drivers: char: ipmi: ipmi_msghandler: Pass lockdep expression to RCU lists

intf->cmd_rcvrs is traversed with list_for_each_entry_rcu
outside an RCU read-side critical section but under the
protection of intf->cmd_rcvrs_mutex.

ipmi_interfaces is traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of ipmi_interfaces_mutex.

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>
Message-Id: <20200117132521.31020-1-frextrite@gmail.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index cad9563f8f485b6db8a1b93110d2cda970b49fe3..64ba16dcb681bbcc388deacbc87b8ea902a02f17 100644 (file)
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -618,6 +618,8 @@ static DEFINE_MUTEX(ipmidriver_mutex);
 
 static LIST_HEAD(ipmi_interfaces);
 static DEFINE_MUTEX(ipmi_interfaces_mutex);
+#define ipmi_interfaces_mutex_held() \
+       lockdep_is_held(&ipmi_interfaces_mutex)
 static struct srcu_struct ipmi_interfaces_srcu;
 
 /*
@@ -1321,7 +1323,8 @@ static void _ipmi_destroy_user(struct ipmi_user *user)
         * synchronize_srcu()) then free everything in that list.
         */
        mutex_lock(&intf->cmd_rcvrs_mutex);
-       list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+       list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
+                               lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
                if (rcvr->user == user) {
                        list_del_rcu(&rcvr->link);
                        rcvr->next = rcvrs;
@@ -1599,7 +1602,8 @@ static struct cmd_rcvr *find_cmd_rcvr(struct ipmi_smi *intf,
 {
        struct cmd_rcvr *rcvr;
 
-       list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+       list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
+                               lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
                                        && (rcvr->chans & (1 << chan)))
                        return rcvr;
@@ -1614,7 +1618,8 @@ static int is_cmd_rcvr_exclusive(struct ipmi_smi *intf,
 {
        struct cmd_rcvr *rcvr;
 
-       list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+       list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link,
+                               lockdep_is_held(&intf->cmd_rcvrs_mutex)) {
                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)
                                        && (rcvr->chans & chans))
                        return 0;
@@ -3450,7 +3455,8 @@ int ipmi_add_smi(struct module         *owner,
        /* Look for a hole in the numbers. */
        i = 0;
        link = &ipmi_interfaces;
-       list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
+       list_for_each_entry_rcu(tintf, &ipmi_interfaces, link,
+                               ipmi_interfaces_mutex_held()) {
                if (tintf->intf_num != i) {
                        link = &tintf->link;
                        break;