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target/pr: Use atomic bitop for se_dev_entry->deve_flags reservation check 

This patch converts the core_scsi3_pr_seq_non_holder() check for non
reservation holding registrations to use an atomic bitop in ->deve_flags
to determine if a registration is currently active.

It also includes associated a set_bit() in __core_scsi3_add_registration()
and clear_bit() in __core_scsi3_free_registration(), if se_dev_entry still
exists, and has not already been released via se_dev_entry shutdown path
in core_disable_device_list_for_node().

Also, clear_bit in core_disable_device_list_for_node as well to ensure
the read-critical path in core_scsi3_pr_seq_non_holder() picks up the
new state, preceeding the final kfree_rcu() call.

Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger 2015-03-25 01:02:57 -07:00
parent 29a05deebf
commit 80bfdfa924
3 changed files with 42 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/target/target_core_device.c
View File

@ -413,6 +413,7 @@ void core_disable_device_list_for_node(
core_scsi3_ua_release_all(orig);
hlist_del_rcu(&orig->link);
clear_bit(DEF_PR_REG_ACTIVE, &orig->deve_flags);
rcu_assign_pointer(orig->se_lun, NULL);
rcu_assign_pointer(orig->se_lun_acl, NULL);
orig->lun_flags = 0;

58
drivers/target/target_core_pr.c
View File

@ -327,9 +327,13 @@ static int core_scsi3_pr_seq_non_holder(
int we = 0; /* Write Exclusive */
int legacy = 0; /* Act like a legacy device and return
* RESERVATION CONFLICT on some CDBs */
bool registered = false;
rcu_read_lock();
se_deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);
if (se_deve)
registered = test_bit(DEF_PR_REG_ACTIVE, &se_deve->deve_flags);
rcu_read_unlock();
/*
* Determine if the registration should be ignored due to
* non-matching ISIDs in target_scsi3_pr_reservation_check().
@ -346,7 +350,7 @@ static int core_scsi3_pr_seq_non_holder(
* Some commands are only allowed for the persistent reservation
* holder.
*/
if ((se_deve->def_pr_registered) && !(ignore_reg))
if ((registered) && !(ignore_reg))
registered_nexus = 1;
break;
case PR_TYPE_WRITE_EXCLUSIVE_REGONLY:
@ -356,7 +360,7 @@ static int core_scsi3_pr_seq_non_holder(
* Some commands are only allowed for registered I_T Nexuses.
*/
reg_only = 1;
if ((se_deve->def_pr_registered) && !(ignore_reg))
if ((registered) && !(ignore_reg))
registered_nexus = 1;
break;
case PR_TYPE_WRITE_EXCLUSIVE_ALLREG:
@ -366,14 +370,12 @@ static int core_scsi3_pr_seq_non_holder(
* Each registered I_T Nexus is a reservation holder.
*/
all_reg = 1;
if ((se_deve->def_pr_registered) && !(ignore_reg))
if ((registered) && !(ignore_reg))
registered_nexus = 1;
break;
default:
rcu_read_unlock();
return -EINVAL;
}
rcu_read_unlock();
/*
* Referenced from spc4r17 table 45 for *NON* PR holder access
*/
@ -1009,10 +1011,6 @@ static void __core_scsi3_dump_registration(
pr_reg->pr_reg_aptpl);
}
/*
* this function can be called with struct se_device->dev_reservation_lock
* when register_move = 1
*/
static void __core_scsi3_add_registration(
struct se_device *dev,
struct se_node_acl *nacl,
@ -1023,6 +1021,7 @@ static void __core_scsi3_add_registration(
const struct target_core_fabric_ops *tfo = nacl->se_tpg->se_tpg_tfo;
struct t10_pr_registration *pr_reg_tmp, *pr_reg_tmp_safe;
struct t10_reservation *pr_tmpl = &dev->t10_pr;
struct se_dev_entry *deve;
/*
* Increment PRgeneration counter for struct se_device upon a successful
@ -1039,10 +1038,16 @@ static void __core_scsi3_add_registration(
spin_lock(&pr_tmpl->registration_lock);
list_add_tail(&pr_reg->pr_reg_list, &pr_tmpl->registration_list);
pr_reg->pr_reg_deve->def_pr_registered = 1;
__core_scsi3_dump_registration(tfo, dev, nacl, pr_reg, register_type);
spin_unlock(&pr_tmpl->registration_lock);
rcu_read_lock();
deve = pr_reg->pr_reg_deve;
if (deve)
set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags);
rcu_read_unlock();
/*
* Skip extra processing for ALL_TG_PT=0 or REGISTER_AND_MOVE.
*/
@ -1054,6 +1059,8 @@ static void __core_scsi3_add_registration(
*/
list_for_each_entry_safe(pr_reg_tmp, pr_reg_tmp_safe,
&pr_reg->pr_reg_atp_list, pr_reg_atp_mem_list) {
struct se_node_acl *nacl_tmp = pr_reg_tmp->pr_reg_nacl;
list_del(&pr_reg_tmp->pr_reg_atp_mem_list);
pr_reg_tmp->pr_res_generation = core_scsi3_pr_generation(dev);
@ -1061,12 +1068,17 @@ static void __core_scsi3_add_registration(
spin_lock(&pr_tmpl->registration_lock);
list_add_tail(&pr_reg_tmp->pr_reg_list,
&pr_tmpl->registration_list);
pr_reg_tmp->pr_reg_deve->def_pr_registered = 1;
__core_scsi3_dump_registration(tfo, dev,
pr_reg_tmp->pr_reg_nacl, pr_reg_tmp,
register_type);
__core_scsi3_dump_registration(tfo, dev, nacl_tmp, pr_reg_tmp,
register_type);
spin_unlock(&pr_tmpl->registration_lock);
rcu_read_lock();
deve = pr_reg_tmp->pr_reg_deve;
if (deve)
set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags);
rcu_read_unlock();
/*
* Drop configfs group dependency reference from
* __core_scsi3_alloc_registration()
@ -1242,13 +1254,13 @@ static void __core_scsi3_free_registration(
const struct target_core_fabric_ops *tfo =
pr_reg->pr_reg_nacl->se_tpg->se_tpg_tfo;
struct t10_reservation *pr_tmpl = &dev->t10_pr;
struct se_node_acl *nacl = pr_reg->pr_reg_nacl;
struct se_dev_entry *deve;
char i_buf[PR_REG_ISID_ID_LEN];
memset(i_buf, 0, PR_REG_ISID_ID_LEN);
core_pr_dump_initiator_port(pr_reg, i_buf, PR_REG_ISID_ID_LEN);
pr_reg->pr_reg_deve->def_pr_registered = 0;
pr_reg->pr_reg_deve->pr_res_key = 0;
if (!list_empty(&pr_reg->pr_reg_list))
list_del(&pr_reg->pr_reg_list);
/*
@ -1257,6 +1269,8 @@ static void __core_scsi3_free_registration(
*/
if (dec_holders)
core_scsi3_put_pr_reg(pr_reg);
spin_unlock(&pr_tmpl->registration_lock);
/*
* Wait until all reference from any other I_T nexuses for this
* *pr_reg have been released. Because list_del() is called above,
@ -1264,13 +1278,18 @@ static void __core_scsi3_free_registration(
* count back to zero, and we release *pr_reg.
*/
while (atomic_read(&pr_reg->pr_res_holders) != 0) {
spin_unlock(&pr_tmpl->registration_lock);
pr_debug("SPC-3 PR [%s] waiting for pr_res_holders\n",
tfo->get_fabric_name());
cpu_relax();
spin_lock(&pr_tmpl->registration_lock);
}
rcu_read_lock();
deve = target_nacl_find_deve(nacl, pr_reg->pr_res_mapped_lun);
if (deve)
clear_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags);
rcu_read_unlock();
spin_lock(&pr_tmpl->registration_lock);
pr_debug("SPC-3 PR [%s] Service Action: UNREGISTER Initiator"
" Node: %s%s\n", tfo->get_fabric_name(),
pr_reg->pr_reg_nacl->initiatorname,
@ -3421,13 +3440,14 @@ core_scsi3_emulate_pro_register_and_move(struct se_cmd *cmd, u64 res_key,
dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
iport_ptr);
if (!dest_pr_reg) {
spin_unlock(&dev->dev_reservation_lock);
if (core_scsi3_alloc_registration(cmd->se_dev,
dest_node_acl, dest_se_deve, iport_ptr,
sa_res_key, 0, aptpl, 2, 1)) {
spin_unlock(&dev->dev_reservation_lock);
ret = TCM_INVALID_PARAMETER_LIST;
goto out;
}
spin_lock(&dev->dev_reservation_lock);
dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
iport_ptr);
new_reg = 1;

3
include/target/target_core_base.h
View File

@ -638,7 +638,6 @@ struct se_lun_acl {
};
struct se_dev_entry {
bool def_pr_registered;
/* See transport_lunflags_table */
u32 lun_flags;
u32 mapped_lun;
@ -655,6 +654,8 @@ struct se_dev_entry {
struct se_lun_acl __rcu *se_lun_acl;
spinlock_t ua_lock;
struct se_lun __rcu *se_lun;
#define DEF_PR_REG_ACTIVE 1
unsigned long deve_flags;
struct list_head alua_port_list;
struct list_head ua_list;
struct hlist_node link;