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XArray: Honour reserved entries in xa_insert

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xa_insert() should treat reserved entries as occupied, not as available.
Also, it should treat requests to insert a NULL pointer as a request
to reserve the slot.  Add xa_insert_bh() and xa_insert_irq() for
completeness.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox
2019-01-02 13:57:03 -05:00
parent 76b4e52995
commit b0606fed6e
4 changed files with 126 additions and 48 deletions
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41
lib/xarray.c
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@@ -1439,6 +1439,47 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
}
EXPORT_SYMBOL(__xa_cmpxchg);
/**
* __xa_insert() - Store this entry in the XArray if no entry is present.
* @xa: XArray.
* @index: Index into array.
* @entry: New entry.
* @gfp: Memory allocation flags.
*
* Inserting a NULL entry will store a reserved entry (like xa_reserve())
* if no entry is present. Inserting will fail if a reserved entry is
* present, even though loading from this index will return NULL.
*
* Context: Any context. Expects xa_lock to be held on entry. May
* release and reacquire xa_lock if @gfp flags permit.
* Return: 0 if the store succeeded. -EEXIST if another entry was present.
* -ENOMEM if memory could not be allocated.
*/
int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
{
XA_STATE(xas, xa, index);
void *curr;
if (WARN_ON_ONCE(xa_is_advanced(entry)))
return -EINVAL;
if (!entry)
entry = XA_ZERO_ENTRY;
do {
curr = xas_load(&xas);
if (!curr) {
xas_store(&xas, entry);
if (xa_track_free(xa))
xas_clear_mark(&xas, XA_FREE_MARK);
} else {
xas_set_err(&xas, -EEXIST);
}
} while (__xas_nomem(&xas, gfp));
return xas_error(&xas);
}
EXPORT_SYMBOL(__xa_insert);
/**
* __xa_reserve() - Reserve this index in the XArray.
* @xa: XArray.