Merge branch 'acpi-ipmi'

* acpi-ipmi:
  ACPI / IPMI: Cleanup coding styles
  ACPI / IPMI: Cleanup some Kconfig codes
  ACPI / IPMI: Cleanup some inclusion codes
  ACPI / IPMI: Cleanup some initialization codes
  ACPI / IPMI: Cleanup several acpi_ipmi_device members
  ACPI / IPMI: Add reference counting for ACPI IPMI transfers
  ACPI / IPMI: Use global IPMI operation region handler
  ACPI / IPMI: Fix race caused by the unprotected ACPI IPMI user
  ACPI / IPMI: Fix race caused by the timed out ACPI IPMI transfers
  ACPI / IPMI: Fix race caused by the unprotected ACPI IPMI transfers
  ACPI / IPMI: Fix potential response buffer overflow

2 files changed, 358 insertions, 225 deletions

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 10e399f..589da05 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -158,9 +158,10 @@ config ACPI_PROCESSOR
 
 	  To compile this driver as a module, choose M here:
 	  the module will be called processor.
+
 config ACPI_IPMI
 	tristate "IPMI"
-	depends on IPMI_SI && IPMI_HANDLER
+	depends on IPMI_SI
 	default n
 	help
 	  This driver enables the ACPI to access the BMC controller. And it
diff --git a/drivers/acpi/acpi_ipmi.c b/drivers/acpi/acpi_ipmi.c
index a6977e1..ac0f52f 100644
--- a/drivers/acpi/acpi_ipmi.c
+++ b/drivers/acpi/acpi_ipmi.c
@@ -1,8 +1,9 @@
 /*
  *  acpi_ipmi.c - ACPI IPMI opregion
  *
- *  Copyright (C) 2010 Intel Corporation
- *  Copyright (C) 2010 Zhao Yakui <yakui.zhao@intel.com>
+ *  Copyright (C) 2010, 2013 Intel Corporation
+ *    Author: Zhao Yakui <yakui.zhao@intel.com>
+ *            Lv Zheng <lv.zheng@intel.com>
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *
@@ -23,60 +24,58 @@
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
 
-#include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/init.h>
-#include <linux/types.h>
-#include <linux/delay.h>
-#include <linux/proc_fs.h>
-#include <linux/seq_file.h>
-#include <linux/interrupt.h>
-#include <linux/list.h>
-#include <linux/spinlock.h>
-#include <linux/io.h>
-#include <acpi/acpi_bus.h>
-#include <acpi/acpi_drivers.h>
+#include <linux/acpi.h>
 #include <linux/ipmi.h>
-#include <linux/device.h>
-#include <linux/pnp.h>
 #include <linux/spinlock.h>
 
 MODULE_AUTHOR("Zhao Yakui");
 MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
 MODULE_LICENSE("GPL");
 
-#define IPMI_FLAGS_HANDLER_INSTALL	0
-
 #define ACPI_IPMI_OK			0
 #define ACPI_IPMI_TIMEOUT		0x10
 #define ACPI_IPMI_UNKNOWN		0x07
 /* the IPMI timeout is 5s */
-#define IPMI_TIMEOUT			(5 * HZ)
+#define IPMI_TIMEOUT			(5000)
+#define ACPI_IPMI_MAX_MSG_LENGTH	64
 
 struct acpi_ipmi_device {
 	/* the device list attached to driver_data.ipmi_devices */
 	struct list_head head;
+
 	/* the IPMI request message list */
 	struct list_head tx_msg_list;
-	spinlock_t	tx_msg_lock;
+
+	spinlock_t tx_msg_lock;
 	acpi_handle handle;
-	struct pnp_dev *pnp_dev;
-	ipmi_user_t	user_interface;
+	struct device *dev;
+	ipmi_user_t user_interface;
 	int ipmi_ifnum; /* IPMI interface number */
 	long curr_msgid;
-	unsigned long flags;
-	struct ipmi_smi_info smi_data;
+	bool dead;
+	struct kref kref;
 };
 
 struct ipmi_driver_data {
-	struct list_head	ipmi_devices;
-	struct ipmi_smi_watcher	bmc_events;
-	struct ipmi_user_hndl	ipmi_hndlrs;
-	struct mutex		ipmi_lock;
+	struct list_head ipmi_devices;
+	struct ipmi_smi_watcher bmc_events;
+	struct ipmi_user_hndl ipmi_hndlrs;
+	struct mutex ipmi_lock;
+
+	/*
+	 * NOTE: IPMI System Interface Selection
+	 * There is no system interface specified by the IPMI operation
+	 * region access.  We try to select one system interface with ACPI
+	 * handle set.  IPMI messages passed from the ACPI codes are sent
+	 * to this selected global IPMI system interface.
+	 */
+	struct acpi_ipmi_device *selected_smi;
 };
 
 struct acpi_ipmi_msg {
 	struct list_head head;
+
 	/*
 	 * General speaking the addr type should be SI_ADDR_TYPE. And
 	 * the addr channel should be BMC.
@@ -86,30 +85,31 @@ struct acpi_ipmi_msg {
 	 */
 	struct ipmi_addr addr;
 	long tx_msgid;
+
 	/* it is used to track whether the IPMI message is finished */
 	struct completion tx_complete;
+
 	struct kernel_ipmi_msg tx_message;
-	int	msg_done;
-	/* tx data . And copy it from ACPI object buffer */
-	u8	tx_data[64];
-	int	tx_len;
-	u8	rx_data[64];
-	int	rx_len;
+	int msg_done;
+
+	/* tx/rx data . And copy it from/to ACPI object buffer */
+	u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
+	u8 rx_len;
+
 	struct acpi_ipmi_device *device;
+	struct kref kref;
 };
 
 /* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
 struct acpi_ipmi_buffer {
 	u8 status;
 	u8 length;
-	u8 data[64];
+	u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
 };
 
 static void ipmi_register_bmc(int iface, struct device *dev);
 static void ipmi_bmc_gone(int iface);
 static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
-static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device);
-static void acpi_remove_ipmi_device(struct acpi_ipmi_device *ipmi_device);
 
 static struct ipmi_driver_data driver_data = {
 	.ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
@@ -121,29 +121,142 @@ static struct ipmi_driver_data driver_data = {
 	.ipmi_hndlrs = {
 		.ipmi_recv_hndl = ipmi_msg_handler,
 	},
+	.ipmi_lock = __MUTEX_INITIALIZER(driver_data.ipmi_lock)
 };
 
-static struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi)
+static struct acpi_ipmi_device *
+ipmi_dev_alloc(int iface, struct device *dev, acpi_handle handle)
+{
+	struct acpi_ipmi_device *ipmi_device;
+	int err;
+	ipmi_user_t user;
+
+	ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);
+	if (!ipmi_device)
+		return NULL;
+
+	kref_init(&ipmi_device->kref);
+	INIT_LIST_HEAD(&ipmi_device->head);
+	INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
+	spin_lock_init(&ipmi_device->tx_msg_lock);
+	ipmi_device->handle = handle;
+	ipmi_device->dev = get_device(dev);
+	ipmi_device->ipmi_ifnum = iface;
+
+	err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
+			       ipmi_device, &user);
+	if (err) {
+		put_device(dev);
+		kfree(ipmi_device);
+		return NULL;
+	}
+	ipmi_device->user_interface = user;
+
+	return ipmi_device;
+}
+
+static void ipmi_dev_release(struct acpi_ipmi_device *ipmi_device)
+{
+	ipmi_destroy_user(ipmi_device->user_interface);
+	put_device(ipmi_device->dev);
+	kfree(ipmi_device);
+}
+
+static void ipmi_dev_release_kref(struct kref *kref)
+{
+	struct acpi_ipmi_device *ipmi =
+		container_of(kref, struct acpi_ipmi_device, kref);
+
+	ipmi_dev_release(ipmi);
+}
+
+static void __ipmi_dev_kill(struct acpi_ipmi_device *ipmi_device)
+{
+	list_del(&ipmi_device->head);
+	if (driver_data.selected_smi == ipmi_device)
+		driver_data.selected_smi = NULL;
+
+	/*
+	 * Always setting dead flag after deleting from the list or
+	 * list_for_each_entry() codes must get changed.
+	 */
+	ipmi_device->dead = true;
+}
+
+static struct acpi_ipmi_device *acpi_ipmi_dev_get(void)
+{
+	struct acpi_ipmi_device *ipmi_device = NULL;
+
+	mutex_lock(&driver_data.ipmi_lock);
+	if (driver_data.selected_smi) {
+		ipmi_device = driver_data.selected_smi;
+		kref_get(&ipmi_device->kref);
+	}
+	mutex_unlock(&driver_data.ipmi_lock);
+
+	return ipmi_device;
+}
+
+static void acpi_ipmi_dev_put(struct acpi_ipmi_device *ipmi_device)
+{
+	kref_put(&ipmi_device->kref, ipmi_dev_release_kref);
+}
+
+static struct acpi_ipmi_msg *ipmi_msg_alloc(void)
 {
+	struct acpi_ipmi_device *ipmi;
 	struct acpi_ipmi_msg *ipmi_msg;
-	struct pnp_dev *pnp_dev = ipmi->pnp_dev;
+
+	ipmi = acpi_ipmi_dev_get();
+	if (!ipmi)
+		return NULL;
 
 	ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
-	if (!ipmi_msg)	{
-		dev_warn(&pnp_dev->dev, "Can't allocate memory for ipmi_msg\n");
+	if (!ipmi_msg) {
+		acpi_ipmi_dev_put(ipmi);
 		return NULL;
 	}
+
+	kref_init(&ipmi_msg->kref);
 	init_completion(&ipmi_msg->tx_complete);
 	INIT_LIST_HEAD(&ipmi_msg->head);
 	ipmi_msg->device = ipmi;
+	ipmi_msg->msg_done = ACPI_IPMI_UNKNOWN;
+
 	return ipmi_msg;
 }
 
-#define		IPMI_OP_RGN_NETFN(offset)	((offset >> 8) & 0xff)
-#define		IPMI_OP_RGN_CMD(offset)		(offset & 0xff)
-static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
-				acpi_physical_address address,
-				acpi_integer *value)
+static void ipmi_msg_release(struct acpi_ipmi_msg *tx_msg)
+{
+	acpi_ipmi_dev_put(tx_msg->device);
+	kfree(tx_msg);
+}
+
+static void ipmi_msg_release_kref(struct kref *kref)
+{
+	struct acpi_ipmi_msg *tx_msg =
+		container_of(kref, struct acpi_ipmi_msg, kref);
+
+	ipmi_msg_release(tx_msg);
+}
+
+static struct acpi_ipmi_msg *acpi_ipmi_msg_get(struct acpi_ipmi_msg *tx_msg)
+{
+	kref_get(&tx_msg->kref);
+
+	return tx_msg;
+}
+
+static void acpi_ipmi_msg_put(struct acpi_ipmi_msg *tx_msg)
+{
+	kref_put(&tx_msg->kref, ipmi_msg_release_kref);
+}
+
+#define IPMI_OP_RGN_NETFN(offset)	((offset >> 8) & 0xff)
+#define IPMI_OP_RGN_CMD(offset)		(offset & 0xff)
+static int acpi_format_ipmi_request(struct acpi_ipmi_msg *tx_msg,
+				    acpi_physical_address address,
+				    acpi_integer *value)
 {
 	struct kernel_ipmi_msg *msg;
 	struct acpi_ipmi_buffer *buffer;
@@ -151,21 +264,31 @@ static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
 	unsigned long flags;
 
 	msg = &tx_msg->tx_message;
+
 	/*
 	 * IPMI network function and command are encoded in the address
 	 * within the IPMI OpRegion; see ACPI 4.0, sec 5.5.2.4.3.
 	 */
 	msg->netfn = IPMI_OP_RGN_NETFN(address);
 	msg->cmd = IPMI_OP_RGN_CMD(address);
-	msg->data = tx_msg->tx_data;
+	msg->data = tx_msg->data;
+
 	/*
 	 * value is the parameter passed by the IPMI opregion space handler.
 	 * It points to the IPMI request message buffer
 	 */
 	buffer = (struct acpi_ipmi_buffer *)value;
+
 	/* copy the tx message data */
+	if (buffer->length > ACPI_IPMI_MAX_MSG_LENGTH) {
+		dev_WARN_ONCE(tx_msg->device->dev, true,
+			      "Unexpected request (msg len %d).\n",
+			      buffer->length);
+		return -EINVAL;
+	}
 	msg->data_len = buffer->length;
-	memcpy(tx_msg->tx_data, buffer->data, msg->data_len);
+	memcpy(tx_msg->data, buffer->data, msg->data_len);
+
 	/*
 	 * now the default type is SYSTEM_INTERFACE and channel type is BMC.
 	 * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
@@ -179,14 +302,17 @@ static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
 
 	/* Get the msgid */
 	device = tx_msg->device;
+
 	spin_lock_irqsave(&device->tx_msg_lock, flags);
 	device->curr_msgid++;
 	tx_msg->tx_msgid = device->curr_msgid;
 	spin_unlock_irqrestore(&device->tx_msg_lock, flags);
+
+	return 0;
 }
 
 static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
-		acpi_integer *value, int rem_time)
+				      acpi_integer *value)
 {
 	struct acpi_ipmi_buffer *buffer;
 
@@ -195,110 +321,158 @@ static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
 	 * IPMI message returned by IPMI command.
 	 */
 	buffer = (struct acpi_ipmi_buffer *)value;
-	if (!rem_time && !msg->msg_done) {
-		buffer->status = ACPI_IPMI_TIMEOUT;
-		return;
-	}
+
 	/*
-	 * If the flag of msg_done is not set or the recv length is zero, it
-	 * means that the IPMI command is not executed correctly.
-	 * The status code will be ACPI_IPMI_UNKNOWN.
+	 * If the flag of msg_done is not set, it means that the IPMI command is
+	 * not executed correctly.
 	 */
-	if (!msg->msg_done || !msg->rx_len) {
-		buffer->status = ACPI_IPMI_UNKNOWN;
+	buffer->status = msg->msg_done;
+	if (msg->msg_done != ACPI_IPMI_OK)
 		return;
-	}
+
 	/*
 	 * If the IPMI response message is obtained correctly, the status code
 	 * will be ACPI_IPMI_OK
 	 */
-	buffer->status = ACPI_IPMI_OK;
 	buffer->length = msg->rx_len;
-	memcpy(buffer->data, msg->rx_data, msg->rx_len);
+	memcpy(buffer->data, msg->data, msg->rx_len);
 }
 
 static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
 {
-	struct acpi_ipmi_msg *tx_msg, *temp;
-	int count = HZ / 10;
-	struct pnp_dev *pnp_dev = ipmi->pnp_dev;
+	struct acpi_ipmi_msg *tx_msg;
+	unsigned long flags;
+
+	/*
+	 * NOTE: On-going ipmi_recv_msg
+	 * ipmi_msg_handler() may still be invoked by ipmi_si after
+	 * flushing.  But it is safe to do a fast flushing on module_exit()
+	 * without waiting for all ipmi_recv_msg(s) to complete from
+	 * ipmi_msg_handler() as it is ensured by ipmi_si that all
+	 * ipmi_recv_msg(s) are freed after invoking ipmi_destroy_user().
+	 */
+	spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
+	while (!list_empty(&ipmi->tx_msg_list)) {
+		tx_msg = list_first_entry(&ipmi->tx_msg_list,
+					  struct acpi_ipmi_msg,
+					  head);
+		list_del(&tx_msg->head);
+		spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
 
-	list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
 		/* wake up the sleep thread on the Tx msg */
 		complete(&tx_msg->tx_complete);
+		acpi_ipmi_msg_put(tx_msg);
+		spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
 	}
+	spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
+}
+
+static void ipmi_cancel_tx_msg(struct acpi_ipmi_device *ipmi,
+			       struct acpi_ipmi_msg *msg)
+{
+	struct acpi_ipmi_msg *tx_msg, *temp;
+	bool msg_found = false;
+	unsigned long flags;
 
-	/* wait for about 100ms to flush the tx message list */
-	while (count--) {
-		if (list_empty(&ipmi->tx_msg_list))
+	spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
+	list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
+		if (msg == tx_msg) {
+			msg_found = true;
+			list_del(&tx_msg->head);
 			break;
-		schedule_timeout(1);
+		}
 	}
-	if (!list_empty(&ipmi->tx_msg_list))
-		dev_warn(&pnp_dev->dev, "tx msg list is not NULL\n");
+	spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
+
+	if (msg_found)
+		acpi_ipmi_msg_put(tx_msg);
 }
 
 static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
 {
 	struct acpi_ipmi_device *ipmi_device = user_msg_data;
-	int msg_found = 0;
-	struct acpi_ipmi_msg *tx_msg;
-	struct pnp_dev *pnp_dev = ipmi_device->pnp_dev;
+	bool msg_found = false;
+	struct acpi_ipmi_msg *tx_msg, *temp;
+	struct device *dev = ipmi_device->dev;
 	unsigned long flags;
 
 	if (msg->user != ipmi_device->user_interface) {
-		dev_warn(&pnp_dev->dev, "Unexpected response is returned. "
-			"returned user %p, expected user %p\n",
-			msg->user, ipmi_device->user_interface);
-		ipmi_free_recv_msg(msg);
-		return;
+		dev_warn(dev,
+			 "Unexpected response is returned. returned user %p, expected user %p\n",
+			 msg->user, ipmi_device->user_interface);
+		goto out_msg;
 	}
+
 	spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
-	list_for_each_entry(tx_msg, &ipmi_device->tx_msg_list, head) {
+	list_for_each_entry_safe(tx_msg, temp, &ipmi_device->tx_msg_list, head) {
 		if (msg->msgid == tx_msg->tx_msgid) {
-			msg_found = 1;
+			msg_found = true;
+			list_del(&tx_msg->head);
 			break;
 		}
 	}
-
 	spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
+
 	if (!msg_found) {
-		dev_warn(&pnp_dev->dev, "Unexpected response (msg id %ld) is "
-			"returned.\n", msg->msgid);
-		ipmi_free_recv_msg(msg);
-		return;
+		dev_warn(dev,
+			 "Unexpected response (msg id %ld) is returned.\n",
+			 msg->msgid);
+		goto out_msg;
 	}
 
-	if (msg->msg.data_len) {
-		/* copy the response data to Rx_data buffer */
-		memcpy(tx_msg->rx_data, msg->msg_data, msg->msg.data_len);
-		tx_msg->rx_len = msg->msg.data_len;
-		tx_msg->msg_done = 1;
+	/* copy the response data to Rx_data buffer */
+	if (msg->msg.data_len > ACPI_IPMI_MAX_MSG_LENGTH) {
+		dev_WARN_ONCE(dev, true,
+			      "Unexpected response (msg len %d).\n",
+			      msg->msg.data_len);
+		goto out_comp;
 	}
+
+	/* response msg is an error msg */
+	msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
+	if (msg->recv_type == IPMI_RESPONSE_RECV_TYPE &&
+	    msg->msg.data_len == 1) {
+		if (msg->msg.data[0] == IPMI_TIMEOUT_COMPLETION_CODE) {
+			dev_WARN_ONCE(dev, true,
+				      "Unexpected response (timeout).\n");
+			tx_msg->msg_done = ACPI_IPMI_TIMEOUT;
+		}
+		goto out_comp;
+	}
+
+	tx_msg->rx_len = msg->msg.data_len;
+	memcpy(tx_msg->data, msg->msg.data, tx_msg->rx_len);
+	tx_msg->msg_done = ACPI_IPMI_OK;
+
+out_comp:
 	complete(&tx_msg->tx_complete);
+	acpi_ipmi_msg_put(tx_msg);
+out_msg:
 	ipmi_free_recv_msg(msg);
-};
+}
 
 static void ipmi_register_bmc(int iface, struct device *dev)
 {
 	struct acpi_ipmi_device *ipmi_device, *temp;
-	struct pnp_dev *pnp_dev;
-	ipmi_user_t		user;
 	int err;
 	struct ipmi_smi_info smi_data;
 	acpi_handle handle;
 
 	err = ipmi_get_smi_info(iface, &smi_data);
-
 	if (err)
 		return;
 
-	if (smi_data.addr_src != SI_ACPI) {
-		put_device(smi_data.dev);
-		return;
-	}
-
+	if (smi_data.addr_src != SI_ACPI)
+		goto err_ref;
 	handle = smi_data.addr_info.acpi_info.acpi_handle;
+	if (!handle)
+		goto err_ref;
+
+	ipmi_device = ipmi_dev_alloc(iface, smi_data.dev, handle);
+	if (!ipmi_device) {
+		dev_warn(smi_data.dev, "Can't create IPMI user interface\n");
+		goto err_ref;
+	}
 
 	mutex_lock(&driver_data.ipmi_lock);
 	list_for_each_entry(temp, &driver_data.ipmi_devices, head) {
@@ -307,34 +481,20 @@ static void ipmi_register_bmc(int iface, struct device *dev)
 		 * to the device list, don't add it again.
 		 */
 		if (temp->handle == handle)
-			goto out;
+			goto err_lock;
 	}
-
-	ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);
-
-	if (!ipmi_device)
-		goto out;
-
-	pnp_dev = to_pnp_dev(smi_data.dev);
-	ipmi_device->handle = handle;
-	ipmi_device->pnp_dev = pnp_dev;
-
-	err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
-					ipmi_device, &user);
-	if (err) {
-		dev_warn(&pnp_dev->dev, "Can't create IPMI user interface\n");
-		kfree(ipmi_device);
-		goto out;
-	}
-	acpi_add_ipmi_device(ipmi_device);
-	ipmi_device->user_interface = user;
-	ipmi_device->ipmi_ifnum = iface;
+	if (!driver_data.selected_smi)
+		driver_data.selected_smi = ipmi_device;
+	list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
 	mutex_unlock(&driver_data.ipmi_lock);
-	memcpy(&ipmi_device->smi_data, &smi_data, sizeof(struct ipmi_smi_info));
+
+	put_device(smi_data.dev);
 	return;
 
-out:
+err_lock:
 	mutex_unlock(&driver_data.ipmi_lock);
+	ipmi_dev_release(ipmi_device);
+err_ref:
 	put_device(smi_data.dev);
 	return;
 }
@@ -342,23 +502,29 @@ out:
 static void ipmi_bmc_gone(int iface)
 {
 	struct acpi_ipmi_device *ipmi_device, *temp;
+	bool dev_found = false;
 
 	mutex_lock(&driver_data.ipmi_lock);
 	list_for_each_entry_safe(ipmi_device, temp,
-				&driver_data.ipmi_devices, head) {
-		if (ipmi_device->ipmi_ifnum != iface)
-			continue;
-
-		acpi_remove_ipmi_device(ipmi_device);
-		put_device(ipmi_device->smi_data.dev);
-		kfree(ipmi_device);
-		break;
+				 &driver_data.ipmi_devices, head) {
+		if (ipmi_device->ipmi_ifnum != iface) {
+			dev_found = true;
+			__ipmi_dev_kill(ipmi_device);
+			break;
+		}
 	}
+	if (!driver_data.selected_smi)
+		driver_data.selected_smi = list_first_entry_or_null(
+					&driver_data.ipmi_devices,
+					struct acpi_ipmi_device, head);
 	mutex_unlock(&driver_data.ipmi_lock);
+
+	if (dev_found) {
+		ipmi_flush_tx_msg(ipmi_device);
+		acpi_ipmi_dev_put(ipmi_device);
+	}
 }
-/* --------------------------------------------------------------------------
- *			Address Space Management
- * -------------------------------------------------------------------------- */
+
 /*
  * This is the IPMI opregion space handler.
  * @function: indicates the read/write. In fact as the IPMI message is driven
@@ -371,17 +537,17 @@ static void ipmi_bmc_gone(int iface)
  *	     the response IPMI message returned by IPMI command.
  * @handler_context: IPMI device context.
  */
-
 static acpi_status
 acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
-		      u32 bits, acpi_integer *value,
-		      void *handler_context, void *region_context)
+			u32 bits, acpi_integer *value,
+			void *handler_context, void *region_context)
 {
 	struct acpi_ipmi_msg *tx_msg;
-	struct acpi_ipmi_device *ipmi_device = handler_context;
-	int err, rem_time;
+	struct acpi_ipmi_device *ipmi_device;
+	int err;
 	acpi_status status;
 	unsigned long flags;
+
 	/*
 	 * IPMI opregion message.
 	 * IPMI message is firstly written to the BMC and system software
@@ -391,118 +557,75 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
 	if ((function & ACPI_IO_MASK) == ACPI_READ)
 		return AE_TYPE;
 
-	if (!ipmi_device->user_interface)
+	tx_msg = ipmi_msg_alloc();
+	if (!tx_msg)
 		return AE_NOT_EXIST;
+	ipmi_device = tx_msg->device;
 
-	tx_msg = acpi_alloc_ipmi_msg(ipmi_device);
-	if (!tx_msg)
-		return AE_NO_MEMORY;
+	if (acpi_format_ipmi_request(tx_msg, address, value) != 0) {
+		ipmi_msg_release(tx_msg);
+		return AE_TYPE;
+	}
 
-	acpi_format_ipmi_msg(tx_msg, address, value);
+	acpi_ipmi_msg_get(tx_msg);
+	mutex_lock(&driver_data.ipmi_lock);
+	/* Do not add a tx_msg that can not be flushed. */
+	if (ipmi_device->dead) {
+		mutex_unlock(&driver_data.ipmi_lock);
+		ipmi_msg_release(tx_msg);
+		return AE_NOT_EXIST;
+	}
 	spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
 	list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
 	spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
+	mutex_unlock(&driver_data.ipmi_lock);
+
 	err = ipmi_request_settime(ipmi_device->user_interface,
-					&tx_msg->addr,
-					tx_msg->tx_msgid,
-					&tx_msg->tx_message,
-					NULL, 0, 0, 0);
+				   &tx_msg->addr,
+				   tx_msg->tx_msgid,
+				   &tx_msg->tx_message,
+				   NULL, 0, 0, IPMI_TIMEOUT);
 	if (err) {
 		status = AE_ERROR;
-		goto end_label;
+		goto out_msg;
 	}
-	rem_time = wait_for_completion_timeout(&tx_msg->tx_complete,
-					IPMI_TIMEOUT);
-	acpi_format_ipmi_response(tx_msg, value, rem_time);
+	wait_for_completion(&tx_msg->tx_complete);
+
+	acpi_format_ipmi_response(tx_msg, value);
 	status = AE_OK;
 
-end_label:
-	spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
-	list_del(&tx_msg->head);
-	spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
-	kfree(tx_msg);
+out_msg:
+	ipmi_cancel_tx_msg(ipmi_device, tx_msg);
+	acpi_ipmi_msg_put(tx_msg);
 	return status;
 }
 
-static void ipmi_remove_space_handler(struct acpi_ipmi_device *ipmi)
-{
-	if (!test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
-		return;
-
-	acpi_remove_address_space_handler(ipmi->handle,
-				ACPI_ADR_SPACE_IPMI, &acpi_ipmi_space_handler);
-
-	clear_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
-}
-
-static int ipmi_install_space_handler(struct acpi_ipmi_device *ipmi)
+static int __init acpi_ipmi_init(void)
 {
+	int result;
 	acpi_status status;
 
-	if (test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
+	if (acpi_disabled)
 		return 0;
 
-	status = acpi_install_address_space_handler(ipmi->handle,
+	status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
 						    ACPI_ADR_SPACE_IPMI,
 						    &acpi_ipmi_space_handler,
-						    NULL, ipmi);
+						    NULL, NULL);
 	if (ACPI_FAILURE(status)) {
-		struct pnp_dev *pnp_dev = ipmi->pnp_dev;
-		dev_warn(&pnp_dev->dev, "Can't register IPMI opregion space "
-			"handle\n");
+		pr_warn("Can't register IPMI opregion space handle\n");
 		return -EINVAL;
 	}
-	set_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
-	return 0;
-}
-
-static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device)
-{
-
-	INIT_LIST_HEAD(&ipmi_device->head);
-
-	spin_lock_init(&ipmi_device->tx_msg_lock);
-	INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
-	ipmi_install_space_handler(ipmi_device);
-
-	list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
-}
-
-static void acpi_remove_ipmi_device(struct acpi_ipmi_device *ipmi_device)
-{
-	/*
-	 * If the IPMI user interface is created, it should be
-	 * destroyed.
-	 */
-	if (ipmi_device->user_interface) {
-		ipmi_destroy_user(ipmi_device->user_interface);
-		ipmi_device->user_interface = NULL;
-	}
-	/* flush the Tx_msg list */
-	if (!list_empty(&ipmi_device->tx_msg_list))
-		ipmi_flush_tx_msg(ipmi_device);
-
-	list_del(&ipmi_device->head);
-	ipmi_remove_space_handler(ipmi_device);
-}
-
-static int __init acpi_ipmi_init(void)
-{
-	int result = 0;
-
-	if (acpi_disabled)
-		return result;
-
-	mutex_init(&driver_data.ipmi_lock);
-
 	result = ipmi_smi_watcher_register(&driver_data.bmc_events);
+	if (result)
+		pr_err("Can't register IPMI system interface watcher\n");
 
 	return result;
 }
 
 static void __exit acpi_ipmi_exit(void)
 {
-	struct acpi_ipmi_device *ipmi_device, *temp;
+	struct acpi_ipmi_device *ipmi_device;
 
 	if (acpi_disabled)
 		return;
@@ -516,13 +639,22 @@ static void __exit acpi_ipmi_exit(void)
 	 * handler and free it.
 	 */
 	mutex_lock(&driver_data.ipmi_lock);
-	list_for_each_entry_safe(ipmi_device, temp,
-				&driver_data.ipmi_devices, head) {
-		acpi_remove_ipmi_device(ipmi_device);
-		put_device(ipmi_device->smi_data.dev);
-		kfree(ipmi_device);
+	while (!list_empty(&driver_data.ipmi_devices)) {
+		ipmi_device = list_first_entry(&driver_data.ipmi_devices,
+					       struct acpi_ipmi_device,
+					       head);
+		__ipmi_dev_kill(ipmi_device);
+		mutex_unlock(&driver_data.ipmi_lock);
+
+		ipmi_flush_tx_msg(ipmi_device);
+		acpi_ipmi_dev_put(ipmi_device);
+
+		mutex_lock(&driver_data.ipmi_lock);
 	}
 	mutex_unlock(&driver_data.ipmi_lock);
+	acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
+					  ACPI_ADR_SPACE_IPMI,
+					  &acpi_ipmi_space_handler);
 }
 
 module_init(acpi_ipmi_init);