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xarray: Track free entries in an XArray

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Add the optional ability to track which entries in an XArray are free
and provide xa_alloc() to replace most of the functionality of the IDR.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-07-04 10:50:12 -04:00
parent 3d5bd6e1a0
commit 371c752dc6
4 changed files with 266 additions and 7 deletions
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101
include/linux/xarray.h
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@ -205,6 +205,7 @@ typedef unsigned __bitwise xa_mark_t;
#define XA_MARK_2 ((__force xa_mark_t)2U)
#define XA_PRESENT ((__force xa_mark_t)8U)
#define XA_MARK_MAX XA_MARK_2
#define XA_FREE_MARK XA_MARK_0
enum xa_lock_type {
XA_LOCK_IRQ = 1,
@ -217,9 +218,12 @@ enum xa_lock_type {
*/
#define XA_FLAGS_LOCK_IRQ ((__force gfp_t)XA_LOCK_IRQ)
#define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH)
#define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U)
#define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
(__force unsigned)(mark)))
#define XA_FLAGS_ALLOC (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
/**
* struct xarray - The anchor of the XArray.
* @xa_lock: Lock that protects the contents of the XArray.
@ -273,6 +277,15 @@ struct xarray {
*/
#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
/**
* DEFINE_XARRAY_ALLOC() - Define an XArray which can allocate IDs.
* @name: A string that names your XArray.
*
* This is intended for file scope definitions of allocating XArrays.
* See also DEFINE_XARRAY().
*/
#define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
void xa_init_flags(struct xarray *, gfp_t flags);
void *xa_load(struct xarray *, unsigned long index);
void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
@ -439,6 +452,7 @@ void *__xa_erase(struct xarray *, unsigned long index);
void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
void *entry, gfp_t);
int __xa_alloc(struct xarray *, u32 *id, u32 max, void *entry, gfp_t);
void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
@ -518,6 +532,93 @@ static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
return entry;
}
/**
* xa_alloc() - Find somewhere to store this entry in the XArray.
* @xa: XArray.
* @id: Pointer to ID.
* @max: Maximum ID to allocate (inclusive).
* @entry: New entry.
* @gfp: Memory allocation flags.
*
* Allocates an unused ID in the range specified by @id and @max.
* Updates the @id pointer with the index, then stores the entry at that
* index. A concurrent lookup will not see an uninitialised @id.
*
* Context: Process context. Takes and releases the xa_lock. May sleep if
* the @gfp flags permit.
* Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if
* there is no more space in the XArray.
*/
static inline int xa_alloc(struct xarray *xa, u32 *id, u32 max, void *entry,
gfp_t gfp)
{
int err;
xa_lock(xa);
err = __xa_alloc(xa, id, max, entry, gfp);
xa_unlock(xa);
return err;
}
/**
* xa_alloc_bh() - Find somewhere to store this entry in the XArray.
* @xa: XArray.
* @id: Pointer to ID.
* @max: Maximum ID to allocate (inclusive).
* @entry: New entry.
* @gfp: Memory allocation flags.
*
* Allocates an unused ID in the range specified by @id and @max.
* Updates the @id pointer with the index, then stores the entry at that
* index. A concurrent lookup will not see an uninitialised @id.
*
* Context: Process context. Takes and releases the xa_lock while
* disabling softirqs. May sleep if the @gfp flags permit.
* Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if
* there is no more space in the XArray.
*/
static inline int xa_alloc_bh(struct xarray *xa, u32 *id, u32 max, void *entry,
gfp_t gfp)
{
int err;
xa_lock_bh(xa);
err = __xa_alloc(xa, id, max, entry, gfp);
xa_unlock_bh(xa);
return err;
}
/**
* xa_alloc_irq() - Find somewhere to store this entry in the XArray.
* @xa: XArray.
* @id: Pointer to ID.
* @max: Maximum ID to allocate (inclusive).
* @entry: New entry.
* @gfp: Memory allocation flags.
*
* Allocates an unused ID in the range specified by @id and @max.
* Updates the @id pointer with the index, then stores the entry at that
* index. A concurrent lookup will not see an uninitialised @id.
*
* Context: Process context. Takes and releases the xa_lock while
* disabling interrupts. May sleep if the @gfp flags permit.
* Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if
* there is no more space in the XArray.
*/
static inline int xa_alloc_irq(struct xarray *xa, u32 *id, u32 max, void *entry,
gfp_t gfp)
{
int err;
xa_lock_irq(xa);
err = __xa_alloc(xa, id, max, entry, gfp);
xa_unlock_irq(xa);
return err;
}
/* Everything below here is the Advanced API. Proceed with caution. */
/*