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Subject[vmw_vmci RFC 05/11] Apply VMCI event code
Date
Code that manages event handlers and handles callbacks when
specific events fire.

Signed-off-by: Andrew Stiegmann (stieg) <astiegmann@vmware.com>
---
drivers/misc/vmw_vmci/vmci_event.c | 614 ++++++++++++++++++++++++++++++++++++
drivers/misc/vmw_vmci/vmci_event.h | 29 ++
2 files changed, 643 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/vmw_vmci/vmci_event.c
create mode 100644 drivers/misc/vmw_vmci/vmci_event.h
diff --git a/drivers/misc/vmw_vmci/vmci_event.c b/drivers/misc/vmw_vmci/vmci_event.c
new file mode 100644
index 0000000..7335c9e
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_event.c
@@ -0,0 +1,614 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/vmw_vmci_api.h>
+#include <linux/vmw_vmci_defs.h>
+
+#include "vmci_event.h"
+#include "vmci_driver.h"
+
+#define EVENT_MAGIC 0xEABE0000
+#define VMCI_EVENT_MAX_ATTEMPTS 10
+
+struct vmci_subscription {
+ uint32_t id;
+ int refCount;
+ bool runDelayed;
+ wait_queue_head_t destroyEvent;
+ uint32_t event;
+ VMCI_EventCB callback;
+ void *callbackData;
+ struct list_head subscriberListItem;
+};
+
+static struct list_head subscriberArray[VMCI_EVENT_MAX];
+static spinlock_t subscriberLock;
+
+struct delayed_event_info {
+ struct vmci_subscription *sub;
+ uint8_t eventPayload[sizeof(struct vmci_event_data_max)];
+};
+
+struct event_ref {
+ struct vmci_subscription *sub;
+ struct list_head listItem;
+};
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_event_init --
+ *
+ * General init code.
+ *
+ * Results:
+ * VMCI_SUCCESS on success, appropriate error code otherwise.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int __init vmci_event_init(void)
+{
+ int i;
+
+ for (i = 0; i < VMCI_EVENT_MAX; i++)
+ INIT_LIST_HEAD(&subscriberArray[i]);
+
+ spin_lock_init(&subscriberLock);
+ return VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_event_exit --
+ *
+ * General exit code.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void vmci_event_exit(void)
+{
+ int e;
+
+ /* We free all memory at exit. */
+ for (e = 0; e < VMCI_EVENT_MAX; e++) {
+ struct vmci_subscription *cur, *p2;
+ list_for_each_entry_safe(cur, p2, &subscriberArray[e],
+ subscriberListItem) {
+
+ /*
+ * We should never get here because all events should have been
+ * unregistered before we try to unload the driver module.
+ * Also, delayed callbacks could still be firing so this cleanup
+ * would not be safe.
+ * Still it is better to free the memory than not ... so we
+ * leave this code in just in case....
+ */
+ pr_warn("Unexpected free events occuring.");
+ kfree(cur);
+ }
+ }
+
+}
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * event_get --
+ *
+ * Gets a reference to the given VMCISubscription.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *-----------------------------------------------------------------------------
+ */
+
+static void event_get(struct vmci_subscription *entry) // IN
+{
+ ASSERT(entry);
+
+ entry->refCount++;
+}
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * event_release --
+ *
+ * Releases the given VMCISubscription.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * Fires the destroy event if the reference count has gone to zero.
+ *
+ *-----------------------------------------------------------------------------
+ */
+
+static void event_release(struct vmci_subscription *entry) // IN
+{
+ ASSERT(entry);
+ ASSERT(entry->refCount > 0);
+
+ entry->refCount--;
+ if (entry->refCount == 0)
+ wake_up(&entry->destroyEvent);
+}
+
+/*
+ *------------------------------------------------------------------------------
+ *
+ * event_release_cb --
+ *
+ * Callback to release the event entry reference. It is called by the
+ * VMCI_WaitOnEvent function before it blocks.
+ *
+ * Result:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *------------------------------------------------------------------------------
+ */
+
+static int event_release_cb(void *clientData) // IN
+{
+ struct vmci_subscription *sub = (struct vmci_subscription *)clientData;
+
+ ASSERT(sub);
+
+ spin_lock_bh(&subscriberLock);
+ event_release(sub);
+ spin_unlock_bh(&subscriberLock);
+
+ return 0;
+}
+
+/*
+ *-----------------------------------------------------------------------------
+ *
+ * event_find --
+ *
+ * Find entry. Assumes lock is held.
+ *
+ * Results:
+ * Entry if found, NULL if not.
+ *
+ * Side effects:
+ * Increments the VMCISubscription refcount if an entry is found.
+ *
+ *-----------------------------------------------------------------------------
+ */
+
+static struct vmci_subscription *event_find(uint32_t subID) // IN
+{
+ int e;
+
+ for (e = 0; e < VMCI_EVENT_MAX; e++) {
+ struct vmci_subscription *cur;
+ list_for_each_entry(cur, &subscriberArray[e],
+ subscriberListItem) {
+ if (cur->id == subID) {
+ event_get(cur);
+ return cur;
+ }
+ }
+ }
+ return NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * event_delayed_dispatch_cb --
+ *
+ * Calls the specified callback in a delayed context.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void event_delayed_dispatch_cb(void *data) // IN
+{
+ struct delayed_event_info *eventInfo;
+ struct vmci_subscription *sub;
+ struct vmci_event_data *ed;
+
+ eventInfo = data;
+
+ ASSERT(eventInfo);
+ ASSERT(eventInfo->sub);
+
+ sub = eventInfo->sub;
+ ed = (struct vmci_event_data *)eventInfo->eventPayload;
+
+ sub->callback(sub->id, ed, sub->callbackData);
+
+ spin_lock_bh(&subscriberLock);
+ event_release(sub);
+ spin_unlock_bh(&subscriberLock);
+
+ kfree(eventInfo);
+}
+
+/*
+ *----------------------------------------------------------------------------
+ *
+ * event_deliver --
+ *
+ * Actually delivers the events to the subscribers.
+ *
+ * Results:
+ * None.
+ *
+ * Side effects:
+ * The callback function for each subscriber is invoked.
+ *
+ *----------------------------------------------------------------------------
+ */
+
+static int event_deliver(struct vmci_event_msg *eventMsg) // IN
+{
+ int err = VMCI_SUCCESS;
+ struct vmci_subscription *cur;
+ struct list_head noDelayList;
+ struct vmci_event_data *ed;
+ struct event_ref *eventRef, *p2;
+
+ ASSERT(eventMsg);
+
+ INIT_LIST_HEAD(&noDelayList);
+
+ spin_lock_bh(&subscriberLock);
+ list_for_each_entry(cur, &subscriberArray[eventMsg->eventData.event],
+ subscriberListItem) {
+ ASSERT(cur && cur->event == eventMsg->eventData.event);
+
+ if (cur->runDelayed) {
+ struct delayed_event_info *eventInfo;
+ eventInfo = kzalloc(sizeof *eventInfo, GFP_ATOMIC);
+ if (!eventInfo) {
+ err = VMCI_ERROR_NO_MEM;
+ goto out;
+ }
+
+ event_get(cur);
+ memcpy(eventInfo->eventPayload,
+ VMCI_DG_PAYLOAD(eventMsg),
+ (size_t) eventMsg->hdr.payloadSize);
+ eventInfo->sub = cur;
+ err =
+ vmci_drv_schedule_delayed_work(event_delayed_dispatch_cb,
+ eventInfo);
+ if (err != VMCI_SUCCESS) {
+ event_release(cur);
+ kfree(eventInfo);
+ goto out;
+ }
+
+ } else {
+ struct event_ref *eventRef;
+
+ /*
+ * To avoid possible lock rank voilation when holding
+ * subscriberLock, we construct a local list of
+ * subscribers and release subscriberLock before
+ * invokes the callbacks. This is similar to delayed
+ * callbacks, but callbacks is invoked right away here.
+ */
+ if ((eventRef =
+ kzalloc(sizeof *eventRef,
+ GFP_ATOMIC)) == NULL) {
+ err = VMCI_ERROR_NO_MEM;
+ goto out;
+ }
+
+ event_get(cur);
+ eventRef->sub = cur;
+ INIT_LIST_HEAD(&eventRef->listItem);
+ list_add(&eventRef->listItem, &noDelayList);
+ }
+ }
+
+out:
+ spin_unlock_bh(&subscriberLock);
+
+ list_for_each_entry_safe(eventRef, p2, &noDelayList, listItem) {
+ struct vmci_subscription *cur = eventRef->sub;
+ uint8_t eventPayload[sizeof(struct vmci_event_data_max)] =
+ { 0 };
+
+ /* We set event data before each callback to ensure isolation. */
+ memcpy(eventPayload, VMCI_DG_PAYLOAD(eventMsg),
+ (size_t) eventMsg->hdr.payloadSize);
+ ed = (struct vmci_event_data *)eventPayload;
+ cur->callback(cur->id, ed, cur->callbackData);
+
+ spin_lock_bh(&subscriberLock);
+ event_release(cur);
+ spin_unlock_bh(&subscriberLock);
+ kfree(eventRef);
+ }
+
+ return err;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * vmci_event_dispatch --
+ *
+ * Dispatcher for the VMCI_EVENT_RECEIVE datagrams. Calls all
+ * subscribers for given event.
+ *
+ * Results:
+ * VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int vmci_event_dispatch(struct vmci_dg *msg) // IN
+{
+ struct vmci_event_msg *eventMsg = (struct vmci_event_msg *)msg;
+
+ ASSERT(msg &&
+ msg->src.context == VMCI_HYPERVISOR_CONTEXT_ID &&
+ msg->dst.resource == VMCI_EVENT_HANDLER);
+
+ if (msg->payloadSize < sizeof(uint32_t) ||
+ msg->payloadSize > sizeof(struct vmci_event_data_max))
+ return VMCI_ERROR_INVALID_ARGS;
+
+ if (!VMCI_EVENT_VALID(eventMsg->eventData.event))
+ return VMCI_ERROR_EVENT_UNKNOWN;
+
+ event_deliver(eventMsg);
+ return VMCI_SUCCESS;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * event_register_subscription --
+ *
+ * Initialize and add subscription to subscriber list.
+ *
+ * Results:
+ * VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int event_register_subscription(struct vmci_subscription *sub, // IN
+ uint32_t event, // IN
+ uint32_t flags, // IN
+ VMCI_EventCB callback, // IN
+ void *callbackData) // IN
+{
+ static uint32_t subscriptionID = 0;
+ uint32_t attempts = 0;
+ int result;
+ bool success;
+
+ ASSERT(sub);
+
+ if (!VMCI_EVENT_VALID(event) || callback == NULL) {
+ pr_devel("Failed to subscribe to event (type=%d) "
+ "(callback=%p) (data=%p).", event,
+ callback, callbackData);
+ return VMCI_ERROR_INVALID_ARGS;
+ }
+
+ sub->runDelayed = (flags & VMCI_FLAG_EVENT_DELAYED_CB) ? true : false;
+ sub->refCount = 1;
+ sub->event = event;
+ sub->callback = callback;
+ sub->callbackData = callbackData;
+ INIT_LIST_HEAD(&sub->subscriberListItem);
+
+ spin_lock_bh(&subscriberLock);
+
+ /* Creation of a new event is always allowed. */
+ for (success = false, attempts = 0;
+ success == false && attempts < VMCI_EVENT_MAX_ATTEMPTS;
+ attempts++) {
+ struct vmci_subscription *existingSub = NULL;
+
+ /*
+ * We try to get an id a couple of time before claiming we are out of
+ * resources.
+ */
+ sub->id = ++subscriptionID;
+
+ /* Test for duplicate id. */
+ existingSub = event_find(sub->id);
+ if (existingSub == NULL)
+ /* We succeeded if we didn't find a duplicate. */
+ success = true;
+ else
+ event_release(existingSub);
+ }
+
+ if (success) {
+ init_waitqueue_head(&sub->destroyEvent);
+ list_add(&sub->subscriberListItem, &subscriberArray[event]);
+ result = VMCI_SUCCESS;
+ } else {
+ result = VMCI_ERROR_NO_RESOURCES;
+ }
+
+ spin_unlock_bh(&subscriberLock);
+ return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * event_unregister_subscription --
+ *
+ * Remove subscription from subscriber list.
+ *
+ * Results:
+ * VMCISubscription when found, NULL otherwise.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static struct vmci_subscription *event_unregister_subscription(uint32_t subID) // IN
+{
+ struct vmci_subscription *s;
+
+ spin_lock_bh(&subscriberLock);
+ s = event_find(subID);
+ if (s != NULL) {
+ event_release(s);
+ list_del(&s->subscriberListItem);
+ }
+ spin_unlock_bh(&subscriberLock);
+
+ if (s != NULL)
+ vmci_drv_wait_on_event_intr(&s->destroyEvent,
+ event_release_cb, s);
+
+ return s;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * VMCIEvent_Subscribe --
+ *
+ * Subscribe to given event. The callback specified can be fired
+ * in different contexts depending on what flag is specified while
+ * registering. If flags contains VMCI_FLAG_EVENT_NONE then the
+ * callback is fired with the subscriber lock held (and BH context
+ * on the guest). If flags contain VMCI_FLAG_EVENT_DELAYED_CB then
+ * the callback is fired with no locks held in thread context.
+ * This is useful because other VMCIEvent functions can be called,
+ * but it also increases the chances that an event will be dropped.
+ *
+ * Results:
+ * VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int VMCIEvent_Subscribe(uint32_t event, // IN
+ uint32_t flags, // IN
+ VMCI_EventCB callback, // IN
+ void *callbackData, // IN
+ uint32_t * subscriptionID) // OUT
+{
+ int retval;
+ struct vmci_subscription *s = NULL;
+
+ if (subscriptionID == NULL) {
+ pr_devel("Invalid subscription (NULL).");
+ return VMCI_ERROR_INVALID_ARGS;
+ }
+
+ s = kmalloc(sizeof *s, GFP_KERNEL);
+ if (s == NULL)
+ return VMCI_ERROR_NO_MEM;
+
+ retval = event_register_subscription(s, event, flags,
+ callback, callbackData);
+ if (retval < VMCI_SUCCESS) {
+ kfree(s);
+ return retval;
+ }
+
+ *subscriptionID = s->id;
+ return retval;
+}
+
+EXPORT_SYMBOL(VMCIEvent_Subscribe);
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * VMCIEvent_Unsubscribe --
+ *
+ * Unsubscribe to given event. Removes it from list and frees it.
+ * Will return callbackData if requested by caller.
+ *
+ * Results:
+ * VMCI_SUCCESS on success, error code otherwise.
+ *
+ * Side effects:
+ * None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int VMCIEvent_Unsubscribe(uint32_t subID) // IN
+{
+ struct vmci_subscription *s;
+
+ /*
+ * Return subscription. At this point we know noone else is accessing
+ * the subscription so we can free it.
+ */
+ s = event_unregister_subscription(subID);
+ if (s == NULL)
+ return VMCI_ERROR_NOT_FOUND;
+
+ kfree(s);
+
+ return VMCI_SUCCESS;
+}
+
+EXPORT_SYMBOL(VMCIEvent_Unsubscribe);
diff --git a/drivers/misc/vmw_vmci/vmci_event.h b/drivers/misc/vmw_vmci/vmci_event.h
new file mode 100644
index 0000000..776b404
--- /dev/null
+++ b/drivers/misc/vmw_vmci/vmci_event.h
@@ -0,0 +1,29 @@
+/*
+ * VMware VMCI Driver
+ *
+ * Copyright (C) 2012 VMware, Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef __VMCI_EVENT_H__
+#define __VMCI_EVENT_H__
+
+#include <linux/vmw_vmci_api.h>
+
+int vmci_event_init(void);
+void vmci_event_exit(void);
+int vmci_event_dispatch(struct vmci_dg *msg);
+
+#endif //__VMCI_EVENT_H__
--
1.7.0.4


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