drivers/misc/vmw_vmci/vmci_resource.c

Source file repositories/reference/linux-study-clean/drivers/misc/vmw_vmci/vmci_resource.c

File Facts

System
Linux kernel
Corpus path
drivers/misc/vmw_vmci/vmci_resource.c
Extension
.c
Size
5493 bytes
Lines
223
Domain
Driver Families
Bucket
drivers/misc
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

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 ||
		     handle.context == 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,

Annotation

Implementation Notes