[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>

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 320d7f0..c1d06ba 100644 (file)
--- 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. */