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XArray: Handle NULL pointers differently for allocation

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For allocating XArrays, it makes sense to distinguish beteen erasing an
entry and storing NULL.  Storing NULL keeps the index allocated with a
NULL pointer associated with it while xa_erase() frees the index.  Some
existing IDR users rely on this ability.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-11-05 16:15:56 -05:00
parent 611f318637
commit d9c480435a
2 changed files with 29 additions and 12 deletions
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13
lib/xarray.c
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@ -1382,10 +1382,12 @@ void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
if (WARN_ON_ONCE(xa_is_internal(entry)))
return XA_ERROR(-EINVAL);
if (xa_track_free(xa) && !entry)
entry = XA_ZERO_ENTRY;
do {
curr = xas_store(&xas, entry);
if (xa_track_free(xa) && entry)
if (xa_track_free(xa))
xas_clear_mark(&xas, XA_FREE_MARK);
} while (__xas_nomem(&xas, gfp));
@ -1446,6 +1448,8 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
if (WARN_ON_ONCE(xa_is_internal(entry)))
return XA_ERROR(-EINVAL);
if (xa_track_free(xa) && !entry)
entry = XA_ZERO_ENTRY;
do {
curr = xas_load(&xas);
@ -1453,7 +1457,7 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
curr = NULL;
if (curr == old) {
xas_store(&xas, entry);
if (xa_track_free(xa) && entry)
if (xa_track_free(xa))
xas_clear_mark(&xas, XA_FREE_MARK);
}
} while (__xas_nomem(&xas, gfp));
@ -1487,8 +1491,11 @@ int __xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
do {
curr = xas_load(&xas);
if (!curr)
if (!curr) {
xas_store(&xas, XA_ZERO_ENTRY);
if (xa_track_free(xa))
xas_clear_mark(&xas, XA_FREE_MARK);
}
} while (__xas_nomem(&xas, gfp));
return xas_error(&xas);