summaryrefslogtreecommitdiff
path: root/drivers/target/sbp/sbp_target.c
diff options
context:
space:
mode:
authorNicholas Bellinger <nab@linux-iscsi.org>2015-05-19 10:03:07 +0300
committerNicholas Bellinger <nab@linux-iscsi.org>2015-06-01 10:27:38 +0300
commit4cc987eaff9144182cde88d6d132420c28d3f81b (patch)
tree15cf7d432599e1e09446462968ef01c4d10a087e /drivers/target/sbp/sbp_target.c
parentadf653f92f38e80a78bb77e912d49bcc8055330f (diff)
downloadlinux-4cc987eaff9144182cde88d6d132420c28d3f81b.tar.xz
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/sbp/sbp_target.c')
-rw-r--r--drivers/target/sbp/sbp_target.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/target/sbp/sbp_target.c b/drivers/target/sbp/sbp_target.c
index 47fb12fbaf47..28e3adf1eb85 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 */