[PATCH] ipmi: use rcu lock for using command receivers

Use rcu_read_lock for the cmd_rcvrs list, since that was what what
intended, anyway.  This means that all the users of the cmd_rcvrs_lock are
tasks, so the irq disables are no longer required for that lock and it can
become a semaphore.

Signed-off-by: Corey Minyard <minyard@acm.org>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 16 deletions

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 320d7f035bf9..c1d06ba449b6 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -209,7 +209,7 @@ struct ipmi_smi
 
         /* The list of command receivers that are registered for commands
            on this interface. */
-        spinlock_t       cmd_rcvrs_lock;
+        struct semaphore cmd_rcvrs_lock;
         struct list_head cmd_rcvrs;
 
         /* Events that were queues because no one was there to receive
@@ -345,7 +345,6 @@ static void clean_up_interface_data(ipmi_smi_t intf)
 {
         int              i;
         struct cmd_rcvr  *rcvr, *rcvr2;
-        unsigned long    flags;
         struct list_head list;
 
         free_recv_msg_list(&intf->waiting_msgs);
@@ -353,10 +352,10 @@ static void clean_up_interface_data(ipmi_smi_t intf)
 
         /* Wholesale remove all the entries from the list in the
          * interface and wait for RCU to know that none are in use. */
-        spin_lock_irqsave(&intf->cmd_rcvrs_lock, flags);
+        down(&intf->cmd_rcvrs_lock);
         list_add_rcu(&list, &intf->cmd_rcvrs);
         list_del_rcu(&intf->cmd_rcvrs);
-        spin_unlock_irqrestore(&intf->cmd_rcvrs_lock, flags);
+        up(&intf->cmd_rcvrs_lock);
         synchronize_rcu();
 
         list_for_each_entry_safe(rcvr, rcvr2, &list, link)
@@ -812,7 +811,7 @@ int ipmi_destroy_user(ipmi_user_t user)
          * since other things may be using it till we do
          * synchronize_rcu()) then free everything in that list.
          */
-        spin_lock_irqsave(&intf->cmd_rcvrs_lock, flags);
+        down(&intf->cmd_rcvrs_lock);
         list_for_each_safe_rcu(entry1, entry2, &intf->cmd_rcvrs) {
                 rcvr = list_entry(entry1, struct cmd_rcvr, link);
                 if (rcvr->user == user) {
@@ -821,7 +820,7 @@ int ipmi_destroy_user(ipmi_user_t user)
                         rcvrs = rcvr;
                 }
         }
-        spin_unlock_irqrestore(&intf->cmd_rcvrs_lock, flags);
+        up(&intf->cmd_rcvrs_lock);
         synchronize_rcu();
         while (rcvrs) {
                 rcvr = rcvrs;
@@ -950,7 +949,7 @@ int ipmi_register_for_cmd(ipmi_user_t   user,
         rcvr->netfn = netfn;
         rcvr->user = user;
 
-        spin_lock_irq(&intf->cmd_rcvrs_lock);
+        down(&intf->cmd_rcvrs_lock);
         /* Make sure the command/netfn is not already registered. */
         entry = find_cmd_rcvr(intf, netfn, cmd);
         if (entry) {
@@ -961,7 +960,7 @@ int ipmi_register_for_cmd(ipmi_user_t   user,
         list_add_rcu(&rcvr->link, &intf->cmd_rcvrs);
 
  out_unlock:
-        spin_unlock_irq(&intf->cmd_rcvrs_lock);
+        up(&intf->cmd_rcvrs_lock);
         if (rv)
                 kfree(rcvr);
 
@@ -975,17 +974,17 @@ int ipmi_unregister_for_cmd(ipmi_user_t   user,
         ipmi_smi_t      intf = user->intf;
         struct cmd_rcvr *rcvr;
 
-        spin_lock_irq(&intf->cmd_rcvrs_lock);
+        down(&intf->cmd_rcvrs_lock);
         /* Make sure the command/netfn is not already registered. */
         rcvr = find_cmd_rcvr(intf, netfn, cmd);
         if ((rcvr) && (rcvr->user == user)) {
                 list_del_rcu(&rcvr->link);
-                spin_unlock_irq(&intf->cmd_rcvrs_lock);
+                up(&intf->cmd_rcvrs_lock);
                 synchronize_rcu();
                 kfree(rcvr);
                 return 0;
         } else {
-                spin_unlock_irq(&intf->cmd_rcvrs_lock);
+                up(&intf->cmd_rcvrs_lock);
                 return -ENOENT;
         }
 }
@@ -1858,7 +1857,7 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
         spin_lock_init(&intf->events_lock);
         INIT_LIST_HEAD(&intf->waiting_events);
         intf->waiting_events_count = 0;
-        spin_lock_init(&intf->cmd_rcvrs_lock);
+        init_MUTEX(&intf->cmd_rcvrs_lock);
         INIT_LIST_HEAD(&intf->cmd_rcvrs);
         init_waitqueue_head(&intf->waitq);
 
@@ -2058,14 +2057,14 @@ static int handle_ipmb_get_msg_cmd(ipmi_smi_t          intf,
         netfn = msg->rsp[4] >> 2;
         cmd = msg->rsp[8];
 
-        spin_lock_irqsave(&intf->cmd_rcvrs_lock, flags);
+        rcu_read_lock();
         rcvr = find_cmd_rcvr(intf, netfn, cmd);
         if (rcvr) {
                 user = rcvr->user;
                 kref_get(&user->refcount);
         } else
                 user = NULL;
-        spin_unlock_irqrestore(&intf->cmd_rcvrs_lock, flags);
+        rcu_read_unlock();
 
         if (user == NULL) {
                 /* We didn't find a user, deliver an error response. */
@@ -2238,14 +2237,14 @@ static int handle_lan_get_msg_cmd(ipmi_smi_t          intf,
         netfn = msg->rsp[6] >> 2;
         cmd = msg->rsp[10];
 
-        spin_lock_irqsave(&intf->cmd_rcvrs_lock, flags);
+        rcu_read_lock();
         rcvr = find_cmd_rcvr(intf, netfn, cmd);
         if (rcvr) {
                 user = rcvr->user;
                 kref_get(&user->refcount);
         } else
                 user = NULL;
-        spin_unlock_irqrestore(&intf->cmd_rcvrs_lock, flags);
+        rcu_read_unlock();
 
         if (user == NULL) {
                 /* We didn't find a user, just give up. */