[PATCH 3/3] drivers: target: tcm_fc: tfc_sess: Pass lockdep expression to RCU lists

Amol Grover
2020-01-10T12:45:23Z

head is traversed with hlist_for_each_entry_rcu
outside an RCU read-side critical section but under the
protection of ft_lport_lock.

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

Add macro for the corresponding lockdep expression to make the code
clean and concise.

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
drivers/target/tcm_fc/tfc_sess.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/target/tcm_fc/tfc_sess.c b/drivers/target/tcm_fc/tfc_sess.c
index 4fd6a1de947c..8e9598010fb9 100644
--- a/drivers/target/tcm_fc/tfc_sess.c
+++ b/drivers/target/tcm_fc/tfc_sess.c
@@ -32,6 +32,9 @@
(lport)->host->host_no, \
(lport)->port_id, ##args )

+#define ft_lport_lock_held() \
+ lockdep_is_held(&ft_lport_lock)
+
static void ft_sess_delete_all(struct ft_tport *);

/*
@@ -45,7 +48,7 @@ static struct ft_tport *ft_tport_get(struct fc_lport *lport)
int i;

tport = rcu_dereference_protected(lport->prov[FC_TYPE_FCP],
- lockdep_is_held(&ft_lport_lock));
+ ft_lport_lock_held());
if (tport && tport->tpg)
return tport;

@@ -170,7 +173,7 @@ static struct ft_sess *ft_sess_get(struct fc_lport *lport, u32 port_id)
}

head = &tport->hash[ft_sess_hash(port_id)];
- hlist_for_each_entry_rcu(sess, head, hash) {
+ hlist_for_each_entry_rcu(sess, head, hash, ft_lport_lock_held()) {
if (sess->port_id == port_id) {
kref_get(&sess->kref);
rcu_read_unlock();
@@ -215,7 +218,7 @@ static struct ft_sess *ft_sess_create(struct ft_tport *tport, u32 port_id,
ft_format_wwn(&initiatorname[0], TRANSPORT_IQN_LEN, rdata->ids.port_name);

head = &tport->hash[ft_sess_hash(port_id)];
- hlist_for_each_entry_rcu(sess, head, hash)
+ hlist_for_each_entry_rcu(sess, head, hash, ft_lport_lock_held())
if (sess->port_id == port_id)
return sess;

@@ -264,7 +267,7 @@ static struct ft_sess *ft_sess_delete(struct ft_tport *tport, u32 port_id)
struct ft_sess *sess;

head = &tport->hash[ft_sess_hash(port_id)];
- hlist_for_each_entry_rcu(sess, head, hash) {
+ hlist_for_each_entry_rcu(sess, head, hash, ft_lport_lock_held()) {
if (sess->port_id == port_id) {
ft_sess_unhash(sess);
return sess;
@@ -291,7 +294,7 @@ static void ft_sess_delete_all(struct ft_tport *tport)

for (head = tport->hash;
head < &tport->hash[FT_SESS_HASH_SIZE]; head++) {
- hlist_for_each_entry_rcu(sess, head, hash) {
+ hlist_for_each_entry_rcu(sess, head, hash, ft_lport_lock_held()) {
ft_sess_unhash(sess);
ft_close_sess(sess); /* release from table */
}
@@ -454,7 +457,7 @@ static void ft_prlo(struct fc_rport_priv *rdata)

mutex_lock(&ft_lport_lock);
tport = rcu_dereference_protected(rdata->local_port->prov[FC_TYPE_FCP],
- lockdep_is_held(&ft_lport_lock));
+ ft_lport_lock_held());

if (!tport) {
mutex_unlock(&ft_lport_lock);
--
2.24.1