[PATCH v3 1/3] drivers: target: target_core_device: Pass lockdep expression to RCU lists

Amol Grover
2020-01-17T13:40:19Z

nacl->lun_entry_hlist is traversed with hlist_for_each_entry_rcu
outside an RCU read-side critical section but under the
protection of nacl->lun_entry_mutex.

Hence, add the corresponding lockdep expression to the list traversal
primitive to silence false-positive lockdep warnings, and
harden RCU lists.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
v3:
- Remove rcu_read_lock_held() from lockdep expression since it is
implicitly checked for.
- Remove unintended macro usage.

v2:
- Fix sparse error
CHECK: Alignment should match open parenthesis

drivers/target/target_core_device.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 2d19f0e332b0..306c626183d5 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -247,7 +247,8 @@ void core_free_device_list_for_node(
struct se_dev_entry *deve;

mutex_lock(&nacl->lun_entry_mutex);
- hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
+ hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link,
+ lockdep_is_held(&nacl->lun_entry_mutex)) {
struct se_lun *lun = rcu_dereference_check(deve->se_lun,
lockdep_is_held(&nacl->lun_entry_mutex));
core_disable_device_list_for_node(lun, deve, nacl, tpg);
@@ -276,7 +277,8 @@ struct se_dev_entry *target_nacl_find_deve(struct se_node_acl *nacl, u64 mapped_
{
struct se_dev_entry *deve;

- hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link)
+ hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link,
+ lockdep_is_held(&nacl->lun_entry_mutex))
if (deve->mapped_lun == mapped_lun)
return deve;

@@ -460,7 +462,8 @@ void core_clear_lun_from_tpg(struct se_lun *lun, struct se_portal_group *tpg)
list_for_each_entry(nacl, &tpg->acl_node_list, acl_list) {

mutex_lock(&nacl->lun_entry_mutex);
- hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link) {
+ hlist_for_each_entry_rcu(deve, &nacl->lun_entry_hlist, link,
+ lockdep_is_held(&nacl->lun_entry_mutex)) {
struct se_lun *tmp_lun = rcu_dereference_check(deve->se_lun,
lockdep_is_held(&nacl->lun_entry_mutex));

--
2.24.1