lun) &&
+ (pr_reg->pr_res_mapped_lun == mapped_lun) &&
!(strcmp(pr_reg->pr_tport, t_port)) &&
(pr_reg->pr_reg_tpgt == tpgt) &&
(pr_reg->pr_aptpl_target_lun == target_lun)) {

pr_reg->pr_reg_nacl = nacl;
- pr_reg->pr_reg_deve = deve;
pr_reg->pr_reg_tg_pt_lun = lun;

list_del(&pr_reg->pr_reg_aptpl_list);
@@ -968,13 +970,12 @@ int core_scsi3_check_aptpl_registration(
struct se_node_acl *nacl,
u32 mapped_lun)
{
- struct se_dev_entry *deve = nacl->device_list[mapped_lun];
-
if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)
return 0;

return __core_scsi3_check_aptpl_registration(dev, tpg, lun,
- lun->unpacked_lun, nacl, deve);
+ lun->unpacked_lun, nacl,
+ mapped_lun);
}

static void __core_scsi3_dump_registration(
@@ -1409,27 +1410,35 @@ static int core_scsi3_lunacl_depend_item(struct se_dev_entry *se_deve)

static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve)
{
- struct se_lun_acl *lun_acl = se_deve->se_lun_acl;
+ struct se_lun_acl *lun_acl;
struct se_node_acl *nacl;
struct se_portal_group *tpg;
+
+ if (!se_deve) {
+ pr_err("core_scsi3_lunacl_undepend_item passed NULL se_deve\n");
+ dump_stack();
+ return;
+ }
/*
* For nacl->dynamic_node_acl=1
*/
+ lun_acl = se_deve->se_lun_acl;
if (!lun_acl) {
- atomic_dec_mb(&se_deve->pr_ref_count);
+ kref_put(&se_deve->pr_kref, target_pr_kref_release);
return;
}
nacl = lun_acl->se_lun_nacl;
tpg = nacl->se_tpg;

target_undepend_item(&lun_acl->se_lun_group.cg_item);
- atomic_dec_mb(&se_deve->pr_ref_count);
+ kref_put(&se_deve->pr_kref, target_pr_kref_release);
}

static sense_reason_t
core_scsi3_decode_spec_i_port(
struct se_cmd *cmd,
struct se_portal_group *tpg,
+ struct se_dev_entry *local_se_deve,
unsigned char *l_isid,
u64 sa_res_key,
int all_tg_pt,
@@ -1440,7 +1449,7 @@ core_scsi3_decode_spec_i_port(
struct se_portal_group *dest_tpg = NULL, *tmp_tpg;
struct se_session *se_sess = cmd->se_sess;
struct se_node_acl *dest_node_acl = NULL;
- struct se_dev_entry *dest_se_deve = NULL, *local_se_deve;
+ struct se_dev_entry __rcu *dest_se_deve = NULL;
struct t10_pr_registration *dest_pr_reg, *local_pr_reg, *pr_reg_e;
struct t10_pr_registration *pr_reg_tmp, *pr_reg_tmp_safe;
LIST_HEAD(tid_dest_list);
@@ -1453,7 +1462,6 @@ core_scsi3_decode_spec_i_port(
int dest_local_nexus;
u32 dest_rtpi = 0;

- local_se_deve = se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
/*
* Allocate a struct pr_transport_id_holder and setup the
* local_node_acl and local_se_deve pointers and add to
@@ -1468,7 +1476,6 @@ core_scsi3_decode_spec_i_port(
INIT_LIST_HEAD(&tidh_new->dest_list);
tidh_new->dest_tpg = tpg;
tidh_new->dest_node_acl = se_sess->se_node_acl;
- tidh_new->dest_se_deve = local_se_deve;

local_pr_reg = __core_scsi3_alloc_registration(cmd->se_dev,
se_sess->se_node_acl, local_se_deve, l_isid,
@@ -1477,6 +1484,7 @@ core_scsi3_decode_spec_i_port(
kfree(tidh_new);
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
+ rcu_assign_pointer(tidh_new->dest_se_deve, local_se_deve);
tidh_new->dest_pr_reg = local_pr_reg;
/*
* The local I_T nexus does not hold any configfs dependances,
@@ -1636,7 +1644,7 @@ core_scsi3_decode_spec_i_port(
if (core_scsi3_lunacl_depend_item(dest_se_deve)) {
pr_err("core_scsi3_lunacl_depend_item()"
" failed\n");
- atomic_dec_mb(&dest_se_deve->pr_ref_count);
+ kref_put(&dest_se_deve->pr_kref, target_pr_kref_release);
core_scsi3_nodeacl_undepend_item(dest_node_acl);
core_scsi3_tpg_undepend_item(dest_tpg);
ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
@@ -1991,6 +1999,7 @@ core_scsi3_emulate_pro_register(struct se_cmd *cmd, u64 res_key, u64 sa_res_key,
bool aptpl, bool all_tg_pt, bool spec_i_pt, enum register_type register_type)
{
struct se_session *se_sess = cmd->se_sess;
+ struct se_node_acl *nacl = se_sess->se_node_acl;
struct se_device *dev = cmd->se_dev;
struct se_dev_entry *se_deve;
struct se_lun *se_lun = cmd->se_lun;
@@ -2006,7 +2015,14 @@ core_scsi3_emulate_pro_register(struct se_cmd *cmd, u64 res_key, u64 sa_res_key,
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}
se_tpg = se_sess->se_tpg;
- se_deve = se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
+
+ rcu_read_lock();
+ se_deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);
+ if (!se_deve) {
+ pr_err("Unable to locate se_deve for PRO-REGISTER\n");
+ rcu_read_unlock();
+ return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+ }

if (se_tpg->se_tpg_tfo->sess_get_initiator_sid) {
memset(&isid_buf[0], 0, PR_REG_ISID_LEN);
@@ -2022,14 +2038,16 @@ core_scsi3_emulate_pro_register(struct se_cmd *cmd, u64 res_key, u64 sa_res_key,
if (res_key) {
pr_warn("SPC-3 PR: Reservation Key non-zero"
" for SA REGISTER, returning CONFLICT\n");
+ rcu_read_unlock();
return TCM_RESERVATION_CONFLICT;
}
/*
* Do nothing but return GOOD status.
*/
- if (!sa_res_key)
+ if (!sa_res_key) {
+ rcu_read_unlock();
return 0;
-
+ }
if (!spec_i_pt) {
/*
* Perform the Service Action REGISTER on the Initiator
@@ -2042,6 +2060,7 @@ core_scsi3_emulate_pro_register(struct se_cmd *cmd, u64 res_key, u64 sa_res_key,
register_type, 0)) {
pr_err("Unable to allocate"
" struct t10_pr_registration\n");
+ rcu_read_unlock();
return TCM_INVALID_PARAMETER_LIST;
}
} else {
@@ -2053,14 +2072,17 @@ core_scsi3_emulate_pro_register(struct se_cmd *cmd, u64 res_key, u64 sa_res_key,
* logic from of core_scsi3_alloc_registration() for
* each TransportID provided SCSI Initiator Port/Device
*/
- ret = core_scsi3_decode_spec_i_port(cmd, se_tpg,
+ ret = core_scsi3_decode_spec_i_port(cmd, se_tpg, se_deve,
isid_ptr, sa_res_key, all_tg_pt, aptpl);
- if (ret != 0)
+ if (ret != 0) {
+ rcu_read_unlock();
return ret;
+ }
}
-
+ rcu_read_unlock();
return core_scsi3_update_and_write_aptpl(dev, aptpl);
}
+ rcu_read_unlock();

/* ok, existing registration */

@@ -3322,7 +3344,7 @@ after_iport_check:

if (core_scsi3_lunacl_depend_item(dest_se_deve)) {
pr_err("core_scsi3_lunacl_depend_item() failed\n");
- atomic_dec_mb(&dest_se_deve->pr_ref_count);
+ kref_put(&dest_se_deve->pr_kref, target_pr_kref_release);
dest_se_deve = NULL;
ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
goto out;
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 3057eff..1b06d27 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -585,7 +585,6 @@ struct se_node_acl {
/* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
atomic_t acl_pr_ref_count;
struct hlist_head lun_entry_hlist;
- struct se_dev_entry **device_list;
struct se_session *nacl_sess;
struct se_portal_group *se_tpg;
struct mutex lun_entry_mutex;
@@ -653,7 +652,8 @@ struct se_dev_entry {
u64 write_bytes;
atomic_t ua_count;
/* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
- atomic_t pr_ref_count;
+ struct kref pr_kref;
+ struct completion pr_comp;
struct se_node_acl *se_node_acl;
struct se_lun_acl __rcu *se_lun_acl;
spinlock_t ua_lock;
--
1.9.1

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