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| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-05-19 00:03:07 -0700 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2015-06-01 00:27:38 -0700 |
| commit | 4cc987eaff9144182cde88d6d132420c28d3f81b (patch) | |
| tree | 15cf7d432599e1e09446462968ef01c4d10a087e /drivers/target/target_core_tpg.c | |
| parent | adf653f92f38e80a78bb77e912d49bcc8055330f (diff) | |
| download | linux-stable-4cc987eaff9144182cde88d6d132420c28d3f81b.tar.gz linux-stable-4cc987eaff9144182cde88d6d132420c28d3f81b.tar.bz2 linux-stable-4cc987eaff9144182cde88d6d132420c28d3f81b.zip | |
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>
Diffstat (limited to 'drivers/target/target_core_tpg.c')
| -rw-r--r-- | drivers/target/target_core_tpg.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c index 499b1399035a..5b30940ccaf2 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); |