--- /dev/null
+/*
+ * 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.
+ */
+
+#include <linux/vmw_vmci_defs.h>
+#include <linux/hash.h>
+#include <linux/types.h>
+#include <linux/rculist.h>
+
+#include "vmci_resource.h"
+#include "vmci_driver.h"
+
+
+#define VMCI_RESOURCE_HASH_BITS 7
+#define VMCI_RESOURCE_HASH_BUCKETS (1 << VMCI_RESOURCE_HASH_BITS)
+
+struct vmci_hash_table {
+ spinlock_t lock;
+ struct hlist_head entries[VMCI_RESOURCE_HASH_BUCKETS];
+};
+
+static struct vmci_hash_table vmci_resource_table = {
+ .lock = __SPIN_LOCK_UNLOCKED(vmci_resource_table.lock),
+};
+
+static unsigned int vmci_resource_hash(struct vmci_handle handle)
+{
+ return hash_32(handle.resource, VMCI_RESOURCE_HASH_BITS);
+}
+
+/*
+ * Gets a resource (if one exists) matching given handle from the hash table.
+ */
+static struct vmci_resource *vmci_resource_lookup(struct vmci_handle handle,
+ enum vmci_resource_type type)
+{
+ struct vmci_resource *r, *resource = NULL;
+ unsigned int idx = vmci_resource_hash(handle);
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(r,
+ &vmci_resource_table.entries[idx], node) {
+ u32 cid = r->handle.context;
+ u32 rid = r->handle.resource;
+
+ if (r->type == type &&
+ rid == handle.resource &&
+ (cid == handle.context || cid == VMCI_INVALID_ID)) {
+ resource = r;
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return resource;
+}
+
+/*
+ * Find an unused resource ID and return it. The first
+ * VMCI_RESERVED_RESOURCE_ID_MAX are reserved so we start from
+ * its value + 1.
+ * Returns VMCI resource id on success, VMCI_INVALID_ID on failure.
+ */
+static u32 vmci_resource_find_id(u32 context_id,
+ enum vmci_resource_type resource_type)
+{
+ static u32 resource_id = VMCI_RESERVED_RESOURCE_ID_MAX + 1;
+ u32 old_rid = resource_id;
+ u32 current_rid;
+
+ /*
+ * Generate a unique resource ID. Keep on trying until we wrap around
+ * in the RID space.
+ */
+ do {
+ struct vmci_handle handle;
+
+ current_rid = resource_id;
+ resource_id++;
+ if (unlikely(resource_id == VMCI_INVALID_ID)) {
+ /* Skip the reserved rids. */
+ resource_id = VMCI_RESERVED_RESOURCE_ID_MAX + 1;
+ }
+
+ handle = vmci_make_handle(context_id, current_rid);
+ if (!vmci_resource_lookup(handle, resource_type))
+ return current_rid;
+ } while (resource_id != old_rid);
+
+ return VMCI_INVALID_ID;
+}
+
+
+int vmci_resource_add(struct vmci_resource *resource,
+ enum vmci_resource_type resource_type,
+ struct vmci_handle handle)
+
+{
+ unsigned int idx;
+ int result;
+
+ spin_lock(&vmci_resource_table.lock);
+
+ if (handle.resource == VMCI_INVALID_ID) {
+ handle.resource = vmci_resource_find_id(handle.context,
+ resource_type);
+ if (handle.resource == VMCI_INVALID_ID) {
+ result = VMCI_ERROR_NO_HANDLE;
+ goto out;
+ }
+ } else if (vmci_resource_lookup(handle, resource_type)) {
+ result = VMCI_ERROR_ALREADY_EXISTS;
+ goto out;
+ }
+
+ resource->handle = handle;
+ resource->type = resource_type;
+ INIT_HLIST_NODE(&resource->node);
+ kref_init(&resource->kref);
+ init_completion(&resource->done);
+
+ idx = vmci_resource_hash(resource->handle);
+ hlist_add_head_rcu(&resource->node, &vmci_resource_table.entries[idx]);
+
+ result = VMCI_SUCCESS;
+
+out:
+ spin_unlock(&vmci_resource_table.lock);
+ return result;
+}
+
+void vmci_resource_remove(struct vmci_resource *resource)
+{
+ struct vmci_handle handle = resource->handle;
+ unsigned int idx = vmci_resource_hash(handle);
+ struct vmci_resource *r;
+
+ /* Remove resource from hash table. */
+ spin_lock(&vmci_resource_table.lock);
+
+ hlist_for_each_entry(r, &vmci_resource_table.entries[idx], node) {
+ if (vmci_handle_is_equal(r->handle, resource->handle)) {
+ hlist_del_init_rcu(&r->node);
+ break;
+ }
+ }
+
+ spin_unlock(&vmci_resource_table.lock);
+ synchronize_rcu();
+
+ vmci_resource_put(resource);
+ wait_for_completion(&resource->done);
+}
+
+struct vmci_resource *
+vmci_resource_by_handle(struct vmci_handle resource_handle,
+ enum vmci_resource_type resource_type)
+{
+ struct vmci_resource *r, *resource = NULL;
+
+ rcu_read_lock();
+
+ r = vmci_resource_lookup(resource_handle, resource_type);
+ if (r &&
+ (resource_type == r->type ||
+ resource_type == VMCI_RESOURCE_TYPE_ANY)) {
+ resource = vmci_resource_get(r);
+ }
+
+ rcu_read_unlock();
+
+ return resource;
+}
+
+/*
+ * Get a reference to given resource.
+ */
+struct vmci_resource *vmci_resource_get(struct vmci_resource *resource)
+{
+ kref_get(&resource->kref);
+
+ return resource;
+}
+
+static void vmci_release_resource(struct kref *kref)
+{
+ struct vmci_resource *resource =
+ container_of(kref, struct vmci_resource, kref);
+
+ /* Verify the resource has been unlinked from hash table */
+ WARN_ON(!hlist_unhashed(&resource->node));
+
+ /* Signal that container of this resource can now be destroyed */
+ complete(&resource->done);
+}
+
+/*
+ * Resource's release function will get called if last reference.
+ * If it is the last reference, then we are sure that nobody else
+ * can increment the count again (it's gone from the resource hash
+ * table), so there's no need for locking here.
+ */
+int vmci_resource_put(struct vmci_resource *resource)
+{
+ /*
+ * We propagate the information back to caller in case it wants to know
+ * whether entry was freed.
+ */
+ return kref_put(&resource->kref, vmci_release_resource) ?
+ VMCI_SUCCESS_ENTRY_DEAD : VMCI_SUCCESS;
+}
+
+struct vmci_handle vmci_resource_handle(struct vmci_resource *resource)
+{
+ return resource->handle;
+}
Code Review / kvmfornfv.git / blobdiff