[PATCH-v3 2/4] target: Drop lun_sep_lock for se_lun->lun_se_dev RCU usage

From: Nicholas A. Bellinger
Date: Mon Jun 01 2015 - 04:25:26 EST

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

With se_port and t10_alua_tg_pt_gp_member being absored into se_lun,
there is no need for an extra lock to protect se_lun->lun_se_dev
assignment.

This patch also converts backend drivers to use call_rcu() release
to allow any se_device readers to complete. The call_rcu() instead
of kfree_rcu() is required here because se_device is embedded into
the backend driver specific structure.

Also, convert se_lun->lun_stats to use atomic_long_t within the
target_complete_ok_work() completion callback, and add FIXME for
transport_lookup_tmr_lun() with se_lun->lun_ref.

Finally, update sbp_update_unit_directory() special case usage with
proper rcu_dereference_raw() and configfs symlink comment.

Reported-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Chris Boot <bootc@xxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/sbp/sbp_target.c | 7 +-
drivers/target/target_core_alua.c | 12 +++-
drivers/target/target_core_device.c | 47 ++++++++-----
drivers/target/target_core_file.c | 11 ++-
drivers/target/target_core_iblock.c | 10 ++-
drivers/target/target_core_pscsi.c | 11 ++-
drivers/target/target_core_rd.c | 10 ++-
drivers/target/target_core_spc.c | 2 +-
drivers/target/target_core_stat.c | 123 +++++++++++++++++----------------
drivers/target/target_core_tpg.c | 16 ++---
drivers/target/target_core_transport.c | 20 ++----
drivers/target/target_core_user.c | 11 ++-
include/target/target_core_base.h | 10 +--
13 files changed, 175 insertions(+), 115 deletions(-)

diff --git a/drivers/target/sbp/sbp_target.c b/drivers/target/sbp/sbp_target.c
index 47fb12f..28e3adf 100644
--- a/drivers/target/sbp/sbp_target.c
+++ b/drivers/target/sbp/sbp_target.c
@@ -1905,8 +1905,11 @@ static int sbp_update_unit_directory(struct sbp_tport *tport)
hlist_for_each_entry_rcu(lun, &tport->tpg->se_tpg.tpg_lun_hlist, link) {
struct se_device *dev;
int type;
-
- dev = lun->lun_se_dev;
+ /*
+ * rcu_dereference_raw protected by se_lun->lun_group symlink
+ * reference to se_device->dev_group.
+ */
+ dev = rcu_dereference_raw(lun->lun_se_dev);
type = dev->transport->get_device_type(dev);

/* logical_unit_number */
diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
index 1109c28..0a00873 100644
--- a/drivers/target/target_core_alua.c
+++ b/drivers/target/target_core_alua.c
@@ -1935,7 +1935,11 @@ ssize_t core_alua_store_tg_pt_gp_info(
size_t count)
{
struct se_portal_group *tpg = lun->lun_tpg;
- struct se_device *dev = lun->lun_se_dev;
+ /*
+ * rcu_dereference_raw protected by se_lun->lun_group symlink
+ * reference to se_device->dev_group.
+ */
+ struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
struct t10_alua_tg_pt_gp *tg_pt_gp = NULL, *tg_pt_gp_new = NULL;
unsigned char buf[TG_PT_GROUP_NAME_BUF];
int move = 0;
@@ -2189,7 +2193,11 @@ ssize_t core_alua_store_offline_bit(
const char *page,
size_t count)
{
- struct se_device *dev = lun->lun_se_dev;
+ /*
+ * rcu_dereference_raw protected by se_lun->lun_group symlink
+ * reference to se_device->dev_group.
+ */
+ struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
unsigned long tmp;
int ret;

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 8485e9a..3baa6cd 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -61,7 +61,6 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
struct se_lun *se_lun = NULL;
struct se_session *se_sess = se_cmd->se_sess;
struct se_node_acl *nacl = se_sess->se_node_acl;
- struct se_device *dev;
struct se_dev_entry *deve;

if (unpacked_lun >= TRANSPORT_MAX_LUNS_PER_TPG)
@@ -128,16 +127,21 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
percpu_ref_get(&se_lun->lun_ref);
se_cmd->lun_ref_active = true;
}
+ /*
+ * RCU reference protected by percpu se_lun->lun_ref taken above that
+ * must drop to zero (including initial reference) before this se_lun
+ * pointer can be kfree_rcu() by the final se_lun->lun_group put via
+ * target_core_fabric_configfs.c:target_fabric_port_release
+ */
+ se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);
+ atomic_long_inc(&se_cmd->se_dev->num_cmds);

- /* Directly associate cmd with se_dev */
- se_cmd->se_dev = se_lun->lun_se_dev;
-
- dev = se_lun->lun_se_dev;
- atomic_long_inc(&dev->num_cmds);
if (se_cmd->data_direction == DMA_TO_DEVICE)
- atomic_long_add(se_cmd->data_length, &dev->write_bytes);
+ atomic_long_add(se_cmd->data_length,
+ &se_cmd->se_dev->write_bytes);
else if (se_cmd->data_direction == DMA_FROM_DEVICE)
- atomic_long_add(se_cmd->data_length, &dev->read_bytes);
+ atomic_long_add(se_cmd->data_length,
+ &se_cmd->se_dev->read_bytes);

return 0;
}
@@ -173,10 +177,11 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
unpacked_lun);
return -ENODEV;
}
-
- /* Directly associate cmd with se_dev */
- se_cmd->se_dev = se_lun->lun_se_dev;
- se_tmr->tmr_dev = se_lun->lun_se_dev;
+ /*
+ * XXX: Add percpu se_lun->lun_ref reference count for TMR
+ */
+ se_cmd->se_dev = rcu_dereference_raw(se_lun->lun_se_dev);
+ se_tmr->tmr_dev = rcu_dereference_raw(se_lun->lun_se_dev);

spin_lock_irqsave(&se_tmr->tmr_dev->se_tmr_lock, flags);
list_add_tail(&se_tmr->tmr_list, &se_tmr->tmr_dev->dev_tmr_list);
@@ -390,6 +395,11 @@ void core_disable_device_list_for_node(
struct se_portal_group *tpg)
{
/*
+ * rcu_dereference_raw protected by se_lun->lun_group symlink
+ * reference to se_device->dev_group.
+ */
+ struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
+ /*
* If the MappedLUN entry is being disabled, the entry in
* lun->lun_deve_list must be removed now before clearing the
* struct se_dev_entry pointers below as logic in
@@ -426,7 +436,7 @@ void core_disable_device_list_for_node(

kfree_rcu(orig, rcu_head);

- core_scsi3_free_pr_reg_from_nacl(lun->lun_se_dev, nacl);
+ core_scsi3_free_pr_reg_from_nacl(dev, nacl);
}

/* core_clear_lun_from_tpg():
@@ -629,6 +639,11 @@ int core_dev_add_initiator_node_lun_acl(
u32 lun_access)
{
struct se_node_acl *nacl = lacl->se_lun_nacl;
+ /*
+ * rcu_dereference_raw protected by se_lun->lun_group symlink
+ * reference to se_device->dev_group.
+ */
+ struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);

if (!nacl)
return -EINVAL;
@@ -652,7 +667,7 @@ int core_dev_add_initiator_node_lun_acl(
* Check to see if there are any existing persistent reservation APTPL
* pre-registrations that need to be enabled for this LUN ACL..
*/
- core_scsi3_check_aptpl_registration(lun->lun_se_dev, tpg, lun, nacl,
+ core_scsi3_check_aptpl_registration(dev, tpg, lun, nacl,
lacl->mapped_lun);
return 0;
}
@@ -746,6 +761,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
dev->se_hba = hba;
dev->transport = hba->backend->ops;
dev->prot_length = sizeof(struct se_dif_v1_tuple);
+ dev->hba_index = hba->hba_index;

INIT_LIST_HEAD(&dev->dev_list);
INIT_LIST_HEAD(&dev->dev_sep_list);
@@ -802,8 +818,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;

xcopy_lun = &dev->xcopy_lun;
- xcopy_lun->lun_se_dev = dev;
- spin_lock_init(&xcopy_lun->lun_sep_lock);
+ rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
init_completion(&xcopy_lun->lun_ref_comp);
INIT_LIST_HEAD(&xcopy_lun->lun_deve_list);
INIT_LIST_HEAD(&xcopy_lun->lun_dev_link);
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
index 948b61f..238e3a2 100644
--- a/drivers/target/target_core_file.c
+++ b/drivers/target/target_core_file.c
@@ -241,6 +241,14 @@ fail:
return ret;
}

+static void fd_dev_call_rcu(struct rcu_head *p)
+{
+ struct se_device *dev = container_of(p, struct se_device, rcu_head);
+ struct fd_dev *fd_dev = FD_DEV(dev);
+
+ kfree(fd_dev);
+}
+
static void fd_free_device(struct se_device *dev)
{
struct fd_dev *fd_dev = FD_DEV(dev);
@@ -249,8 +257,7 @@ static void fd_free_device(struct se_device *dev)
filp_close(fd_dev->fd_file, NULL);
fd_dev->fd_file = NULL;
}
-
- kfree(fd_dev);
+ call_rcu(&dev->rcu_head, fd_dev_call_rcu);
}

static int fd_do_rw(struct se_cmd *cmd, struct file *fd,
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 6d47382..ae8ad2d 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -191,6 +191,14 @@ out:
return ret;
}

+static void iblock_dev_call_rcu(struct rcu_head *p)
+{
+ struct se_device *dev = container_of(p, struct se_device, rcu_head);
+ struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
+
+ kfree(ib_dev);
+}
+
static void iblock_free_device(struct se_device *dev)
{
struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
@@ -200,7 +208,7 @@ static void iblock_free_device(struct se_device *dev)
if (ib_dev->ibd_bio_set != NULL)
bioset_free(ib_dev->ibd_bio_set);

- kfree(ib_dev);
+ call_rcu(&dev->rcu_head, iblock_dev_call_rcu);
}

static unsigned long long iblock_emulate_read_cap_with_block_size(
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index afb87a8..c673980 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -579,6 +579,14 @@ static int pscsi_configure_device(struct se_device *dev)
return -ENODEV;
}

+static void pscsi_dev_call_rcu(struct rcu_head *p)
+{
+ struct se_device *dev = container_of(p, struct se_device, rcu_head);
+ struct pscsi_dev_virt *pdv = PSCSI_DEV(dev);
+
+ kfree(pdv);
+}
+
static void pscsi_free_device(struct se_device *dev)
{
struct pscsi_dev_virt *pdv = PSCSI_DEV(dev);
@@ -610,8 +618,7 @@ static void pscsi_free_device(struct se_device *dev)

pdv->pdv_sd = NULL;
}
-
- kfree(pdv);
+ call_rcu(&dev->rcu_head, pscsi_dev_call_rcu);
}

static void pscsi_transport_complete(struct se_cmd *cmd, struct scatterlist *sg,
diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 55dd73e..e984327 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -350,12 +350,20 @@ fail:
return ret;
}

+static void rd_dev_call_rcu(struct rcu_head *p)
+{
+ struct se_device *dev = container_of(p, struct se_device, rcu_head);
+ struct rd_dev *rd_dev = RD_DEV(dev);
+
+ kfree(rd_dev);
+}
+
static void rd_free_device(struct se_device *dev)
{
struct rd_dev *rd_dev = RD_DEV(dev);

rd_release_device_space(rd_dev);
- kfree(rd_dev);
+ call_rcu(&dev->rcu_head, rd_dev_call_rcu);
}

static struct rd_dev_sg_table *rd_get_sg_table(struct rd_dev *rd_dev, u32 page)
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 34d8292..a2b377e 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -692,7 +692,7 @@ spc_emulate_inquiry(struct se_cmd *cmd)
return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
}

- if (dev == tpg->tpg_virt_lun0->lun_se_dev)
+ if (dev == rcu_access_pointer(tpg->tpg_virt_lun0->lun_se_dev))
buf[0] = 0x3f; /* Not connected */
else
buf[0] = dev->transport->get_device_type(dev);
diff --git a/drivers/target/target_core_stat.c b/drivers/target/target_core_stat.c
index 8e080ef..79c7852 100644
--- a/drivers/target/target_core_stat.c
+++ b/drivers/target/target_core_stat.c
@@ -545,11 +545,11 @@ static ssize_t target_stat_scsi_port_show_attr_inst(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
- ret = snprintf(page, PAGE_SIZE, "%u\n", dev->se_hba->hba_index);
- spin_unlock(&lun->lun_sep_lock);
+ ret = snprintf(page, PAGE_SIZE, "%u\n", dev->hba_index);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_PORT_ATTR_RO(inst);
@@ -561,11 +561,11 @@ static ssize_t target_stat_scsi_port_show_attr_dev(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", dev->dev_index);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_PORT_ATTR_RO(dev);
@@ -577,11 +577,11 @@ static ssize_t target_stat_scsi_port_show_attr_indx(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_rtpi);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_PORT_ATTR_RO(indx);
@@ -593,11 +593,11 @@ static ssize_t target_stat_scsi_port_show_attr_role(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%s%u\n", "Device", dev->dev_index);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_PORT_ATTR_RO(role);
@@ -609,13 +609,13 @@ static ssize_t target_stat_scsi_port_show_attr_busy_count(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev) {
/* FIXME: scsiPortBusyStatuses */
ret = snprintf(page, PAGE_SIZE, "%u\n", 0);
}
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_PORT_ATTR_RO(busy_count);
@@ -666,11 +666,11 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_inst(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
- ret = snprintf(page, PAGE_SIZE, "%u\n", dev->se_hba->hba_index);
- spin_unlock(&lun->lun_sep_lock);
+ ret = snprintf(page, PAGE_SIZE, "%u\n", dev->hba_index);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(inst);
@@ -682,11 +682,11 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_dev(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", dev->dev_index);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(dev);
@@ -698,11 +698,11 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_indx(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_rtpi);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(indx);
@@ -715,13 +715,13 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_name(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%sPort#%u\n",
tpg->se_tpg_tfo->get_fabric_name(),
lun->lun_rtpi);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(name);
@@ -734,13 +734,13 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_port_index(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%s%s%d\n",
tpg->se_tpg_tfo->tpg_get_wwn(tpg), "+t+",
tpg->se_tpg_tfo->tpg_get_tag(tpg));
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(port_index);
@@ -752,11 +752,12 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_in_cmds(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
- ret = snprintf(page, PAGE_SIZE, "%u\n", lun->lun_stats.cmd_pdus);
- spin_unlock(&lun->lun_sep_lock);
+ ret = snprintf(page, PAGE_SIZE, "%lu\n",
+ atomic_long_read(&lun->lun_stats.cmd_pdus));
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(in_cmds);
@@ -768,12 +769,12 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_write_mbytes(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n",
- (u32)(lun->lun_stats.rx_data_octets >> 20));
- spin_unlock(&lun->lun_sep_lock);
+ (u32)(atomic_long_read(&lun->lun_stats.rx_data_octets) >> 20));
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(write_mbytes);
@@ -785,12 +786,12 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_read_mbytes(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n",
- (u32)(lun->lun_stats.tx_data_octets >> 20));
- spin_unlock(&lun->lun_sep_lock);
+ (u32)(atomic_long_read(&lun->lun_stats.tx_data_octets) >> 20));
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(read_mbytes);
@@ -802,13 +803,13 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_hs_in_cmds(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev) {
/* FIXME: scsiTgtPortHsInCommands */
ret = snprintf(page, PAGE_SIZE, "%u\n", 0);
}
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(hs_in_cmds);
@@ -865,11 +866,11 @@ static ssize_t target_stat_scsi_transport_show_attr_inst(
struct se_device *dev;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
- ret = snprintf(page, PAGE_SIZE, "%u\n", dev->se_hba->hba_index);
- spin_unlock(&lun->lun_sep_lock);
+ ret = snprintf(page, PAGE_SIZE, "%u\n", dev->hba_index);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TRANSPORT_ATTR_RO(inst);
@@ -882,14 +883,14 @@ static ssize_t target_stat_scsi_transport_show_attr_device(
struct se_portal_group *tpg = lun->lun_tpg;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev) {
/* scsiTransportType */
ret = snprintf(page, PAGE_SIZE, "scsiTransport%s\n",
tpg->se_tpg_tfo->get_fabric_name());
}
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TRANSPORT_ATTR_RO(device);
@@ -902,12 +903,12 @@ static ssize_t target_stat_scsi_transport_show_attr_indx(
struct se_portal_group *tpg = lun->lun_tpg;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n",
tpg->se_tpg_tfo->tpg_get_inst_index(tpg));
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TRANSPORT_ATTR_RO(indx);
@@ -916,13 +917,13 @@ static ssize_t target_stat_scsi_transport_show_attr_dev_name(
struct se_port_stat_grps *pgrps, char *page)
{
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
- struct se_device *dev = lun->lun_se_dev;
+ struct se_device *dev;
struct se_portal_group *tpg = lun->lun_tpg;
struct t10_wwn *wwn;
ssize_t ret = -ENODEV;

- spin_lock(&lun->lun_sep_lock);
- dev = lun->lun_se_dev;
+ rcu_read_lock();
+ dev = rcu_dereference(lun->lun_se_dev);
if (dev) {
wwn = &dev->t10_wwn;
/* scsiTransportDevName */
@@ -931,7 +932,7 @@ static ssize_t target_stat_scsi_transport_show_attr_dev_name(
(strlen(wwn->unit_serial)) ? wwn->unit_serial :
wwn->vendor);
}
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TRANSPORT_ATTR_RO(dev_name);
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 499b139..5b30940 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -102,7 +102,8 @@ void core_tpg_add_node_to_devs(
if (lun_orig && lun != lun_orig)
continue;

- dev = lun->lun_se_dev;
+ dev = rcu_dereference_check(lun->lun_se_dev,
+ lockdep_is_held(&tpg->tpg_lun_mutex));
/*
* By default in LIO-Target $FABRIC_MOD,
* demo_mode_write_protect is ON, or READ_ONLY;
@@ -598,7 +599,6 @@ struct se_lun *core_tpg_alloc_lun(
lun->unpacked_lun = unpacked_lun;
lun->lun_link_magic = SE_LUN_LINK_MAGIC;
atomic_set(&lun->lun_acl_count, 0);
- spin_lock_init(&lun->lun_sep_lock);
init_completion(&lun->lun_ref_comp);
INIT_LIST_HEAD(&lun->lun_deve_list);
INIT_LIST_HEAD(&lun->lun_dev_link);
@@ -636,12 +636,8 @@ int core_tpg_add_lun(

mutex_lock(&tpg->tpg_lun_mutex);

- spin_lock(&lun->lun_sep_lock);
- lun->lun_index = dev->dev_index;
- lun->lun_se_dev = dev;
- spin_unlock(&lun->lun_sep_lock);
-
spin_lock(&dev->se_port_lock);
+ lun->lun_index = dev->dev_index;
rcu_assign_pointer(lun->lun_se_dev, dev);
dev->export_count++;
list_add_tail(&lun->lun_dev_link, &dev->dev_sep_list);
@@ -664,7 +660,11 @@ void core_tpg_remove_lun(
struct se_portal_group *tpg,
struct se_lun *lun)
{
- struct se_device *dev = lun->lun_se_dev;
+ /*
+ * rcu_dereference_raw protected by se_lun->lun_group symlink
+ * reference to se_device->dev_group.
+ */
+ struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);

core_clear_lun_from_tpg(lun, tpg);
transport_clear_lun_ref(lun);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index ef6fdd8..d8a5912 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1261,10 +1261,7 @@ target_setup_cmd_from_cdb(struct se_cmd *cmd, unsigned char *cdb)
return ret;

cmd->se_cmd_flags |= SCF_SUPPORTED_SAM_OPCODE;
-
- spin_lock(&cmd->se_lun->lun_sep_lock);
- cmd->se_lun->lun_stats.cmd_pdus++;
- spin_unlock(&cmd->se_lun->lun_sep_lock);
+ atomic_long_inc(&cmd->se_lun->lun_stats.cmd_pdus);
return 0;
}
EXPORT_SYMBOL(target_setup_cmd_from_cdb);
@@ -2060,9 +2057,8 @@ static void target_complete_ok_work(struct work_struct *work)
queue_rsp:
switch (cmd->data_direction) {
case DMA_FROM_DEVICE:
- spin_lock(&cmd->se_lun->lun_sep_lock);
- cmd->se_lun->lun_stats.tx_data_octets += cmd->data_length;
- spin_unlock(&cmd->se_lun->lun_sep_lock);
+ atomic_long_add(cmd->data_length,
+ &cmd->se_lun->lun_stats.tx_data_octets);
/*
* Perform READ_STRIP of PI using software emulation when
* backend had PI enabled, if the transport will not be
@@ -2085,16 +2081,14 @@ queue_rsp:
goto queue_full;
break;
case DMA_TO_DEVICE:
- spin_lock(&cmd->se_lun->lun_sep_lock);
- cmd->se_lun->lun_stats.rx_data_octets += cmd->data_length;
- spin_unlock(&cmd->se_lun->lun_sep_lock);
+ atomic_long_add(cmd->data_length,
+ &cmd->se_lun->lun_stats.rx_data_octets);
/*
* Check if we need to send READ payload for BIDI-COMMAND
*/
if (cmd->se_cmd_flags & SCF_BIDI) {
- spin_lock(&cmd->se_lun->lun_sep_lock);
- cmd->se_lun->lun_stats.tx_data_octets += cmd->data_length;
- spin_unlock(&cmd->se_lun->lun_sep_lock);
+ atomic_long_add(cmd->data_length,
+ &cmd->se_lun->lun_stats.tx_data_octets);
ret = cmd->se_tfo->queue_data_in(cmd);
if (ret == -EAGAIN || ret == -ENOMEM)
goto queue_full;
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index aebaad5..949e616 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -950,6 +950,14 @@ static int tcmu_check_pending_cmd(int id, void *p, void *data)
return -EINVAL;
}

+static void tcmu_dev_call_rcu(struct rcu_head *p)
+{
+ struct se_device *dev = container_of(p, struct se_device, rcu_head);
+ struct tcmu_dev *udev = TCMU_DEV(dev);
+
+ kfree(udev);
+}
+
static void tcmu_free_device(struct se_device *dev)
{
struct tcmu_dev *udev = TCMU_DEV(dev);
@@ -975,8 +983,7 @@ static void tcmu_free_device(struct se_device *dev)
kfree(udev->uio_info.name);
kfree(udev->name);
}
-
- kfree(udev);
+ call_rcu(&dev->rcu_head, tcmu_dev_call_rcu);
}

enum {
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 1927dd5..b82a989 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -690,9 +690,9 @@ struct se_port_stat_grps {
};

struct scsi_port_stats {
- u32 cmd_pdus;
- u64 tx_data_octets;
- u64 rx_data_octets;
+ atomic_long_t cmd_pdus;
+ atomic_long_t tx_data_octets;
+ atomic_long_t rx_data_octets;
};

struct se_lun {
@@ -705,7 +705,6 @@ struct se_lun {
u32 unpacked_lun;
u32 lun_index;
atomic_t lun_acl_count;
- spinlock_t lun_sep_lock;
struct se_device __rcu *lun_se_dev;

struct list_head lun_deve_list;
@@ -818,6 +817,9 @@ struct se_device {
struct se_lun xcopy_lun;
/* Protection Information */
int prot_length;
+ /* For se_lun->lun_se_dev RCU read-side critical access */
+ u32 hba_index;
+ struct rcu_head rcu_head;
};

struct se_hba {
--
1.9.1

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