diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
commit | 57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch) | |
tree | 5e910f0e82173f4ef4f51111366a3f1299037a7b /drivers/misc/vmw_vmci/vmci_resource.c |
Initial import
Diffstat (limited to 'drivers/misc/vmw_vmci/vmci_resource.c')
-rw-r--r-- | drivers/misc/vmw_vmci/vmci_resource.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/drivers/misc/vmw_vmci/vmci_resource.c b/drivers/misc/vmw_vmci/vmci_resource.c new file mode 100644 index 000000000..9a53a30de --- /dev/null +++ b/drivers/misc/vmw_vmci/vmci_resource.c @@ -0,0 +1,227 @@ +/* + * 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; +} |