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Date: Fri, 22 May 2015 07:06:55 +0000
From: "Nicholas A. Bellinger" <nab@...erainc.com>
To: target-devel <target-devel@...r.kernel.org>
Cc: linux-scsi <linux-scsi@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Christoph Hellwig <hch@....de>,
Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH 2/4] target: Drop lun_sep_lock for se_lun->lun_se_dev RCU usage
From: Nicholas Bellinger <nab@...ux-iscsi.org>
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.
Also, convert se_lun->lun_stats to use atomic_long_t within the
target_complete_ok_work() completion callback.
Reported-by: Christoph Hellwig <hch@....de>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
---
drivers/target/target_core_device.c | 1 -
drivers/target/target_core_stat.c | 65 +++++++++++++++++-----------------
drivers/target/target_core_tpg.c | 8 ++---
drivers/target/target_core_transport.c | 22 ++++--------
include/target/target_core_base.h | 9 +++--
5 files changed, 46 insertions(+), 59 deletions(-)
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 31133ce..1d98033 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -792,7 +792,6 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
xcopy_lun = &dev->xcopy_lun;
xcopy_lun->lun_se_dev = dev;
- spin_lock_init(&xcopy_lun->lun_sep_lock);
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_stat.c b/drivers/target/target_core_stat.c
index 5127c67..d38a18e 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);
+ rcu_read_lock();
dev = lun->lun_se_dev;
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", dev->se_hba->hba_index);
- spin_unlock(&lun->lun_sep_lock);
+ 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);
+ rcu_read_lock();
dev = 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);
@@ -576,10 +576,10 @@ static ssize_t target_stat_scsi_port_show_attr_indx(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret = -ENODEV;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
if (lun->lun_se_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);
@@ -591,13 +591,13 @@ static ssize_t target_stat_scsi_port_show_attr_role(
struct se_device *dev;
ssize_t ret = -ENODEV;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
dev = 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);
@@ -608,12 +608,12 @@ static ssize_t target_stat_scsi_port_show_attr_busy_count(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret = -ENODEV;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
if (lun->lun_se_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);
@@ -664,11 +664,11 @@ 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);
+ rcu_read_lock();
dev = lun->lun_se_dev;
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", dev->se_hba->hba_index);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TGT_PORT_ATTR_RO(inst);
@@ -680,11 +680,11 @@ 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);
+ rcu_read_lock();
dev = 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);
@@ -695,10 +695,10 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_indx(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret = -ENODEV;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
if (lun->lun_se_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);
@@ -709,13 +709,13 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_name(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret = -ENODEV;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
if (lun->lun_se_dev) {
ret = snprintf(page, PAGE_SIZE, "%sPort#%u\n",
lun->lun_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);
@@ -738,9 +738,10 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_in_cmds(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret;
- spin_lock(&lun->lun_sep_lock);
- ret = snprintf(page, PAGE_SIZE, "%llu\n", lun->lun_stats.cmd_pdus);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_lock();
+ ret = snprintf(page, PAGE_SIZE, "%lu\n",
+ atomic_long_read(&lun->lun_stats.cmd_pdus));
+ rcu_read_unlock();
return ret;
}
@@ -752,10 +753,10 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_write_mbytes(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
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);
@@ -766,10 +767,10 @@ static ssize_t target_stat_scsi_tgt_port_show_attr_read_mbytes(
struct se_lun *lun = container_of(pgrps, struct se_lun, port_stat_grps);
ssize_t ret;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
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);
@@ -834,11 +835,11 @@ static ssize_t target_stat_scsi_transport_show_attr_inst(
struct se_device *dev;
ssize_t ret = -ENODEV;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
dev = lun->lun_se_dev;
if (dev)
ret = snprintf(page, PAGE_SIZE, "%u\n", dev->se_hba->hba_index);
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return ret;
}
DEV_STAT_SCSI_TRANSPORT_ATTR_RO(inst);
@@ -874,10 +875,10 @@ static ssize_t target_stat_scsi_transport_show_attr_dev_name(
struct t10_wwn *wwn;
ssize_t ret;
- spin_lock(&lun->lun_sep_lock);
+ rcu_read_lock();
dev = lun->lun_se_dev;
if (!dev) {
- spin_unlock(&lun->lun_sep_lock);
+ rcu_read_unlock();
return -ENODEV;
}
wwn = &dev->t10_wwn;
@@ -886,7 +887,7 @@ static ssize_t target_stat_scsi_transport_show_attr_dev_name(
tpg->se_tpg_tfo->tpg_get_wwn(tpg),
(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 8764f1c..f60b74e 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -601,7 +601,6 @@ struct se_lun *core_tpg_alloc_lun(
lun->lun_link_magic = SE_LUN_LINK_MAGIC;
lun->lun_status = TRANSPORT_LUN_STATUS_FREE;
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);
@@ -638,10 +637,7 @@ int core_tpg_add_lun(
target_attach_tg_pt_gp(lun, dev->t10_alua.default_tg_pt_gp);
mutex_lock(&tpg->tpg_lun_mutex);
-
- spin_lock(&lun->lun_sep_lock);
- lun->lun_se_dev = dev;
- spin_unlock(&lun->lun_sep_lock);
+ rcu_assign_pointer(lun->lun_se_dev, dev);
spin_lock(&dev->se_port_lock);
dev->export_count++;
@@ -683,7 +679,7 @@ void core_tpg_remove_lun(
dev->export_count--;
spin_unlock(&dev->se_port_lock);
- lun->lun_se_dev = NULL;
+ rcu_assign_pointer(lun->lun_se_dev, NULL);
}
lun->lun_status = TRANSPORT_LUN_STATUS_FREE;
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 1f9688a..2ccaeff 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);
@@ -2061,10 +2058,8 @@ 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
@@ -2087,17 +2082,14 @@ 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/include/target/target_core_base.h b/include/target/target_core_base.h
index b3df83e..6cd1452 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -695,9 +695,9 @@ struct se_port_stat_grps {
};
struct scsi_port_stats {
- u64 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 {
@@ -711,8 +711,7 @@ struct se_lun {
u32 lun_flags;
u32 unpacked_lun;
atomic_t lun_acl_count;
- spinlock_t lun_sep_lock;
- struct se_device *lun_se_dev;
+ struct se_device __rcu *lun_se_dev;
struct list_head lun_deve_list;
spinlock_t lun_deve_lock;
--
1.9.1
--
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