[PATCH] IPMI: remove interface number limits

Remove the arbitrary limit of number of IPMI interfaces.  This has been tested
with 8 interfaces.

Signed-off-by: Corey Minyard <minyard@acm.org>
Cc: Carol Hebert <cah@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 97 insertions, 113 deletions

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index da13df46e984..761ed2699204 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -193,6 +193,9 @@ struct ipmi_smi
 
         struct kref refcount;
 
+        /* Used for a list of interfaces. */
+        struct list_head link;
+
         /* The list of upper layers that are using me.  seq_lock
          * protects this. */
         struct list_head users;
@@ -338,13 +341,6 @@ struct ipmi_smi
 };
 #define to_si_intf_from_dev(device) container_of(device, struct ipmi_smi, dev)
 
-/* 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))
-
 /**
  * The driver model view of the IPMI messaging driver.
  */
@@ -354,11 +350,8 @@ static struct device_driver ipmidriver = {
 };
 static DEFINE_MUTEX(ipmidriver_mutex);
 
-#define MAX_IPMI_INTERFACES 4
-static ipmi_smi_t ipmi_interfaces[MAX_IPMI_INTERFACES];
-
-/* Directly protects the ipmi_interfaces data structure. */
-static DEFINE_SPINLOCK(interfaces_lock);
+static struct list_head ipmi_interfaces = LIST_HEAD_INIT(ipmi_interfaces);
+static DEFINE_MUTEX(ipmi_interfaces_mutex);
 
 /* List of watchers that want to know when smi's are added and
    deleted. */
@@ -423,25 +416,50 @@ static void intf_free(struct kref *ref)
         kfree(intf);
 }
 
+struct watcher_entry {
+        struct list_head link;
+        int intf_num;
+};
+
 int ipmi_smi_watcher_register(struct ipmi_smi_watcher *watcher)
 {
-        int           i;
-        unsigned long flags;
+        ipmi_smi_t intf;
+        struct list_head to_deliver = LIST_HEAD_INIT(to_deliver);
+        struct watcher_entry *e, *e2;
+
+        mutex_lock(&ipmi_interfaces_mutex);
+
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+                if (intf->intf_num == -1)
+                        continue;
+                e = kmalloc(sizeof(*e), GFP_KERNEL);
+                if (!e)
+                        goto out_err;
+                e->intf_num = intf->intf_num;
+                list_add_tail(&e->link, &to_deliver);
+        }
 
         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++) {
-                ipmi_smi_t intf = ipmi_interfaces[i];
-                if (IPMI_INVALID_INTERFACE(intf))
-                        continue;
-                spin_unlock_irqrestore(&interfaces_lock, flags);
-                watcher->new_smi(i, intf->si_dev);
-                spin_lock_irqsave(&interfaces_lock, flags);
+
+        mutex_unlock(&ipmi_interfaces_mutex);
+
+        list_for_each_entry_safe(e, e2, &to_deliver, link) {
+                list_del(&e->link);
+                watcher->new_smi(e->intf_num, intf->si_dev);
+                kfree(e);
         }
-        spin_unlock_irqrestore(&interfaces_lock, flags);
+
+
         return 0;
+
+ out_err:
+        list_for_each_entry_safe(e, e2, &to_deliver, link) {
+                list_del(&e->link);
+                kfree(e);
+        }
+        return -ENOMEM;
 }
 
 int ipmi_smi_watcher_unregister(struct ipmi_smi_watcher *watcher)
@@ -776,17 +794,19 @@ int ipmi_create_user(unsigned int          if_num,
         if (!new_user)
                 return -ENOMEM;
 
-        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);
-                rv = -EINVAL;
-                goto out_kfree;
+        rcu_read_lock();
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+                if (intf->intf_num == if_num)
+                        goto found;
         }
+        rcu_read_unlock();
+        rv = -EINVAL;
+        goto out_kfree;
 
+ found:
         /* Note that each existing user holds a refcount to the interface. */
         kref_get(&intf->refcount);
-        spin_unlock_irqrestore(&interfaces_lock, flags);
+        rcu_read_unlock();
 
         kref_init(&new_user->refcount);
         new_user->handler = handler;
@@ -2449,9 +2469,10 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
         int              i, j;
         int              rv;
         ipmi_smi_t       intf;
-        unsigned long    flags;
+        ipmi_smi_t       tintf;
         int              version_major;
         int              version_minor;
+        struct list_head *link;
 
         version_major = ipmi_version_major(device_id);
         version_minor = ipmi_version_minor(device_id);
@@ -2477,7 +2498,7 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
                 kfree(intf);
                 return -ENOMEM;
         }
-        intf->intf_num = -1;
+        intf->intf_num = -1; /* Mark it invalid for now. */
         kref_init(&intf->refcount);
         intf->bmc->id = *device_id;
         intf->si_dev = si_dev;
@@ -2511,20 +2532,22 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
         spin_lock_init(&intf->counter_lock);
         intf->proc_dir = NULL;
 
-        rv = -ENOMEM;
-        spin_lock_irqsave(&interfaces_lock, flags);
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                if (ipmi_interfaces[i] == NULL) {
-                        intf->intf_num = i;
-                        /* Reserve the entry till we are done. */
-                        ipmi_interfaces[i] = IPMI_INVALID_INTERFACE_ENTRY;
-                        rv = 0;
+        mutex_lock(&ipmi_interfaces_mutex);
+        /* Look for a hole in the numbers. */
+        i = 0;
+        link = &ipmi_interfaces;
+        list_for_each_entry_rcu(tintf, &ipmi_interfaces, link) {
+                if (tintf->intf_num != i) {
+                        link = &tintf->link;
                         break;
                 }
+                i++;
         }
-        spin_unlock_irqrestore(&interfaces_lock, flags);
-        if (rv)
-                goto out;
+        /* Add the new interface in numeric order. */
+        if (i == 0)
+                list_add_rcu(&intf->link, &ipmi_interfaces);
+        else
+                list_add_tail_rcu(&intf->link, link);
 
         rv = handlers->start_processing(send_info, intf);
         if (rv)
@@ -2562,16 +2585,14 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
         if (rv) {
                 if (intf->proc_dir)
                         remove_proc_entries(intf);
+                list_del_rcu(&intf->link);
+                mutex_unlock(&ipmi_interfaces_mutex);
+                synchronize_rcu();
                 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);
+                /* After this point the interface is legal to use. */
+                intf->intf_num = i;
+                mutex_unlock(&ipmi_interfaces_mutex);
                 call_smi_watchers(i, intf->si_dev);
         }
 
@@ -2580,26 +2601,14 @@ int ipmi_register_smi(struct ipmi_smi_handlers *handlers,
 
 int ipmi_unregister_smi(ipmi_smi_t intf)
 {
-        int                     i;
         struct ipmi_smi_watcher *w;
-        unsigned long           flags;
 
         ipmi_bmc_unregister(intf);
 
-        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;
-                }
-        }
-        spin_unlock_irqrestore(&interfaces_lock,flags);
-
-        if (i == MAX_IPMI_INTERFACES)
-                return -ENODEV;
+        mutex_lock(&ipmi_interfaces_mutex);
+        list_del_rcu(&intf->link);
+        mutex_unlock(&ipmi_interfaces_mutex);
+        synchronize_rcu();
 
         remove_proc_entries(intf);
 
@@ -2607,14 +2616,9 @@ int ipmi_unregister_smi(ipmi_smi_t intf)
            an interface is gone. */
         down_read(&smi_watchers_sem);
         list_for_each_entry(w, &smi_watchers, link)
-                w->smi_gone(i);
+                w->smi_gone(intf->intf_num);
         up_read(&smi_watchers_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;
 }
@@ -3446,18 +3450,12 @@ static void ipmi_timeout_handler(long timeout_period)
         struct ipmi_recv_msg *msg, *msg2;
         struct ipmi_smi_msg  *smi_msg, *smi_msg2;
         unsigned long        flags;
-        int                  i, j;
+        int                  i;
 
         INIT_LIST_HEAD(&timeouts);
 
-        spin_lock(&interfaces_lock);
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                intf = ipmi_interfaces[i];
-                if (IPMI_INVALID_INTERFACE(intf))
-                        continue;
-                kref_get(&intf->refcount);
-                spin_unlock(&interfaces_lock);
-
+        rcu_read_lock();
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                 /* 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,
@@ -3477,35 +3475,26 @@ static void ipmi_timeout_handler(long timeout_period)
                    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++)
-                        check_msg_timeout(intf, &(intf->seq_table[j]),
-                                          &timeouts, timeout_period, j,
+                for (i = 0; i < IPMI_IPMB_NUM_SEQ; i++)
+                        check_msg_timeout(intf, &(intf->seq_table[i]),
+                                          &timeouts, timeout_period, i,
                                           &flags);
                 spin_unlock_irqrestore(&intf->seq_lock, flags);
 
                 list_for_each_entry_safe(msg, msg2, &timeouts, link)
                         handle_msg_timeout(msg);
-
-                kref_put(&intf->refcount, intf_free);
-                spin_lock(&interfaces_lock);
         }
-        spin_unlock(&interfaces_lock);
+        rcu_read_unlock();
 }
 
 static void ipmi_request_event(void)
 {
         ipmi_smi_t intf;
-        int        i;
-
-        spin_lock(&interfaces_lock);
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                intf = ipmi_interfaces[i];
-                if (IPMI_INVALID_INTERFACE(intf))
-                        continue;
 
+        rcu_read_lock();
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link)
                 intf->handlers->request_events(intf->send_info);
-        }
-        spin_unlock(&interfaces_lock);
+        rcu_read_unlock();
 }
 
 static struct timer_list ipmi_timer;
@@ -3634,7 +3623,6 @@ static void send_panic_events(char *str)
         struct kernel_ipmi_msg            msg;
         ipmi_smi_t                        intf;
         unsigned char                     data[16];
-        int                               i;
         struct ipmi_system_interface_addr *si;
         struct ipmi_addr                  addr;
         struct ipmi_smi_msg               smi_msg;
@@ -3668,9 +3656,9 @@ static void send_panic_events(char *str)
         recv_msg.done = dummy_recv_done_handler;
 
         /* For every registered interface, send the event. */
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                intf = ipmi_interfaces[i];
-                if (IPMI_INVALID_INTERFACE(intf))
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+                if (intf->intf_num == -1)
+                        /* Interface was not ready yet. */
                         continue;
 
                 /* Send the event announcing the panic. */
@@ -3695,13 +3683,14 @@ static void send_panic_events(char *str)
         if (!str) 
                 return;
 
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
+        /* For every registered interface, send the event. */
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
                 char                  *p = str;
                 struct ipmi_ipmb_addr *ipmb;
                 int                   j;
 
-                intf = ipmi_interfaces[i];
-                if (IPMI_INVALID_INTERFACE(intf))
+                if (intf->intf_num == -1)
+                        /* Interface was not ready yet. */
                         continue;
 
                 /* First job here is to figure out where to send the
@@ -3827,7 +3816,6 @@ static int panic_event(struct notifier_block *this,
                        unsigned long         event,
                        void                  *ptr)
 {
-        int        i;
         ipmi_smi_t intf;
 
         if (has_panicked)
@@ -3835,9 +3823,9 @@ static int panic_event(struct notifier_block *this,
         has_panicked = 1;
 
         /* For every registered interface, set it to run to completion. */
-        for (i = 0; i < MAX_IPMI_INTERFACES; i++) {
-                intf = ipmi_interfaces[i];
-                if (IPMI_INVALID_INTERFACE(intf))
+        list_for_each_entry_rcu(intf, &ipmi_interfaces, link) {
+                if (intf->intf_num == -1)
+                        /* Interface was not ready yet. */
                         continue;
 
                 intf->handlers->set_run_to_completion(intf->send_info, 1);
@@ -3858,7 +3846,6 @@ static struct notifier_block panic_block = {
 
 static int ipmi_init_msghandler(void)
 {
-        int i;
         int rv;
 
         if (initialized)
@@ -3873,9 +3860,6 @@ 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++)
-                ipmi_interfaces[i] = NULL;
-
 #ifdef CONFIG_PROC_FS
         proc_ipmi_root = proc_mkdir("ipmi", NULL);
         if (!proc_ipmi_root) {