target: Drop lun_sep_lock for se_lun->lun_se_dev RCU usage

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@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Boot <bootc@bootc.net>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/sbp/sbp_target.c b/drivers/target/sbp/sbp_target.c
index 47fb12fbaf47c02e23d3f303dd5d5aa00ce36521..28e3adf1eb853b121617aeb9d276a4adeb0b7071 100644 (file)
--- 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 1109c2833fe69ca85a5130dafb397bca870cedfc..0a0087311cfb33e6b84035421a12bbdcd22c3d86 100644 (file)
--- 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 8485e9a789fc5253b44da876db6e384fef994a98..3baa6cd7fded2223d1fe76d8fbae8d681474f528 100644 (file)
--- 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);
@@ -389,6 +394,11 @@ void core_disable_device_list_for_node(
        struct se_node_acl *nacl,
        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
@@ -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 948b61f59a552698e4d6f82e7bf5dcf043306039..238e3a256d04cbd035466ddcf96aefe95ed511a0 100644 (file)
--- 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 6d473825256446469551e1f5c9a35a45dcd16992..ae8ad2da6632f426b7dc39da0b72e659aec16285 100644 (file)
--- 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 afb87a8d5668cadbf82141196a07331430d63da8..c673980ded04454c61f21af4614b5722df38e77d 100644 (file)
--- 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 55dd73e7f213a984ad5ce4f227aaa9c0594cab1b..e98432705f39597edcbce3abbfd6270f0e5daa3c 100644 (file)
--- 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 34d8292a44327dd8969efcbb18f5cee4c5e92d5f..a2b377e06cfaae9a2daa6d75cbbce67b7b31ba3d 100644 (file)
--- 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 8e080efb018800618405acf8dd99b865f162ded6..79c7852423754cf558249aa700044e75fd3bf9ed 100644 (file)
--- 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 499b1399035acdefe2a8a2c255c46d293536ff9a..5b30940ccaf21760293384490f2c4218878fcce4 100644 (file)
--- 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 ef6fdd8a47c409a190f9ecdc5249d6a0394cee31..d8a59122fe3b188f7788eac4557c4fd14e4aeadb 100644 (file)
--- 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 aebaad55e23f919cb342a34312682bd0ee83cb6d..949e6165ef8a758b1d0aab4c80150d6c92bc501c 100644 (file)
--- 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 1927dd5947a78932bf75a4322261bfe0bbe5b2be..b82a989a4d3bf86765bc43bc7521043654b78dbd 100644 (file)
--- 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 {