include/linux/idr.h

Source file repositories/reference/linux-study-clean/include/linux/idr.h

File Facts

System
Linux kernel
Corpus path
include/linux/idr.h
Extension
.h
Size
10430 bytes
Lines
352
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct idr {
	struct radix_tree_root	idr_rt;
	unsigned int		idr_base;
	unsigned int		idr_next;
};

/*
 * The IDR API does not expose the tagging functionality of the radix tree
 * to users.  Use tag 0 to track whether a node has free space below it.
 */
#define IDR_FREE	0

/* Set the IDR flag and the IDR_FREE tag */
#define IDR_RT_MARKER	(ROOT_IS_IDR | (__force gfp_t)			\
					(1 << (ROOT_TAG_SHIFT + IDR_FREE)))

#define IDR_INIT_BASE(name, base) {					\
	.idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER),			\
	.idr_base = (base),						\
	.idr_next = 0,							\
}

/**
 * IDR_INIT() - Initialise an IDR.
 * @name: Name of IDR.
 *
 * A freshly-initialised IDR contains no IDs.
 */
#define IDR_INIT(name)	IDR_INIT_BASE(name, 0)

/**
 * DEFINE_IDR() - Define a statically-allocated IDR.
 * @name: Name of IDR.
 *
 * An IDR defined using this macro is ready for use with no additional
 * initialisation required.  It contains no IDs.
 */
#define DEFINE_IDR(name)	struct idr name = IDR_INIT(name)

/**
 * idr_get_cursor - Return the current position of the cyclic allocator
 * @idr: idr handle
 *
 * The value returned is the value that will be next returned from
 * idr_alloc_cyclic() if it is free (otherwise the search will start from
 * this position).
 */
static inline unsigned int idr_get_cursor(const struct idr *idr)
{
	return READ_ONCE(idr->idr_next);
}

/**
 * idr_set_cursor - Set the current position of the cyclic allocator
 * @idr: idr handle
 * @val: new position
 *
 * The next call to idr_alloc_cyclic() will return @val if it is free
 * (otherwise the search will start from this position).
 */
static inline void idr_set_cursor(struct idr *idr, unsigned int val)
{
	WRITE_ONCE(idr->idr_next, val);
}

/**
 * DOC: idr sync
 * idr synchronization (stolen from radix-tree.h)
 *
 * idr_find() is able to be called locklessly, using RCU. The caller must
 * ensure calls to this function are made within rcu_read_lock() regions.
 * Other readers (lock-free or otherwise) and modifications may be running
 * concurrently.
 *
 * It is still required that the caller manage the synchronization and
 * lifetimes of the items. So if RCU lock-free lookups are used, typically
 * this would mean that the items have their own locks, or are amenable to
 * lock-free access; and that the items are freed by RCU (or only freed after
 * having been deleted from the idr tree *and* a synchronize_rcu() grace
 * period).
 */

#define idr_lock(idr)		xa_lock(&(idr)->idr_rt)
#define idr_unlock(idr)		xa_unlock(&(idr)->idr_rt)
#define idr_lock_bh(idr)	xa_lock_bh(&(idr)->idr_rt)
#define idr_unlock_bh(idr)	xa_unlock_bh(&(idr)->idr_rt)
#define idr_lock_irq(idr)	xa_lock_irq(&(idr)->idr_rt)
#define idr_unlock_irq(idr)	xa_unlock_irq(&(idr)->idr_rt)
#define idr_lock_irqsave(idr, flags) \
				xa_lock_irqsave(&(idr)->idr_rt, flags)

Annotation

Implementation Notes