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: Matthew Wilcox <willy@infradead.org>

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index c2cb042..8e59d4f 100644 (file)
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -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);
@@ -360,48 +358,6 @@ static inline void *xa_erase(struct xarray *xa, unsigned long index)
 }
 
 /**
- * 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.
  * @entry: Entry retrieved from array.
@@ -535,6 +491,61 @@ static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
 }
 
 /**
+ * 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.
  * @id: Pointer to ID.
@@ -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. */
 
 /*

diff --git a/lib/xarray.c b/lib/xarray.c
index 9cab8cf..77671d4 100644 (file)
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1407,47 +1407,6 @@ 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.
  * @index: Index into array.