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XArray: Unify xa_cmpxchg and __xa_cmpxchg

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xa_cmpxchg() was one of the largest functions in the xarray
implementation.  By turning it into a wrapper and having the callers
take the lock (like several other functions), we save 160 bytes on a
tinyconfig build and reduce the duplication in xarray.c.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-10-31 14:39:28 -04:00
parent 4c0608f4a0
commit c5beb07e7a
2 changed files with 69 additions and 85 deletions
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113
include/linux/xarray.h
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@ -289,8 +289,6 @@ struct xarray {
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);
void *xa_cmpxchg(struct xarray *, unsigned long index,
void *old, void *entry, gfp_t);
void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
void *entry, gfp_t);
bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
@ -359,48 +357,6 @@ static inline void *xa_erase(struct xarray *xa, unsigned long index)
return xa_store(xa, index, NULL, 0);
}
/**
* xa_insert() - Store this entry in the XArray unless another entry is
* already present.
* @xa: XArray.
* @index: Index into array.
* @entry: New entry.
* @gfp: Memory allocation flags.
*
* If you would rather see the existing entry in the array, use xa_cmpxchg().
* This function is for users who don't care what the entry is, only that
* one is present.
*
* Context: Process context. Takes and releases the xa_lock.
* May sleep if the @gfp flags permit.
* Return: 0 if the store succeeded. -EEXIST if another entry was present.
* -ENOMEM if memory could not be allocated.
*/
static inline int xa_insert(struct xarray *xa, unsigned long index,
void *entry, gfp_t gfp)
{
void *curr = xa_cmpxchg(xa, index, NULL, entry, gfp);
if (!curr)
return 0;
if (xa_is_err(curr))
return xa_err(curr);
return -EEXIST;
}
/**
* xa_release() - Release a reserved entry.
* @xa: XArray.
* @index: Index of entry.
*
* After calling xa_reserve(), you can call this function to release the
* reservation. If the entry at @index has been stored to, this function
* will do nothing.
*/
static inline void xa_release(struct xarray *xa, unsigned long index)
{
xa_cmpxchg(xa, index, NULL, NULL, 0);
}
/**
* xa_for_each() - Iterate over a portion of an XArray.
* @xa: XArray.
@ -534,6 +490,61 @@ static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
return entry;
}
/**
* xa_cmpxchg() - Conditionally replace an entry in the XArray.
* @xa: XArray.
* @index: Index into array.
* @old: Old value to test against.
* @entry: New value to place in array.
* @gfp: Memory allocation flags.
*
* If the entry at @index is the same as @old, replace it with @entry.
* If the return value is equal to @old, then the exchange was successful.
*
* Context: Any context. Takes and releases the xa_lock. May sleep
* if the @gfp flags permit.
* Return: The old value at this index or xa_err() if an error happened.
*/
static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
void *old, void *entry, gfp_t gfp)
{
void *curr;
xa_lock(xa);
curr = __xa_cmpxchg(xa, index, old, entry, gfp);
xa_unlock(xa);
return curr;
}
/**
* xa_insert() - Store this entry in the XArray unless another entry is
* already present.
* @xa: XArray.
* @index: Index into array.
* @entry: New entry.
* @gfp: Memory allocation flags.
*
* If you would rather see the existing entry in the array, use xa_cmpxchg().
* This function is for users who don't care what the entry is, only that
* one is present.
*
* Context: Process context. Takes and releases the xa_lock.
* May sleep if the @gfp flags permit.
* Return: 0 if the store succeeded. -EEXIST if another entry was present.
* -ENOMEM if memory could not be allocated.
*/
static inline int xa_insert(struct xarray *xa, unsigned long index,
void *entry, gfp_t gfp)
{
void *curr = xa_cmpxchg(xa, index, NULL, entry, gfp);
if (!curr)
return 0;
if (xa_is_err(curr))
return xa_err(curr);
return -EEXIST;
}
/**
* xa_alloc() - Find somewhere to store this entry in the XArray.
* @xa: XArray.
@ -699,6 +710,20 @@ int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
return ret;
}
/**
* xa_release() - Release a reserved entry.
* @xa: XArray.
* @index: Index of entry.
*
* After calling xa_reserve(), you can call this function to release the
* reservation. If the entry at @index has been stored to, this function
* will do nothing.
*/
static inline void xa_release(struct xarray *xa, unsigned long index)
{
xa_cmpxchg(xa, index, NULL, NULL, 0);
}
/* Everything below here is the Advanced API. Proceed with caution. */
/*