From 7b9844772237e34968ffd4b086d7b5ed36b30856 Mon Sep 17 00:00:00 2001 From: Lv Zheng Date: Fri, 13 Sep 2013 13:14:11 +0800 Subject: 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 Reviewed-by: Huang Ying Signed-off-by: Rafael J. Wysocki diff --git a/drivers/acpi/acpi_ipmi.c b/drivers/acpi/acpi_ipmi.c index 7ec4cd1..b9da5ef 100644 --- a/drivers/acpi/acpi_ipmi.c +++ b/drivers/acpi/acpi_ipmi.c @@ -104,6 +104,7 @@ struct acpi_ipmi_msg { 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 */ @@ -208,16 +209,20 @@ 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 *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi) +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; @@ -225,6 +230,32 @@ static struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi) return ipmi_msg; } +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, @@ -305,7 +336,7 @@ static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg, static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi) { - struct acpi_ipmi_msg *tx_msg, *temp; + struct acpi_ipmi_msg *tx_msg; unsigned long flags; /* @@ -317,18 +348,47 @@ static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi) * ipmi_recv_msg(s) are freed after invoking ipmi_destroy_user(). */ spin_lock_irqsave(&ipmi->tx_msg_lock, flags); - list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) { + 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); + /* 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; + + 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; + } } 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; + bool msg_found = false; + struct acpi_ipmi_msg *tx_msg, *temp; struct pnp_dev *pnp_dev = ipmi_device->pnp_dev; unsigned long flags; @@ -339,17 +399,19 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data) 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); - goto out_lock; + goto out_msg; } /* copy the response data to Rx_data buffer */ @@ -375,8 +437,7 @@ static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data) tx_msg->msg_done = ACPI_IPMI_OK; out_comp: complete(&tx_msg->tx_complete); -out_lock: - spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags); + acpi_ipmi_msg_put(tx_msg); out_msg: ipmi_free_recv_msg(msg); }; @@ -491,26 +552,23 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address, if ((function & ACPI_IO_MASK) == ACPI_READ) return AE_TYPE; - ipmi_device = acpi_ipmi_dev_get(); - if (!ipmi_device) + tx_msg = ipmi_msg_alloc(); + if (!tx_msg) return AE_NOT_EXIST; - tx_msg = acpi_alloc_ipmi_msg(ipmi_device); - if (!tx_msg) { - status = AE_NO_MEMORY; - goto out_ref; - } + ipmi_device = tx_msg->device; if (acpi_format_ipmi_request(tx_msg, address, value) != 0) { - status = AE_TYPE; - goto out_msg; + ipmi_msg_release(tx_msg); + return AE_TYPE; } + 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) { - status = AE_NOT_EXIST; mutex_unlock(&driver_data.ipmi_lock); - goto out_msg; + 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); @@ -523,20 +581,15 @@ acpi_ipmi_space_handler(u32 function, acpi_physical_address address, NULL, 0, 0, IPMI_TIMEOUT); if (err) { status = AE_ERROR; - goto out_list; + goto out_msg; } wait_for_completion(&tx_msg->tx_complete); acpi_format_ipmi_response(tx_msg, value); status = AE_OK; -out_list: - spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags); - list_del(&tx_msg->head); - spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags); out_msg: - kfree(tx_msg); -out_ref: - acpi_ipmi_dev_put(ipmi_device); + ipmi_cancel_tx_msg(ipmi_device, tx_msg); + acpi_ipmi_msg_put(tx_msg); return status; } -- cgit v0.10.2