[PATCH] ipmi: use refcount in message handler

This patch is rather large, but it really can't be done in smaller chunks
easily and I believe it is an important change.  This has been out and tested
for a while in the latest IPMI driver release.  There are no functional
changes, just changes as necessary to convert the locking over (and a few
minor style updates).

The IPMI driver uses read/write locks to ensure that things exist while they
are in use.  This is bad from a number of points of view.  This patch removes
the rwlocks and uses refcounts and RCU lists to manage what the locks did.

Signed-off-by: Corey Minyard <minyard@acm.org>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 499 insertions, 459 deletions

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 32fa82c78c73..320d7f035bf9 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -38,13 +38,13 @@
 #include <linux/sched.h>
 #include <linux/poll.h>
 #include <linux/spinlock.h>
-#include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <linux/ipmi.h>
 #include <linux/ipmi_smi.h>
 #include <linux/notifier.h>
 #include <linux/init.h>
 #include <linux/proc_fs.h>
+#include <linux/rcupdate.h>
 
 #define PFX "IPMI message handler: "
 
@@ -65,10 +65,19 @@ struct proc_dir_entry *proc_ipmi_root = NULL;
    the max message timer.  This is in milliseconds. */
 #define MAX_MSG_TIMEOUT         60000
 
+
+/*
+ * The main "user" data structure.
+ */
 struct ipmi_user
 {
         struct list_head link;
 
+        /* Set to "0" when the user is destroyed. */
+        int valid;
+
+        struct kref refcount;
+
         /* The upper layer that handles receive messages. */
         struct ipmi_user_hndl *handler;
         void             *handler_data;
@@ -87,6 +96,15 @@ struct cmd_rcvr
         ipmi_user_t   user;
         unsigned char netfn;
         unsigned char cmd;
+
+        /*
+         * This is used to form a linked lised during mass deletion.
+         * Since this is in an RCU list, we cannot use the link above
+         * or change any data until the RCU period completes.  So we
+         * use this next variable during mass deletion so we can have
+         * a list and don't have to wait and restart the search on
+         * every individual deletion of a command. */
+        struct cmd_rcvr *next;
 };
 
 struct seq_table
@@ -150,13 +168,11 @@ struct ipmi_smi
         /* What interface number are we? */
         int intf_num;
 
-        /* The list of upper layers that are using me.  We read-lock
-           this when delivering messages to the upper layer to keep
-           the user from going away while we are processing the
-           message.  This means that you cannot add or delete a user
-           from the receive callback. */
-        rwlock_t                users_lock;
-        struct list_head        users;
+        struct kref refcount;
+
+        /* The list of upper layers that are using me.  seq_lock
+         * protects this. */
+        struct list_head users;
 
         /* Used for wake ups at startup. */
         wait_queue_head_t waitq;
@@ -193,7 +209,7 @@ struct ipmi_smi
 
         /* The list of command receivers that are registered for commands
            on this interface. */
-        rwlock_t         cmd_rcvr_lock;
+        spinlock_t       cmd_rcvrs_lock;
         struct list_head cmd_rcvrs;
 
         /* Events that were queues because no one was there to receive
@@ -296,16 +312,17 @@ struct ipmi_smi
         unsigned int events;
 };
 
+/* Used to mark an interface entry that cannot be used but is not a
+ * free entry, either, primarily used at creation and deletion time so
+ * a slot doesn't get reused too quickly. */
+#define IPMI_INVALID_INTERFACE_ENTRY ((ipmi_smi_t) ((long) 1))
+#define IPMI_INVALID_INTERFACE(i) (((i) == NULL) \
+                                   || (i == IPMI_INVALID_INTERFACE_ENTRY))
+
 #define MAX_IPMI_INTERFACES 4
 static ipmi_smi_t ipmi_interfaces[MAX_IPMI_INTERFACES];
 
-/* Used to keep interfaces from going away while operations are
-   operating on interfaces.  Grab read if you are not modifying the
-   interfaces, write if you are. */
-static DECLARE_RWSEM(interfaces_sem);
-
-/* Directly protects the ipmi_interfaces data structure.  This is
-   claimed in the timer interrupt. */
+/* Directly protects the ipmi_interfaces data structure. */
 static DEFINE_SPINLOCK(interfaces_lock);
 
 /* List of watchers that want to know when smi's are added and
@@ -313,20 +330,73 @@ static DEFINE_SPINLOCK(interfaces_lock);
 static struct list_head smi_watchers = LIST_HEAD_INIT(smi_watchers);
 static DECLARE_RWSEM(smi_watchers_sem);
 
+
+static void free_recv_msg_list(struct list_head *q)
+{
+        struct ipmi_recv_msg *msg, *msg2;
+
+        list_for_each_entry_safe(msg, msg2, q, link) {
+                list_del(&msg->link);
+                ipmi_free_recv_msg(msg);
+        }
+}
+
+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);
+        free_recv_msg_list(&intf->waiting_events);
+
+        /* 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);
+        list_add_rcu(&list, &intf->cmd_rcvrs);
+        list_del_rcu(&intf->cmd_rcvrs);
+        spin_unlock_irqrestore(&intf->cmd_rcvrs_lock, flags);
+        synchronize_rcu();
+
+        list_for_each_entry_safe(rcvr, rcvr2, &list, link)
+                kfree(rcvr);
+
+        for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
+                if ((intf->seq_table[i].inuse)
+                    && (intf->seq_table[i].recv_msg))
+                {
+                        ipmi_free_recv_msg(intf->seq_table[i].recv_msg);
+                }
+        }
+}
+
+static void intf_free(struct kref *ref)
+{
+        ipmi_smi_t intf = container_of(ref, struct ipmi_smi, refcount);
+
+        clean_up_interface_data(intf);
+        kfree(intf);
+}
+
 int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 {
-        int i;
+        int           i;
+        unsigned long flags;
 
-        down_read(&interfaces_sem);
         down_write(&smi_watchers_sem);
         list_add(&(watcher->link), &smi_watchers);
+        up_write(&smi_watchers_sem);
+        spin_lock_irqsave(&interfaces_lock, flags);
         for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                if (ipmi_interfaces[i] != NULL) {
-                        watcher->new_smi(i);
-                }
+                ipmi_smi_t intf = ipmi_interfaces[i];
+                if (IPMI_INVALID_INTERFACE(intf))
+                        continue;
+                spin_unlock_irqrestore(&interfaces_lock, flags);
+                watcher->new_smi(i);
+                spin_lock_irqsave(&interfaces_lock, flags);
         }
-        up_write(&smi_watchers_sem);
-        up_read(&interfaces_sem);
+        spin_unlock_irqrestore(&interfaces_lock, flags);
         return 0;
 }
 
@@ -471,8 +541,8 @@ static void deliver_response(struct ipmi_recv_msg *msg)
                 }
                 ipmi_free_recv_msg(msg);
         } else {
-                msg->user->handler->ipmi_recv_hndl(msg,
-                                                   msg->user->handler_data);
+                ipmi_user_t user = msg->user;
+                user->handler->ipmi_recv_hndl(msg, user->handler_data);
         }
 }
 
@@ -662,15 +732,18 @@ int ipmi_create_user(unsigned int          if_num,
         if (! new_user)
                 return -ENOMEM;
 
-        down_read(&interfaces_sem);
-        if ((if_num >= MAX_IPMI_INTERFACES) || ipmi_interfaces[if_num] == NULL)
-        {
-                rv = -EINVAL;
-                goto out_unlock;
+        spin_lock_irqsave(&interfaces_lock, flags);
+        intf = ipmi_interfaces[if_num];
+        if ((if_num >= MAX_IPMI_INTERFACES) || IPMI_INVALID_INTERFACE(intf)) {
+                spin_unlock_irqrestore(&interfaces_lock, flags);
+                return -EINVAL;
         }
 
-        intf = ipmi_interfaces[if_num];
+        /* Note that each existing user holds a refcount to the interface. */
+        kref_get(&intf->refcount);
+        spin_unlock_irqrestore(&interfaces_lock, flags);
 
+        kref_init(&new_user->refcount);
         new_user->handler = handler;
         new_user->handler_data = handler_data;
         new_user->intf = intf;
@@ -678,98 +751,92 @@ int ipmi_create_user(unsigned int          if_num,
 
         if (!try_module_get(intf->handlers->owner)) {
                 rv = -ENODEV;
-                goto out_unlock;
+                goto out_err;
         }
 
         if (intf->handlers->inc_usecount) {
                 rv = intf->handlers->inc_usecount(intf->send_info);
                 if (rv) {
                         module_put(intf->handlers->owner);
-                        goto out_unlock;
+                        goto out_err;
                 }
         }
 
-        write_lock_irqsave(&intf->users_lock, flags);
-        list_add_tail(&new_user->link, &intf->users);
-        write_unlock_irqrestore(&intf->users_lock, flags);
-
- out_unlock:    
-        if (rv) {
-                kfree(new_user);
-        } else {
-                *user = new_user;
-        }
+        new_user->valid = 1;
+        spin_lock_irqsave(&intf->seq_lock, flags);
+        list_add_rcu(&new_user->link, &intf->users);
+        spin_unlock_irqrestore(&intf->seq_lock, flags);
+        *user = new_user;
+        return 0;
 
-        up_read(&interfaces_sem);
+ out_err:
+        kfree(new_user);
+        kref_put(&intf->refcount, intf_free);
         return rv;
 }
 
-static int ipmi_destroy_user_nolock(ipmi_user_t user)
+static void free_user(struct kref *ref)
+{
+        ipmi_user_t user = container_of(ref, struct ipmi_user, refcount);
+        kfree(user);
+}
+
+int ipmi_destroy_user(ipmi_user_t user)
 {
         int              rv = -ENODEV;
-        ipmi_user_t      t_user;
-        struct cmd_rcvr  *rcvr, *rcvr2;
+        ipmi_smi_t       intf = user->intf;
         int              i;
         unsigned long    flags;
+        struct cmd_rcvr  *rcvr;
+        struct list_head *entry1, *entry2;
+        struct cmd_rcvr  *rcvrs = NULL;
 
-        /* Find the user and delete them from the list. */
-        list_for_each_entry(t_user, &(user->intf->users), link) {
-                if (t_user == user) {
-                        list_del(&t_user->link);
-                        rv = 0;
-                        break;
-                }
-        }
+        user->valid = 1;
 
-        if (rv) {
-                goto out_unlock;
-        }
+        /* Remove the user from the interface's sequence table. */
+        spin_lock_irqsave(&intf->seq_lock, flags);
+        list_del_rcu(&user->link);
 
-        /* Remove the user from the interfaces sequence table. */
-        spin_lock_irqsave(&(user->intf->seq_lock), flags);
         for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
-                if (user->intf->seq_table[i].inuse
-                    && (user->intf->seq_table[i].recv_msg->user == user))
+                if (intf->seq_table[i].inuse
+                    && (intf->seq_table[i].recv_msg->user == user))
                 {
-                        user->intf->seq_table[i].inuse = 0;
+                        intf->seq_table[i].inuse = 0;
                 }
         }
-        spin_unlock_irqrestore(&(user->intf->seq_lock), flags);
-
-        /* Remove the user from the command receiver's table. */
-        write_lock_irqsave(&(user->intf->cmd_rcvr_lock), flags);
-        list_for_each_entry_safe(rcvr, rcvr2, &(user->intf->cmd_rcvrs), link) {
+        spin_unlock_irqrestore(&intf->seq_lock, flags);
+
+        /*
+         * Remove the user from the command receiver's table.  First
+         * we build a list of everything (not using the standard link,
+         * 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);
+        list_for_each_safe_rcu(entry1, entry2, &intf->cmd_rcvrs) {
+                rcvr = list_entry(entry1, struct cmd_rcvr, link);
                 if (rcvr->user == user) {
-                        list_del(&rcvr->link);
-                        kfree(rcvr);
+                        list_del_rcu(&rcvr->link);
+                        rcvr->next = rcvrs;
+                        rcvrs = rcvr;
                 }
         }
-        write_unlock_irqrestore(&(user->intf->cmd_rcvr_lock), flags);
+        spin_unlock_irqrestore(&intf->cmd_rcvrs_lock, flags);
+        synchronize_rcu();
+        while (rcvrs) {
+                rcvr = rcvrs;
+                rcvrs = rcvr->next;
+                kfree(rcvr);
+        }
 
-        kfree(user);
+        module_put(intf->handlers->owner);
+        if (intf->handlers->dec_usecount)
+                intf->handlers->dec_usecount(intf->send_info);
 
- out_unlock:
+        kref_put(&intf->refcount, intf_free);
 
-        return rv;
-}
-
-int ipmi_destroy_user(ipmi_user_t user)
-{
-        int           rv;
-        ipmi_smi_t    intf = user->intf;
-        unsigned long flags;
+        kref_put(&user->refcount, free_user);
 
-        down_read(&interfaces_sem);
-        write_lock_irqsave(&intf->users_lock, flags);
-        rv = ipmi_destroy_user_nolock(user);
-        if (!rv) {
-                module_put(intf->handlers->owner);
-                if (intf->handlers->dec_usecount)
-                        intf->handlers->dec_usecount(intf->send_info);
-        }
-                
-        write_unlock_irqrestore(&intf->users_lock, flags);
-        up_read(&interfaces_sem);
         return rv;
 }
 
@@ -823,62 +890,78 @@ int ipmi_get_my_LUN(ipmi_user_t   user,
 
 int ipmi_set_gets_events(ipmi_user_t user, int val)
 {
-        unsigned long         flags;
-        struct ipmi_recv_msg  *msg, *msg2;
+        unsigned long        flags;
+        ipmi_smi_t           intf = user->intf;
+        struct ipmi_recv_msg *msg, *msg2;
+        struct list_head     msgs;
 
-        read_lock(&(user->intf->users_lock));
-        spin_lock_irqsave(&(user->intf->events_lock), flags);
+        INIT_LIST_HEAD(&msgs);
+
+        spin_lock_irqsave(&intf->events_lock, flags);
         user->gets_events = val;
 
         if (val) {
                 /* Deliver any queued events. */
-                list_for_each_entry_safe(msg, msg2, &(user->intf->waiting_events), link) {
+                list_for_each_entry_safe(msg, msg2, &intf->waiting_events, link) {
                         list_del(&msg->link);
-                        msg->user = user;
-                        deliver_response(msg);
+                        list_add_tail(&msg->link, &msgs);
                 }
         }
-        
-        spin_unlock_irqrestore(&(user->intf->events_lock), flags);
-        read_unlock(&(user->intf->users_lock));
+
+        /* Hold the events lock while doing this to preserve order. */
+        list_for_each_entry_safe(msg, msg2, &msgs, link) {
+                msg->user = user;
+                kref_get(&user->refcount);
+                deliver_response(msg);
+        }
+
+        spin_unlock_irqrestore(&intf->events_lock, flags);
 
         return 0;
 }
 
+static struct cmd_rcvr *find_cmd_rcvr(ipmi_smi_t    intf,
+                                      unsigned char netfn,
+                                      unsigned char cmd)
+{
+        struct cmd_rcvr *rcvr;
+
+        list_for_each_entry_rcu(rcvr, &intf->cmd_rcvrs, link) {
+                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd))
+                        return rcvr;
+        }
+        return NULL;
+}
+
 int ipmi_register_for_cmd(ipmi_user_t   user,
                           unsigned char netfn,
                           unsigned char cmd)
 {
-        struct cmd_rcvr  *cmp;
-        unsigned long    flags;
-        struct cmd_rcvr  *rcvr;
-        int              rv = 0;
+        ipmi_smi_t      intf = user->intf;
+        struct cmd_rcvr *rcvr;
+        struct cmd_rcvr *entry;
+        int             rv = 0;
 
 
         rcvr = kmalloc(sizeof(*rcvr), GFP_KERNEL);
         if (! rcvr)
                 return -ENOMEM;
+        rcvr->cmd = cmd;
+        rcvr->netfn = netfn;
+        rcvr->user = user;
 
-        read_lock(&(user->intf->users_lock));
-        write_lock_irqsave(&(user->intf->cmd_rcvr_lock), flags);
+        spin_lock_irq(&intf->cmd_rcvrs_lock);
         /* Make sure the command/netfn is not already registered. */
-        list_for_each_entry(cmp, &(user->intf->cmd_rcvrs), link) {
-                if ((cmp->netfn == netfn) && (cmp->cmd == cmd)) {
-                        rv = -EBUSY;
-                        break;
-                }
-        }
-
-        if (! rv) {
-                rcvr->cmd = cmd;
-                rcvr->netfn = netfn;
-                rcvr->user = user;
-                list_add_tail(&(rcvr->link), &(user->intf->cmd_rcvrs));
+        entry = find_cmd_rcvr(intf, netfn, cmd);
+        if (entry) {
+                rv = -EBUSY;
+                goto out_unlock;
         }
 
-        write_unlock_irqrestore(&(user->intf->cmd_rcvr_lock), flags);
-        read_unlock(&(user->intf->users_lock));
+        list_add_rcu(&rcvr->link, &intf->cmd_rcvrs);
 
+ out_unlock:
+        spin_unlock_irq(&intf->cmd_rcvrs_lock);
         if (rv)
                 kfree(rcvr);
 
@@ -889,31 +972,28 @@ int ipmi_unregister_for_cmd(ipmi_user_t   user,
                             unsigned char netfn,
                             unsigned char cmd)
 {
-        unsigned long    flags;
-        struct cmd_rcvr  *rcvr;
-        int              rv = -ENOENT;
+        ipmi_smi_t      intf = user->intf;
+        struct cmd_rcvr *rcvr;
 
-        read_lock(&(user->intf->users_lock));
-        write_lock_irqsave(&(user->intf->cmd_rcvr_lock), flags);
+        spin_lock_irq(&intf->cmd_rcvrs_lock);
         /* Make sure the command/netfn is not already registered. */
-        list_for_each_entry(rcvr, &(user->intf->cmd_rcvrs), link) {
-                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)) {
-                        rv = 0;
-                        list_del(&rcvr->link);
-                        kfree(rcvr);
-                        break;
-                }
+        rcvr = find_cmd_rcvr(intf, netfn, cmd);
+        if ((rcvr) && (rcvr->user == user)) {
+                list_del_rcu(&rcvr->link);
+                spin_unlock_irq(&intf->cmd_rcvrs_lock);
+                synchronize_rcu();
+                kfree(rcvr);
+                return 0;
+        } else {
+                spin_unlock_irq(&intf->cmd_rcvrs_lock);
+                return -ENOENT;
         }
-        write_unlock_irqrestore(&(user->intf->cmd_rcvr_lock), flags);
-        read_unlock(&(user->intf->users_lock));
-
-        return rv;
 }
 
 void ipmi_user_set_run_to_completion(ipmi_user_t user, int val)
 {
-        user->intf->handlers->set_run_to_completion(user->intf->send_info,
-                                                    val);
+        ipmi_smi_t intf = user->intf;
+        intf->handlers->set_run_to_completion(intf->send_info, val);
 }
 
 static unsigned char
@@ -1010,19 +1090,19 @@ static inline void format_lan_msg(struct ipmi_smi_msg   *smi_msg,
    supplied in certain circumstances (mainly at panic time).  If
    messages are supplied, they will be freed, even if an error
    occurs. */
-static inline int i_ipmi_request(ipmi_user_t          user,
-                                 ipmi_smi_t           intf,
-                                 struct ipmi_addr     *addr,
-                                 long                 msgid,
-                                 struct kernel_ipmi_msg *msg,
-                                 void                 *user_msg_data,
-                                 void                 *supplied_smi,
-                                 struct ipmi_recv_msg *supplied_recv,
-                                 int                  priority,
-                                 unsigned char        source_address,
-                                 unsigned char        source_lun,
-                                 int                  retries,
-                                 unsigned int         retry_time_ms)
+static int i_ipmi_request(ipmi_user_t          user,
+                          ipmi_smi_t           intf,
+                          struct ipmi_addr     *addr,
+                          long                 msgid,
+                          struct kernel_ipmi_msg *msg,
+                          void                 *user_msg_data,
+                          void                 *supplied_smi,
+                          struct ipmi_recv_msg *supplied_recv,
+                          int                  priority,
+                          unsigned char        source_address,
+                          unsigned char        source_lun,
+                          int                  retries,
+                          unsigned int         retry_time_ms)
 {
         int                  rv = 0;
         struct ipmi_smi_msg  *smi_msg;
@@ -1051,6 +1131,8 @@ static inline int i_ipmi_request(ipmi_user_t          user,
         }
 
         recv_msg->user = user;
+        if (user)
+                kref_get(&user->refcount);
         recv_msg->msgid = msgid;
         /* Store the message to send in the receive message so timeout
            responses can get the proper response data. */
@@ -1725,11 +1807,11 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
                       unsigned char            version_major,
                       unsigned char            version_minor,
                       unsigned char            slave_addr,
-                      ipmi_smi_t               *intf)
+                      ipmi_smi_t               *new_intf)
 {
         int              i, j;
         int              rv;
-        ipmi_smi_t       new_intf;
+        ipmi_smi_t       intf;
         unsigned long    flags;
 
 
@@ -1745,189 +1827,142 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
                         return -ENODEV;
         }
 
-        new_intf = kmalloc(sizeof(*new_intf), GFP_KERNEL);
-        if (!new_intf)
+        intf = kmalloc(sizeof(*intf), GFP_KERNEL);
+        if (!intf)
                 return -ENOMEM;
-        memset(new_intf, 0, sizeof(*new_intf));
-
-        new_intf->proc_dir = NULL;
+        memset(intf, 0, sizeof(*intf));
+        intf->intf_num = -1;
+        kref_init(&intf->refcount);
+        intf->version_major = version_major;
+        intf->version_minor = version_minor;
+        for (j = 0; j < IPMI_MAX_CHANNELS; j++) {
+                intf->channels[j].address = IPMI_BMC_SLAVE_ADDR;
+                intf->channels[j].lun = 2;
+        }
+        if (slave_addr != 0)
+                intf->channels[0].address = slave_addr;
+        INIT_LIST_HEAD(&intf->users);
+        intf->handlers = handlers;
+        intf->send_info = send_info;
+        spin_lock_init(&intf->seq_lock);
+        for (j = 0; j < IPMI_IPMB_NUM_SEQ; j++) {
+                intf->seq_table[j].inuse = 0;
+                intf->seq_table[j].seqid = 0;
+        }
+        intf->curr_seq = 0;
+#ifdef CONFIG_PROC_FS
+        spin_lock_init(&intf->proc_entry_lock);
+#endif
+        spin_lock_init(&intf->waiting_msgs_lock);
+        INIT_LIST_HEAD(&intf->waiting_msgs);
+        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_LIST_HEAD(&intf->cmd_rcvrs);
+        init_waitqueue_head(&intf->waitq);
+
+        spin_lock_init(&intf->counter_lock);
+        intf->proc_dir = NULL;
 
         rv = -ENOMEM;
-
-        down_write(&interfaces_sem);
+        spin_lock_irqsave(&interfaces_lock, flags);
         for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
                 if (ipmi_interfaces[i] == NULL) {
-                        new_intf->intf_num = i;
-                        new_intf->version_major = version_major;
-                        new_intf->version_minor = version_minor;
-                        for (j = 0; j < IPMI_MAX_CHANNELS; j++) {
-                                new_intf->channels[j].address
-                                        = IPMI_BMC_SLAVE_ADDR;
-                                new_intf->channels[j].lun = 2;
-                        }
-                        if (slave_addr != 0)
-                                new_intf->channels[0].address = slave_addr;
-                        rwlock_init(&(new_intf->users_lock));
-                        INIT_LIST_HEAD(&(new_intf->users));
-                        new_intf->handlers = handlers;
-                        new_intf->send_info = send_info;
-                        spin_lock_init(&(new_intf->seq_lock));
-                        for (j = 0; j < IPMI_IPMB_NUM_SEQ; j++) {
-                                new_intf->seq_table[j].inuse = 0;
-                                new_intf->seq_table[j].seqid = 0;
-                        }
-                        new_intf->curr_seq = 0;
-#ifdef CONFIG_PROC_FS
-                        spin_lock_init(&(new_intf->proc_entry_lock));
-#endif
-                        spin_lock_init(&(new_intf->waiting_msgs_lock));
-                        INIT_LIST_HEAD(&(new_intf->waiting_msgs));
-                        spin_lock_init(&(new_intf->events_lock));
-                        INIT_LIST_HEAD(&(new_intf->waiting_events));
-                        new_intf->waiting_events_count = 0;
-                        rwlock_init(&(new_intf->cmd_rcvr_lock));
-                        init_waitqueue_head(&new_intf->waitq);
-                        INIT_LIST_HEAD(&(new_intf->cmd_rcvrs));
-
-                        spin_lock_init(&(new_intf->counter_lock));
-
-                        spin_lock_irqsave(&interfaces_lock, flags);
-                        ipmi_interfaces[i] = new_intf;
-                        spin_unlock_irqrestore(&interfaces_lock, flags);
-
+                        intf->intf_num = i;
+                        /* Reserve the entry till we are done. */
+                        ipmi_interfaces[i] = IPMI_INVALID_INTERFACE_ENTRY;
                         rv = 0;
-                        *intf = new_intf;
                         break;
                 }
         }
+        spin_unlock_irqrestore(&interfaces_lock, flags);
+        if (rv)
+                goto out;
 
-        downgrade_write(&interfaces_sem);
-
-        if (rv == 0)
-                rv = add_proc_entries(*intf, i);
-
-        if (rv == 0) {
-                if ((version_major > 1)
-                    || ((version_major == 1) && (version_minor >= 5)))
-                {
-                        /* Start scanning the channels to see what is
-                           available. */
-                        (*intf)->null_user_handler = channel_handler;
-                        (*intf)->curr_channel = 0;
-                        rv = send_channel_info_cmd(*intf, 0);
-                        if (rv)
-                                goto out;
+        /* FIXME - this is an ugly kludge, this sets the intf for the
+           caller before sending any messages with it. */
+        *new_intf = intf;
 
-                        /* Wait for the channel info to be read. */
-                        up_read(&interfaces_sem);
-                        wait_event((*intf)->waitq,
-                                   ((*intf)->curr_channel>=IPMI_MAX_CHANNELS));
-                        down_read(&interfaces_sem);
+        if ((version_major > 1)
+            || ((version_major == 1) && (version_minor >= 5)))
+        {
+                /* Start scanning the channels to see what is
+                   available. */
+                intf->null_user_handler = channel_handler;
+                intf->curr_channel = 0;
+                rv = send_channel_info_cmd(intf, 0);
+                if (rv)
+                        goto out;
 
-                        if (ipmi_interfaces[i] != new_intf)
-                                /* Well, it went away.  Just return. */
-                                goto out;
-                } else {
-                        /* Assume a single IPMB channel at zero. */
-                        (*intf)->channels[0].medium = IPMI_CHANNEL_MEDIUM_IPMB;
-                        (*intf)->channels[0].protocol
-                                = IPMI_CHANNEL_PROTOCOL_IPMB;
-                }
-
-                /* Call all the watcher interfaces to tell
-                   them that a new interface is available. */
-                call_smi_watchers(i);
+                /* Wait for the channel info to be read. */
+                wait_event(intf->waitq,
+                           intf->curr_channel >= IPMI_MAX_CHANNELS);
+        } else {
+                /* Assume a single IPMB channel at zero. */
+                intf->channels[0].medium = IPMI_CHANNEL_MEDIUM_IPMB;
+                intf->channels[0].protocol = IPMI_CHANNEL_PROTOCOL_IPMB;
         }
 
- out:
-        up_read(&interfaces_sem);
+        if (rv == 0)
+                rv = add_proc_entries(intf, i);
 
+ out:
         if (rv) {
-                if (new_intf->proc_dir)
-                        remove_proc_entries(new_intf);
-                kfree(new_intf);
+                if (intf->proc_dir)
+                        remove_proc_entries(intf);
+                kref_put(&intf->refcount, intf_free);
+                if (i < MAX_IPMI_INTERFACES) {
+                        spin_lock_irqsave(&interfaces_lock, flags);
+                        ipmi_interfaces[i] = NULL;
+                        spin_unlock_irqrestore(&interfaces_lock, flags);
+                }
+        } else {
+                spin_lock_irqsave(&interfaces_lock, flags);
+                ipmi_interfaces[i] = intf;
+                spin_unlock_irqrestore(&interfaces_lock, flags);
+                call_smi_watchers(i);
         }
 
         return rv;
 }
 
-static void free_recv_msg_list(struct list_head *q)
-{
-        struct ipmi_recv_msg *msg, *msg2;
-
-        list_for_each_entry_safe(msg, msg2, q, link) {
-                list_del(&msg->link);
-                ipmi_free_recv_msg(msg);
-        }
-}
-
-static void free_cmd_rcvr_list(struct list_head *q)
-{
-        struct cmd_rcvr  *rcvr, *rcvr2;
-
-        list_for_each_entry_safe(rcvr, rcvr2, q, link) {
-                list_del(&rcvr->link);
-                kfree(rcvr);
-        }
-}
-
-static void clean_up_interface_data(ipmi_smi_t intf)
-{
-        int i;
-
-        free_recv_msg_list(&(intf->waiting_msgs));
-        free_recv_msg_list(&(intf->waiting_events));
-        free_cmd_rcvr_list(&(intf->cmd_rcvrs));
-
-        for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++) {
-                if ((intf->seq_table[i].inuse)
-                    && (intf->seq_table[i].recv_msg))
-                {
-                        ipmi_free_recv_msg(intf->seq_table[i].recv_msg);
-                }       
-        }
-}
-
 int ipmi_unregister_smi(ipmi_smi_t intf)
 {
-        int                     rv = -ENODEV;
         int                     i;
         struct ipmi_smi_watcher *w;
         unsigned long           flags;
 
-        down_write(&interfaces_sem);
-        if (list_empty(&(intf->users)))
-        {
-                for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                        if (ipmi_interfaces[i] == intf) {
-                                remove_proc_entries(intf);
-                                spin_lock_irqsave(&interfaces_lock, flags);
-                                ipmi_interfaces[i] = NULL;
-                                clean_up_interface_data(intf);
-                                spin_unlock_irqrestore(&interfaces_lock,flags);
-                                kfree(intf);
-                                rv = 0;
-                                goto out_call_watcher;
-                        }
+        spin_lock_irqsave(&interfaces_lock, flags);
+        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
+                if (ipmi_interfaces[i] == intf) {
+                        /* Set the interface number reserved until we
+                         * are done. */
+                        ipmi_interfaces[i] = IPMI_INVALID_INTERFACE_ENTRY;
+                        intf->intf_num = -1;
+                        break;
                 }
-        } else {
-                rv = -EBUSY;
         }
-        up_write(&interfaces_sem);
+        spin_unlock_irqrestore(&interfaces_lock,flags);
 
-        return rv;
+        if (i == MAX_IPMI_INTERFACES)
+                return -ENODEV;
 
- out_call_watcher:
-        downgrade_write(&interfaces_sem);
+        remove_proc_entries(intf);
 
         /* Call all the watcher interfaces to tell them that
            an interface is gone. */
         down_read(&smi_watchers_sem);
-        list_for_each_entry(w, &smi_watchers, link) {
+        list_for_each_entry(w, &smi_watchers, link)
                 w->smi_gone(i);
-        }
         up_read(&smi_watchers_sem);
-        up_read(&interfaces_sem);
+
+        /* Allow the entry to be reused now. */
+        spin_lock_irqsave(&interfaces_lock, flags);
+        ipmi_interfaces[i] = NULL;
+        spin_unlock_irqrestore(&interfaces_lock,flags);
+
+        kref_put(&intf->refcount, intf_free);
         return 0;
 }
 
@@ -1998,14 +2033,14 @@ static int handle_ipmb_get_msg_rsp(ipmi_smi_t          intf,
 static int handle_ipmb_get_msg_cmd(ipmi_smi_t          intf,
                                    struct ipmi_smi_msg *msg)
 {
-        struct cmd_rcvr       *rcvr;
-        int                   rv = 0;
-        unsigned char         netfn;
-        unsigned char         cmd;
-        ipmi_user_t           user = NULL;
-        struct ipmi_ipmb_addr *ipmb_addr;
-        struct ipmi_recv_msg  *recv_msg;
-        unsigned long         flags;
+        struct cmd_rcvr          *rcvr;
+        int                      rv = 0;
+        unsigned char            netfn;
+        unsigned char            cmd;
+        ipmi_user_t              user = NULL;
+        struct ipmi_ipmb_addr    *ipmb_addr;
+        struct ipmi_recv_msg     *recv_msg;
+        unsigned long            flags;
 
         if (msg->rsp_size < 10) {
                 /* Message not big enough, just ignore it. */
@@ -2023,16 +2058,14 @@ static int handle_ipmb_get_msg_cmd(ipmi_smi_t          intf,
         netfn = msg->rsp[4] >> 2;
         cmd = msg->rsp[8];
 
-        read_lock(&(intf->cmd_rcvr_lock));
-        
-        /* Find the command/netfn. */
-        list_for_each_entry(rcvr, &(intf->cmd_rcvrs), link) {
-                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)) {
-                        user = rcvr->user;
-                        break;
-                }
-        }
-        read_unlock(&(intf->cmd_rcvr_lock));
+        spin_lock_irqsave(&intf->cmd_rcvrs_lock, flags);
+        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);
 
         if (user == NULL) {
                 /* We didn't find a user, deliver an error response. */
@@ -2079,6 +2112,7 @@ static int handle_ipmb_get_msg_cmd(ipmi_smi_t          intf,
                            message, so requeue it for handling
                            later. */
                         rv = 1;
+                        kref_put(&user->refcount, free_user);
                 } else {
                         /* Extract the source address from the data. */
                         ipmb_addr = (struct ipmi_ipmb_addr *) &recv_msg->addr;
@@ -2179,14 +2213,14 @@ static int handle_lan_get_msg_rsp(ipmi_smi_t          intf,
 static int handle_lan_get_msg_cmd(ipmi_smi_t          intf,
                                   struct ipmi_smi_msg *msg)
 {
-        struct cmd_rcvr       *rcvr;
-        int                   rv = 0;
-        unsigned char         netfn;
-        unsigned char         cmd;
-        ipmi_user_t           user = NULL;
-        struct ipmi_lan_addr  *lan_addr;
-        struct ipmi_recv_msg  *recv_msg;
-        unsigned long         flags;
+        struct cmd_rcvr          *rcvr;
+        int                      rv = 0;
+        unsigned char            netfn;
+        unsigned char            cmd;
+        ipmi_user_t              user = NULL;
+        struct ipmi_lan_addr     *lan_addr;
+        struct ipmi_recv_msg     *recv_msg;
+        unsigned long            flags;
 
         if (msg->rsp_size < 12) {
                 /* Message not big enough, just ignore it. */
@@ -2204,19 +2238,17 @@ static int handle_lan_get_msg_cmd(ipmi_smi_t          intf,
         netfn = msg->rsp[6] >> 2;
         cmd = msg->rsp[10];
 
-        read_lock(&(intf->cmd_rcvr_lock));
-
-        /* Find the command/netfn. */
-        list_for_each_entry(rcvr, &(intf->cmd_rcvrs), link) {
-                if ((rcvr->netfn == netfn) && (rcvr->cmd == cmd)) {
-                        user = rcvr->user;
-                        break;
-                }
-        }
-        read_unlock(&(intf->cmd_rcvr_lock));
+        spin_lock_irqsave(&intf->cmd_rcvrs_lock, flags);
+        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);
 
         if (user == NULL) {
-                /* We didn't find a user, deliver an error response. */
+                /* We didn't find a user, just give up. */
                 spin_lock_irqsave(&intf->counter_lock, flags);
                 intf->unhandled_commands++;
                 spin_unlock_irqrestore(&intf->counter_lock, flags);
@@ -2235,6 +2267,7 @@ static int handle_lan_get_msg_cmd(ipmi_smi_t          intf,
                            message, so requeue it for handling
                            later. */
                         rv = 1;
+                        kref_put(&user->refcount, free_user);
                 } else {
                         /* Extract the source address from the data. */
                         lan_addr = (struct ipmi_lan_addr *) &recv_msg->addr;
@@ -2286,8 +2319,6 @@ static void copy_event_into_recv_msg(struct ipmi_recv_msg *recv_msg,
         recv_msg->msg.data_len = msg->rsp_size - 3;
 }
 
-/* This will be called with the intf->users_lock read-locked, so no need
-   to do that here. */
 static int handle_read_event_rsp(ipmi_smi_t          intf,
                                  struct ipmi_smi_msg *msg)
 {
@@ -2313,7 +2344,7 @@ static int handle_read_event_rsp(ipmi_smi_t          intf,
 
         INIT_LIST_HEAD(&msgs);
 
-        spin_lock_irqsave(&(intf->events_lock), flags);
+        spin_lock_irqsave(&intf->events_lock, flags);
 
         spin_lock(&intf->counter_lock);
         intf->events++;
@@ -2321,12 +2352,14 @@ static int handle_read_event_rsp(ipmi_smi_t          intf,
 
         /* Allocate and fill in one message for every user that is getting
            events. */
-        list_for_each_entry(user, &(intf->users), link) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(user, &intf->users, link) {
                 if (! user->gets_events)
                         continue;
 
                 recv_msg = ipmi_alloc_recv_msg();
                 if (! recv_msg) {
+                        rcu_read_unlock();
                         list_for_each_entry_safe(recv_msg, recv_msg2, &msgs, link) {
                                 list_del(&recv_msg->link);
                                 ipmi_free_recv_msg(recv_msg);
@@ -2342,8 +2375,10 @@ static int handle_read_event_rsp(ipmi_smi_t          intf,
 
                 copy_event_into_recv_msg(recv_msg, msg);
                 recv_msg->user = user;
+                kref_get(&user->refcount);
                 list_add_tail(&(recv_msg->link), &msgs);
         }
+        rcu_read_unlock();
 
         if (deliver_count) {
                 /* Now deliver all the messages. */
@@ -2382,9 +2417,8 @@ static int handle_bmc_rsp(ipmi_smi_t          intf,
                           struct ipmi_smi_msg *msg)
 {
         struct ipmi_recv_msg *recv_msg;
-        int                  found = 0;
-        struct ipmi_user     *user;
         unsigned long        flags;
+        struct ipmi_user     *user;
 
         recv_msg = (struct ipmi_recv_msg *) msg->user_data;
         if (recv_msg == NULL)
@@ -2396,16 +2430,9 @@ static int handle_bmc_rsp(ipmi_smi_t          intf,
                 return 0;
         }
 
+        user = recv_msg->user;
         /* Make sure the user still exists. */
-        list_for_each_entry(user, &(intf->users), link) {
-                if (user == recv_msg->user) {
-                        /* Found it, so we can deliver it */
-                        found = 1;
-                        break;
-                }
-        }
-
-        if ((! found) && recv_msg->user) {
+        if (user && !user->valid) {
                 /* The user for the message went away, so give up. */
                 spin_lock_irqsave(&intf->counter_lock, flags);
                 intf->unhandled_local_responses++;
@@ -2486,7 +2513,7 @@ static int handle_new_recv_msg(ipmi_smi_t          intf,
         {
                 /* It's a response to a response we sent.  For this we
                    deliver a send message response to the user. */
-                struct ipmi_recv_msg *recv_msg = msg->user_data;
+                struct ipmi_recv_msg     *recv_msg = msg->user_data;
 
                 requeue = 0;
                 if (msg->rsp_size < 2)
@@ -2498,13 +2525,18 @@ static int handle_new_recv_msg(ipmi_smi_t          intf,
                         /* Invalid channel number */
                         goto out;
 
-                if (recv_msg) {
-                        recv_msg->recv_type = IPMI_RESPONSE_RESPONSE_TYPE;
-                        recv_msg->msg.data = recv_msg->msg_data;
-                        recv_msg->msg.data_len = 1;
-                        recv_msg->msg_data[0] = msg->rsp[2];
-                        deliver_response(recv_msg);
-                }
+                if (!recv_msg)
+                        goto out;
+
+                /* Make sure the user still exists. */
+                if (!recv_msg->user || !recv_msg->user->valid)
+                        goto out;
+
+                recv_msg->recv_type = IPMI_RESPONSE_RESPONSE_TYPE;
+                recv_msg->msg.data = recv_msg->msg_data;
+                recv_msg->msg.data_len = 1;
+                recv_msg->msg_data[0] = msg->rsp[2];
+                deliver_response(recv_msg);
         } else if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
                    && (msg->rsp[1] == IPMI_GET_MSG_CMD))
         {
@@ -2570,14 +2602,11 @@ void ipmi_smi_msg_received(ipmi_smi_t          intf,
         int           rv;
 
 
-        /* Lock the user lock so the user can't go away while we are
-           working on it. */
-        read_lock(&(intf->users_lock));
-
         if ((msg->data_size >= 2)
             && (msg->data[0] == (IPMI_NETFN_APP_REQUEST << 2))
             && (msg->data[1] == IPMI_SEND_MSG_CMD)
-            && (msg->user_data == NULL)) {
+            && (msg->user_data == NULL))
+        {
                 /* This is the local response to a command send, start
                    the timer for these.  The user_data will not be
                    NULL if this is a response send, and we will let
@@ -2612,46 +2641,46 @@ void ipmi_smi_msg_received(ipmi_smi_t          intf,
                 }
 
                 ipmi_free_smi_msg(msg);
-                goto out_unlock;
+                goto out;
         }
 
         /* To preserve message order, if the list is not empty, we
            tack this message onto the end of the list. */
-        spin_lock_irqsave(&(intf->waiting_msgs_lock), flags);
-        if (!list_empty(&(intf->waiting_msgs))) {
-                list_add_tail(&(msg->link), &(intf->waiting_msgs));
-                spin_unlock_irqrestore(&(intf->waiting_msgs_lock), flags);
-                goto out_unlock;
+        spin_lock_irqsave(&intf->waiting_msgs_lock, flags);
+        if (!list_empty(&intf->waiting_msgs)) {
+                list_add_tail(&msg->link, &intf->waiting_msgs);
+                spin_unlock(&intf->waiting_msgs_lock);
+                goto out;
         }
-        spin_unlock_irqrestore(&(intf->waiting_msgs_lock), flags);
+        spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
                 
         rv = handle_new_recv_msg(intf, msg);
         if (rv > 0) {
                 /* Could not handle the message now, just add it to a
                    list to handle later. */
-                spin_lock_irqsave(&(intf->waiting_msgs_lock), flags);
-                list_add_tail(&(msg->link), &(intf->waiting_msgs));
-                spin_unlock_irqrestore(&(intf->waiting_msgs_lock), flags);
+                spin_lock(&intf->waiting_msgs_lock);
+                list_add_tail(&msg->link, &intf->waiting_msgs);
+                spin_unlock(&intf->waiting_msgs_lock);
         } else if (rv == 0) {
                 ipmi_free_smi_msg(msg);
         }
 
- out_unlock:
-        read_unlock(&(intf->users_lock));
+ out:
+        return;
 }
 
 void ipmi_smi_watchdog_pretimeout(ipmi_smi_t intf)
 {
         ipmi_user_t user;
 
-        read_lock(&(intf->users_lock));
-        list_for_each_entry(user, &(intf->users), link) {
+        rcu_read_lock();
+        list_for_each_entry_rcu(user, &intf->users, link) {
                 if (! user->handler->ipmi_watchdog_pretimeout)
                         continue;
 
                 user->handler->ipmi_watchdog_pretimeout(user->handler_data);
         }
-        read_unlock(&(intf->users_lock));
+        rcu_read_unlock();
 }
 
 static void
@@ -2691,8 +2720,65 @@ smi_from_recv_msg(ipmi_smi_t intf, struct ipmi_recv_msg *recv_msg,
         return smi_msg;
 }
 
-static void
-ipmi_timeout_handler(long timeout_period)
+static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
+                              struct list_head *timeouts, long timeout_period,
+                              int slot, unsigned long *flags)
+{
+        struct ipmi_recv_msg *msg;
+
+        if (!ent->inuse)
+                return;
+
+        ent->timeout -= timeout_period;
+        if (ent->timeout > 0)
+                return;
+
+        if (ent->retries_left == 0) {
+                /* The message has used all its retries. */
+                ent->inuse = 0;
+                msg = ent->recv_msg;
+                list_add_tail(&msg->link, timeouts);
+                spin_lock(&intf->counter_lock);
+                if (ent->broadcast)
+                        intf->timed_out_ipmb_broadcasts++;
+                else if (ent->recv_msg->addr.addr_type == IPMI_LAN_ADDR_TYPE)
+                        intf->timed_out_lan_commands++;
+                else
+                        intf->timed_out_ipmb_commands++;
+                spin_unlock(&intf->counter_lock);
+        } else {
+                struct ipmi_smi_msg *smi_msg;
+                /* More retries, send again. */
+
+                /* Start with the max timer, set to normal
+                   timer after the message is sent. */
+                ent->timeout = MAX_MSG_TIMEOUT;
+                ent->retries_left--;
+                spin_lock(&intf->counter_lock);
+                if (ent->recv_msg->addr.addr_type == IPMI_LAN_ADDR_TYPE)
+                        intf->retransmitted_lan_commands++;
+                else
+                        intf->retransmitted_ipmb_commands++;
+                spin_unlock(&intf->counter_lock);
+
+                smi_msg = smi_from_recv_msg(intf, ent->recv_msg, slot,
+                                            ent->seqid);
+                if (! smi_msg)
+                        return;
+
+                spin_unlock_irqrestore(&intf->seq_lock, *flags);
+                /* Send the new message.  We send with a zero
+                 * priority.  It timed out, I doubt time is
+                 * that critical now, and high priority
+                 * messages are really only for messages to the
+                 * local MC, which don't get resent. */
+                intf->handlers->sender(intf->send_info,
+                                       smi_msg, 0);
+                spin_lock_irqsave(&intf->seq_lock, *flags);
+        }
+}
+
+static void ipmi_timeout_handler(long timeout_period)
 {
         ipmi_smi_t           intf;
         struct list_head     timeouts;
@@ -2706,14 +2792,14 @@ ipmi_timeout_handler(long timeout_period)
         spin_lock(&interfaces_lock);
         for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
                 intf = ipmi_interfaces[i];
-                if (intf == NULL)
+                if (IPMI_INVALID_INTERFACE(intf))
                         continue;
-
-                read_lock(&(intf->users_lock));
+                kref_get(&intf->refcount);
+                spin_unlock(&interfaces_lock);
 
                 /* See if any waiting messages need to be processed. */
-                spin_lock_irqsave(&(intf->waiting_msgs_lock), flags);
-                list_for_each_entry_safe(smi_msg, smi_msg2, &(intf->waiting_msgs), link) {
+                spin_lock_irqsave(&intf->waiting_msgs_lock, flags);
+                list_for_each_entry_safe(smi_msg, smi_msg2, &intf->waiting_msgs, link) {
                         if (! handle_new_recv_msg(intf, smi_msg)) {
                                 list_del(&smi_msg->link);
                                 ipmi_free_smi_msg(smi_msg);
@@ -2723,73 +2809,23 @@ ipmi_timeout_handler(long timeout_period)
                                 break;
                         }
                 }
-                spin_unlock_irqrestore(&(intf->waiting_msgs_lock), flags);
+                spin_unlock_irqrestore(&intf->waiting_msgs_lock, flags);
 
                 /* Go through the seq table and find any messages that
                    have timed out, putting them in the timeouts
                    list. */
-                spin_lock_irqsave(&(intf->seq_lock), flags);
-                for (j = 0; j < IPMI_IPMB_NUM_SEQ; j++) {
-                        struct seq_table *ent = &(intf->seq_table[j]);
-                        if (!ent->inuse)
-                                continue;
-
-                        ent->timeout -= timeout_period;
-                        if (ent->timeout > 0)
-                                continue;
-
-                        if (ent->retries_left == 0) {
-                                /* The message has used all its retries. */
-                                ent->inuse = 0;
-                                msg = ent->recv_msg;
-                                list_add_tail(&(msg->link), &timeouts);
-                                spin_lock(&intf->counter_lock);
-                                if (ent->broadcast)
-                                        intf->timed_out_ipmb_broadcasts++;
-                                else if (ent->recv_msg->addr.addr_type
-                                         == IPMI_LAN_ADDR_TYPE)
-                                        intf->timed_out_lan_commands++;
-                                else
-                                        intf->timed_out_ipmb_commands++;
-                                spin_unlock(&intf->counter_lock);
-                        } else {
-                                struct ipmi_smi_msg *smi_msg;
-                                /* More retries, send again. */
-
-                                /* Start with the max timer, set to normal
-                                   timer after the message is sent. */
-                                ent->timeout = MAX_MSG_TIMEOUT;
-                                ent->retries_left--;
-                                spin_lock(&intf->counter_lock);
-                                if (ent->recv_msg->addr.addr_type
-                                    == IPMI_LAN_ADDR_TYPE)
-                                        intf->retransmitted_lan_commands++;
-                                else
-                                        intf->retransmitted_ipmb_commands++;
-                                spin_unlock(&intf->counter_lock);
-                                smi_msg = smi_from_recv_msg(intf,
-                                                ent->recv_msg, j, ent->seqid);
-                                if (! smi_msg)
-                                        continue;
-
-                                spin_unlock_irqrestore(&(intf->seq_lock),flags);
-                                /* Send the new message.  We send with a zero
-                                 * priority.  It timed out, I doubt time is
-                                 * that critical now, and high priority
-                                 * messages are really only for messages to the
-                                 * local MC, which don't get resent. */
-                                intf->handlers->sender(intf->send_info,
-                                                        smi_msg, 0);
-                                spin_lock_irqsave(&(intf->seq_lock), flags);
-                        }
-                }
-                spin_unlock_irqrestore(&(intf->seq_lock), flags);
-
-                list_for_each_entry_safe(msg, msg2, &timeouts, link) {
+                spin_lock_irqsave(&intf->seq_lock, flags);
+                for (j = 0; j < IPMI_IPMB_NUM_SEQ; j++)
+                        check_msg_timeout(intf, &(intf->seq_table[j]),
+                                          &timeouts, timeout_period, j,
+                                          &flags);
+                spin_unlock_irqrestore(&intf->seq_lock, flags);
+
+                list_for_each_entry_safe(msg, msg2, &timeouts, link)
                         handle_msg_timeout(msg);
-                }
 
-                read_unlock(&(intf->users_lock));
+                kref_put(&intf->refcount, intf_free);
+                spin_lock(&interfaces_lock);
         }
         spin_unlock(&interfaces_lock);
 }
@@ -2802,7 +2838,7 @@ static void ipmi_request_event(void)
         spin_lock(&interfaces_lock);
         for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
                 intf = ipmi_interfaces[i];
-                if (intf == NULL)
+                if (IPMI_INVALID_INTERFACE(intf))
                         continue;
 
                 intf->handlers->request_events(intf->send_info);
@@ -2884,6 +2920,13 @@ struct ipmi_recv_msg *ipmi_alloc_recv_msg(void)
         return rv;
 }
 
+void ipmi_free_recv_msg(struct ipmi_recv_msg *msg)
+{
+        if (msg->user)
+                kref_put(&msg->user->refcount, free_user);
+        msg->done(msg);
+}
+
 #ifdef CONFIG_IPMI_PANIC_EVENT
 
 static void dummy_smi_done_handler(struct ipmi_smi_msg *msg)
@@ -2964,7 +3007,7 @@ static void send_panic_events(char *str)
         /* For every registered interface, send the event. */
         for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
                 intf = ipmi_interfaces[i];
-                if (intf == NULL)
+                if (IPMI_INVALID_INTERFACE(intf))
                         continue;
 
                 /* Send the event announcing the panic. */
@@ -2995,7 +3038,7 @@ static void send_panic_events(char *str)
                 int                   j;
 
                 intf = ipmi_interfaces[i];
-                if (intf == NULL)
+                if (IPMI_INVALID_INTERFACE(intf))
                         continue;
 
                 /* First job here is to figure out where to send the
@@ -3131,7 +3174,7 @@ static int panic_event(struct notifier_block *this,
         /* For every registered interface, set it to run to completion. */
         for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
                 intf = ipmi_interfaces[i];
-                if (intf == NULL)
+                if (IPMI_INVALID_INTERFACE(intf))
                         continue;
 
                 intf->handlers->set_run_to_completion(intf->send_info, 1);
@@ -3160,9 +3203,8 @@ static int ipmi_init_msghandler(void)
         printk(KERN_INFO "ipmi message handler version "
                IPMI_DRIVER_VERSION "\n");
 
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
+        for (i = 0; i < MAX_IPMI_INTERFACES; i++)
                 ipmi_interfaces[i] = NULL;
-        }
 
 #ifdef CONFIG_PROC_FS
         proc_ipmi_root = proc_mkdir("ipmi", NULL);
@@ -3258,3 +3300,4 @@ EXPORT_SYMBOL(ipmi_get_my_LUN);
 EXPORT_SYMBOL(ipmi_smi_add_proc_entry);
 EXPORT_SYMBOL(proc_ipmi_root);
 EXPORT_SYMBOL(ipmi_user_set_run_to_completion);
+EXPORT_SYMBOL(ipmi_free_recv_msg);
diff --git a/include/linux/ipmi.h b/include/linux/ipmi.h
index 938d55b813a5..d6276e60b3bf 100644
--- a/include/linux/ipmi.h
+++ b/include/linux/ipmi.h
@@ -256,10 +256,7 @@ struct ipmi_recv_msg
 };
 
 /* Allocate and free the receive message. */
-static inline void ipmi_free_recv_msg(struct ipmi_recv_msg *msg)
-{
-        msg->done(msg);
-}
+void ipmi_free_recv_msg(struct ipmi_recv_msg *msg);
 
 struct ipmi_user_hndl
 {