Commit c5beb07e authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

XArray: Unify xa_cmpxchg and __xa_cmpxchg 



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: default avatarMatthew Wilcox <willy@infradead.org>
parent 4c0608f4

include/linux/xarray.h

+69 −44
Original line number Diff line number Diff line
@@ -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. */



/*

lib/xarray.c

+0 −41
Original line number Diff line number Diff line
@@ -1406,47 +1406,6 @@ void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) 
}

EXPORT_SYMBOL(__xa_store);



/**

 * 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: Process 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.

 */

void *xa_cmpxchg(struct xarray *xa, unsigned long index,

			void *old, void *entry, gfp_t gfp)

{

	XA_STATE(xas, xa, index);

	void *curr;



	if (WARN_ON_ONCE(xa_is_internal(entry)))

		return XA_ERROR(-EINVAL);



	do {

		xas_lock(&xas);

		curr = xas_load(&xas);

		if (curr == XA_ZERO_ENTRY)

			curr = NULL;

		if (curr == old) {

			xas_store(&xas, entry);

			if (xa_track_free(xa) && entry)

				xas_clear_mark(&xas, XA_FREE_MARK);

		}

		xas_unlock(&xas);

	} while (xas_nomem(&xas, gfp));



	return xas_result(&xas, curr);

}

EXPORT_SYMBOL(xa_cmpxchg);



/**

 * __xa_cmpxchg() - Store this entry in the XArray.

 * @xa: XArray.

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