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ACPI / IPMI: Add reference counting for ACPI IPMI transfers
This patch adds reference counting for ACPI IPMI transfers to tune the
locking granularity of tx_msg_lock.
This patch also makes the whole acpi_ipmi module's coding style consistent
by using reference counting for all its objects (i.e., acpi_ipmi_device and
acpi_ipmi_msg).
The acpi_ipmi_msg handling is re-designed using referece counting.
1. tx_msg is always unlinked before complete(), so that it is safe to put
complete() out side of tx_msg_lock.
2. tx_msg reference counters are incremented before calling
ipmi_request_settime() and tx_msg_lock protection is added to
ipmi_cancel_tx_msg() so that a complete() can be safely called in
parellel with tx_msg unlinking in failure cases.
3. tx_msg holds a reference to acpi_ipmi_device so that it can be flushed
and freed in the contexts other than acpi_ipmi_space_handler().
The lockdep_chains shows all acpi_ipmi locks are leaf locks after the
tuning:
1. ipmi_lock is always leaf:
irq_context: 0
[ffffffff81a943f8] smi_watchers_mutex
[ffffffffa06eca60] driver_data.ipmi_lock
irq_context: 0
[ffffffff82767b40] &buffer->mutex
[ffffffffa00a6678] s_active#103
[ffffffffa06eca60] driver_data.ipmi_lock
2. without this patch applied, lock used by complete() is held after
holding tx_msg_lock:
irq_context: 0
[ffffffff82767b40] &buffer->mutex
[ffffffffa00a6678] s_active#103
[ffffffffa06ecce8] &(&ipmi_device->tx_msg_lock)->rlock
irq_context: 1
[ffffffffa06ecce8] &(&ipmi_device->tx_msg_lock)->rlock
irq_context: 1
[ffffffffa06ecce8] &(&ipmi_device->tx_msg_lock)->rlock
[ffffffffa06eccf0] &x->wait#25
irq_context: 1
[ffffffffa06ecce8] &(&ipmi_device->tx_msg_lock)->rlock
[ffffffffa06eccf0] &x->wait#25
[ffffffff81e36620] &p->pi_lock
irq_context: 1
[ffffffffa06ecce8] &(&ipmi_device->tx_msg_lock)->rlock
[ffffffffa06eccf0] &x->wait#25
[ffffffff81e36620] &p->pi_lock
[ffffffff81e5d0a8] &rq->lock
3. with this patch applied, tx_msg_lock is always leaf:
irq_context: 0
[ffffffff82767b40] &buffer->mutex
[ffffffffa00a66d8] s_active#107
[ffffffffa07ecdc8] &(&ipmi_device->tx_msg_lock)->rlock
irq_context: 1
[ffffffffa07ecdc8] &(&ipmi_device->tx_msg_lock)->rlock
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Reviewed-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Lv Zheng
Rafael J. Wysocki
parent
e96a94edd7
commit
7b98447722
@ -104,6 +104,7 @@ struct acpi_ipmi_msg {
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u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
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u8 rx_len;
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struct acpi_ipmi_device *device;
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struct kref kref;
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};
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/* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
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@ -208,16 +209,20 @@ static void acpi_ipmi_dev_put(struct acpi_ipmi_device *ipmi_device)
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kref_put(&ipmi_device->kref, ipmi_dev_release_kref);
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}
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static struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi)
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static struct acpi_ipmi_msg *ipmi_msg_alloc(void)
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{
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struct acpi_ipmi_device *ipmi;
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struct acpi_ipmi_msg *ipmi_msg;
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struct pnp_dev *pnp_dev = ipmi->pnp_dev;
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ipmi = acpi_ipmi_dev_get();
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if (!ipmi)
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return NULL;
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ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
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if (!ipmi_msg) {
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dev_warn(&pnp_dev->dev, "Can't allocate memory for ipmi_msg\n");
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if (!ipmi_msg) {
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acpi_ipmi_dev_put(ipmi);
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return NULL;
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}
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kref_init(&ipmi_msg->kref);
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init_completion(&ipmi_msg->tx_complete);
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INIT_LIST_HEAD(&ipmi_msg->head);
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ipmi_msg->device = ipmi;
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@ -225,6 +230,32 @@ static struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi)
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return ipmi_msg;
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}
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static void ipmi_msg_release(struct acpi_ipmi_msg *tx_msg)
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{
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acpi_ipmi_dev_put(tx_msg->device);
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kfree(tx_msg);
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}
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static void ipmi_msg_release_kref(struct kref *kref)
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{
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struct acpi_ipmi_msg *tx_msg =
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container_of(kref, struct acpi_ipmi_msg, kref);
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ipmi_msg_release(tx_msg);
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}
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static struct acpi_ipmi_msg *acpi_ipmi_msg_get(struct acpi_ipmi_msg *tx_msg)
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{
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kref_get(&tx_msg->kref);
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return tx_msg;
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}
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static void acpi_ipmi_msg_put(struct acpi_ipmi_msg *tx_msg)
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{
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kref_put(&tx_msg->kref, ipmi_msg_release_kref);
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}
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#define IPMI_OP_RGN_NETFN(offset) ((offset >> 8) & 0xff)
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#define IPMI_OP_RGN_CMD(offset) (offset & 0xff)
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static int acpi_format_ipmi_request(struct acpi_ipmi_msg *tx_msg,
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@ -305,7 +336,7 @@ static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
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static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
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{
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struct acpi_ipmi_msg *tx_msg, *temp;
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struct acpi_ipmi_msg *tx_msg;
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unsigned long flags;
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/*
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@ -317,18 +348,47 @@ static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
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* ipmi_recv_msg(s) are freed after invoking ipmi_destroy_user().
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*/
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spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
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list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
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while (!list_empty(&ipmi->tx_msg_list)) {
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tx_msg = list_first_entry(&ipmi->tx_msg_list,
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struct acpi_ipmi_msg,
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head);
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list_del(&tx_msg->head);
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spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
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/* wake up the sleep thread on the Tx msg */
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complete(&tx_msg->tx_complete);
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acpi_ipmi_msg_put(tx_msg);
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spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
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}
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spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
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}
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static void ipmi_cancel_tx_msg(struct acpi_ipmi_device *ipmi,
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struct acpi_ipmi_msg *msg)
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{
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struct acpi_ipmi_msg *tx_msg, *temp;
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bool msg_found = false;
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unsigned long flags;
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spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
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list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
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if (msg == tx_msg) {
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msg_found = true;
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list_del(&tx_msg->head);
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break;
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}
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}
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spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
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if (msg_found)
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acpi_ipmi_msg_put(tx_msg);
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}
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static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
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{
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struct acpi_ipmi_device *ipmi_device = user_msg_data;
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int msg_found = 0;
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struct acpi_ipmi_msg *tx_msg;
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bool msg_found = false;
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struct acpi_ipmi_msg *tx_msg, *temp;
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struct pnp_dev *pnp_dev = ipmi_device->pnp_dev;
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unsigned long flags;
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@ -339,17 +399,19 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
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goto out_msg;
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}
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spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
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list_for_each_entry(tx_msg, &ipmi_device->tx_msg_list, head) {
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list_for_each_entry_safe(tx_msg, temp, &ipmi_device->tx_msg_list, head) {
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if (msg->msgid == tx_msg->tx_msgid) {
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msg_found = 1;
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msg_found = true;
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list_del(&tx_msg->head);
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break;
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}
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}
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spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
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if (!msg_found) {
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dev_warn(&pnp_dev->dev, "Unexpected response (msg id %ld) is "
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"returned.\n", msg->msgid);
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goto out_lock;
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goto out_msg;
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}
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/* copy the response data to Rx_data buffer */
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@ -375,8 +437,7 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
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tx_msg->msg_done = ACPI_IPMI_OK;
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out_comp:
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complete(&tx_msg->tx_complete);
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out_lock:
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spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
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acpi_ipmi_msg_put(tx_msg);
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out_msg:
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ipmi_free_recv_msg(msg);
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};
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@ -491,26 +552,23 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
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if ((function & ACPI_IO_MASK) == ACPI_READ)
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return AE_TYPE;
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ipmi_device = acpi_ipmi_dev_get();
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if (!ipmi_device)
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tx_msg = ipmi_msg_alloc();
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if (!tx_msg)
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return AE_NOT_EXIST;
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tx_msg = acpi_alloc_ipmi_msg(ipmi_device);
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if (!tx_msg) {
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status = AE_NO_MEMORY;
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goto out_ref;
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}
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ipmi_device = tx_msg->device;
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if (acpi_format_ipmi_request(tx_msg, address, value) != 0) {
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status = AE_TYPE;
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goto out_msg;
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ipmi_msg_release(tx_msg);
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return AE_TYPE;
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}
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acpi_ipmi_msg_get(tx_msg);
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mutex_lock(&driver_data.ipmi_lock);
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/* Do not add a tx_msg that can not be flushed. */
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if (ipmi_device->dead) {
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status = AE_NOT_EXIST;
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mutex_unlock(&driver_data.ipmi_lock);
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goto out_msg;
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ipmi_msg_release(tx_msg);
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return AE_NOT_EXIST;
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}
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spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
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list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
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@ -523,20 +581,15 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
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NULL, 0, 0, IPMI_TIMEOUT);
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if (err) {
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status = AE_ERROR;
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goto out_list;
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goto out_msg;
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}
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wait_for_completion(&tx_msg->tx_complete);
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acpi_format_ipmi_response(tx_msg, value);
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status = AE_OK;
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out_list:
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spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
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list_del(&tx_msg->head);
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spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
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out_msg:
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kfree(tx_msg);
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out_ref:
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acpi_ipmi_dev_put(ipmi_device);
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ipmi_cancel_tx_msg(ipmi_device, tx_msg);
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acpi_ipmi_msg_put(tx_msg);
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return status;
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}
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