ipmi: Prefer ACPI system interfaces over SMBIOS ones

The recent changes to add SMBIOS (DMI) IPMI interfaces as platform
devices caused DMI to be selected before ACPI, causing ACPI type
of operations to not work.
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_si_intf.c

@@ -3425,7 +3425,7 @@ static inline void wait_for_timer_and_thread(struct smi_info *smi_info)
 		del_timer_sync(&smi_info->si_timer);
 }
 
-static int is_new_interface(struct smi_info *info)
+static struct smi_info *find_dup_si(struct smi_info *info)
 {
 	struct smi_info *e;
 
@@ -3440,24 +3440,36 @@ static int is_new_interface(struct smi_info *info)
 			 */
 			if (info->slave_addr && !e->slave_addr)
 				e->slave_addr = info->slave_addr;
-			return 0;
+			return e;
 		}
 	}
 
-	return 1;
+	return NULL;
 }
 
 static int add_smi(struct smi_info *new_smi)
 {
 	int rv = 0;
+	struct smi_info *dup;
 
 	mutex_lock(&smi_infos_lock);
-	if (!is_new_interface(new_smi)) {
-		pr_info(PFX "%s-specified %s state machine: duplicate\n",
-			ipmi_addr_src_to_str(new_smi->addr_source),
-			si_to_str[new_smi->si_type]);
-		rv = -EBUSY;
-		goto out_err;
+	dup = find_dup_si(new_smi);
+	if (dup) {
+		if (new_smi->addr_source == SI_ACPI &&
+		    dup->addr_source == SI_SMBIOS) {
+			/* We prefer ACPI over SMBIOS. */
+			dev_info(dup->dev,
+				 "Removing SMBIOS-specified %s state machine in favor of ACPI\n",
+				 si_to_str[new_smi->si_type]);
+			cleanup_one_si(dup);
+		} else {
+			dev_info(new_smi->dev,
+				 "%s-specified %s state machine: duplicate\n",
+				 ipmi_addr_src_to_str(new_smi->addr_source),
+				 si_to_str[new_smi->si_type]);
+			rv = -EBUSY;
+			goto out_err;
+		}
 	}
 
 	pr_info(PFX "Adding %s-specified %s state machine\n",
@@ -3866,7 +3878,8 @@ static void cleanup_one_si(struct smi_info *to_clean)
 		poll(to_clean);
 		schedule_timeout_uninterruptible(1);
 	}
-	disable_si_irq(to_clean, false);
+	if (to_clean->handlers)
+		disable_si_irq(to_clean, false);
 	while (to_clean->curr_msg || (to_clean->si_state != SI_NORMAL)) {
 		poll(to_clean);
 		schedule_timeout_uninterruptible(1);