diff options
| -rw-r--r-- | Documentation/core-api/xarray.rst | 4 | ||||
| -rw-r--r-- | include/linux/xarray.h | 102 | ||||
| -rw-r--r-- | lib/test_xarray.c | 53 | ||||
| -rw-r--r-- | lib/xarray.c | 50 |
4 files changed, 208 insertions, 1 deletions
diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst index e90c4925cd37..c7436da5c4ad 100644 --- a/Documentation/core-api/xarray.rst +++ b/Documentation/core-api/xarray.rst @@ -144,7 +144,9 @@ you only want to free the entry if it's ``NULL``). By default, the lowest free entry is allocated starting from 0. If you want to allocate entries starting at 1, it is more efficient to use -:c:func:`DEFINE_XARRAY_ALLOC1` or ``XA_FLAGS_ALLOC1``. +:c:func:`DEFINE_XARRAY_ALLOC1` or ``XA_FLAGS_ALLOC1``. If you want to +allocate IDs up to a maximum, then wrap back around to the lowest free +ID, you can use :c:func:`xa_alloc_cyclic`. You cannot use ``XA_MARK_0`` with an allocating XArray as this mark is used to track whether an entry is free or not. The other marks are diff --git a/include/linux/xarray.h b/include/linux/xarray.h index 883bb958e462..5ed6b462e754 100644 --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -242,6 +242,7 @@ enum xa_lock_type { #define XA_FLAGS_LOCK_BH ((__force gfp_t)XA_LOCK_BH) #define XA_FLAGS_TRACK_FREE ((__force gfp_t)4U) #define XA_FLAGS_ZERO_BUSY ((__force gfp_t)8U) +#define XA_FLAGS_ALLOC_WRAPPED ((__force gfp_t)16U) #define XA_FLAGS_MARK(mark) ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \ (__force unsigned)(mark))) @@ -499,6 +500,8 @@ void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old, int __xa_insert(struct xarray *, unsigned long index, void *entry, gfp_t); int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry, struct xa_limit, gfp_t); +int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry, + struct xa_limit, u32 *next, gfp_t); int __xa_reserve(struct xarray *, unsigned long index, gfp_t); void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t); void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t); @@ -859,6 +862,105 @@ static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id, } /** + * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray. + * @xa: XArray. + * @id: Pointer to ID. + * @entry: New entry. + * @limit: Range of allocated ID. + * @next: Pointer to next ID to allocate. + * @gfp: Memory allocation flags. + * + * Finds an empty entry in @xa between @limit.min and @limit.max, + * stores the index into the @id pointer, then stores the entry at + * that index. A concurrent lookup will not see an uninitialised @id. + * The search for an empty entry will start at @next and will wrap + * around if necessary. + * + * Context: Any context. Takes and releases the xa_lock. May sleep if + * the @gfp flags permit. + * Return: 0 if the allocation succeeded without wrapping. 1 if the + * allocation succeeded after wrapping, -ENOMEM if memory could not be + * allocated or -EBUSY if there are no free entries in @limit. + */ +static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry, + struct xa_limit limit, u32 *next, gfp_t gfp) +{ + int err; + + xa_lock(xa); + err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp); + xa_unlock(xa); + + return err; +} + +/** + * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray. + * @xa: XArray. + * @id: Pointer to ID. + * @entry: New entry. + * @limit: Range of allocated ID. + * @next: Pointer to next ID to allocate. + * @gfp: Memory allocation flags. + * + * Finds an empty entry in @xa between @limit.min and @limit.max, + * stores the index into the @id pointer, then stores the entry at + * that index. A concurrent lookup will not see an uninitialised @id. + * The search for an empty entry will start at @next and will wrap + * around if necessary. + * + * Context: Any context. Takes and releases the xa_lock while + * disabling softirqs. May sleep if the @gfp flags permit. + * Return: 0 if the allocation succeeded without wrapping. 1 if the + * allocation succeeded after wrapping, -ENOMEM if memory could not be + * allocated or -EBUSY if there are no free entries in @limit. + */ +static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry, + struct xa_limit limit, u32 *next, gfp_t gfp) +{ + int err; + + xa_lock_bh(xa); + err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp); + xa_unlock_bh(xa); + + return err; +} + +/** + * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray. + * @xa: XArray. + * @id: Pointer to ID. + * @entry: New entry. + * @limit: Range of allocated ID. + * @next: Pointer to next ID to allocate. + * @gfp: Memory allocation flags. + * + * Finds an empty entry in @xa between @limit.min and @limit.max, + * stores the index into the @id pointer, then stores the entry at + * that index. A concurrent lookup will not see an uninitialised @id. + * The search for an empty entry will start at @next and will wrap + * around if necessary. + * + * Context: Process context. Takes and releases the xa_lock while + * disabling interrupts. May sleep if the @gfp flags permit. + * Return: 0 if the allocation succeeded without wrapping. 1 if the + * allocation succeeded after wrapping, -ENOMEM if memory could not be + * allocated or -EBUSY if there are no free entries in @limit. + */ +static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry, + struct xa_limit limit, u32 *next, gfp_t gfp) +{ + int err; + + xa_lock_irq(xa); + err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp); + xa_unlock_irq(xa); + + return err; +} + +/** * xa_reserve() - Reserve this index in the XArray. * @xa: XArray. * @index: Index into array. diff --git a/lib/test_xarray.c b/lib/test_xarray.c index b5a6b981454d..eaf53f742c72 100644 --- a/lib/test_xarray.c +++ b/lib/test_xarray.c @@ -715,6 +715,57 @@ static noinline void check_xa_alloc_2(struct xarray *xa, unsigned int base) xa_destroy(xa); } +static noinline void check_xa_alloc_3(struct xarray *xa, unsigned int base) +{ + struct xa_limit limit = XA_LIMIT(1, 0x3fff); + u32 next = 0; + unsigned int i, id; + unsigned long index; + void *entry; + + XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(1), limit, + &next, GFP_KERNEL) != 0); + XA_BUG_ON(xa, id != 1); + + next = 0x3ffd; + XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(0x3ffd), limit, + &next, GFP_KERNEL) != 0); + XA_BUG_ON(xa, id != 0x3ffd); + xa_erase_index(xa, 0x3ffd); + xa_erase_index(xa, 1); + XA_BUG_ON(xa, !xa_empty(xa)); + + for (i = 0x3ffe; i < 0x4003; i++) { + if (i < 0x4000) + entry = xa_mk_index(i); + else + entry = xa_mk_index(i - 0x3fff); + XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, entry, limit, + &next, GFP_KERNEL) != (id == 1)); + XA_BUG_ON(xa, xa_mk_index(id) != entry); + } + + /* Check wrap-around is handled correctly */ + if (base != 0) + xa_erase_index(xa, base); + xa_erase_index(xa, base + 1); + next = UINT_MAX; + XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(UINT_MAX), + xa_limit_32b, &next, GFP_KERNEL) != 0); + XA_BUG_ON(xa, id != UINT_MAX); + XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(base), + xa_limit_32b, &next, GFP_KERNEL) != 1); + XA_BUG_ON(xa, id != base); + XA_BUG_ON(xa, xa_alloc_cyclic(xa, &id, xa_mk_index(base + 1), + xa_limit_32b, &next, GFP_KERNEL) != 0); + XA_BUG_ON(xa, id != base + 1); + + xa_for_each(xa, index, entry) + xa_erase_index(xa, index); + + XA_BUG_ON(xa, !xa_empty(xa)); +} + static DEFINE_XARRAY_ALLOC(xa0); static DEFINE_XARRAY_ALLOC1(xa1); @@ -724,6 +775,8 @@ static noinline void check_xa_alloc(void) check_xa_alloc_1(&xa1, 1); check_xa_alloc_2(&xa0, 0); check_xa_alloc_2(&xa1, 1); + check_xa_alloc_3(&xa0, 0); + check_xa_alloc_3(&xa1, 1); } static noinline void __check_store_iter(struct xarray *xa, unsigned long start, diff --git a/lib/xarray.c b/lib/xarray.c index c707388fb05e..89e37ac50850 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -1657,6 +1657,56 @@ int __xa_alloc(struct xarray *xa, u32 *id, void *entry, EXPORT_SYMBOL(__xa_alloc); /** + * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray. + * @xa: XArray. + * @id: Pointer to ID. + * @entry: New entry. + * @limit: Range of allocated ID. + * @next: Pointer to next ID to allocate. + * @gfp: Memory allocation flags. + * + * Finds an empty entry in @xa between @limit.min and @limit.max, + * stores the index into the @id pointer, then stores the entry at + * that index. A concurrent lookup will not see an uninitialised @id. + * The search for an empty entry will start at @next and will wrap + * around if necessary. + * + * 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 allocation succeeded without wrapping. 1 if the + * allocation succeeded after wrapping, -ENOMEM if memory could not be + * allocated or -EBUSY if there are no free entries in @limit. + */ +int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry, + struct xa_limit limit, u32 *next, gfp_t gfp) +{ + u32 min = limit.min; + int ret; + + limit.min = max(min, *next); + ret = __xa_alloc(xa, id, entry, limit, gfp); + if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) { + xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED; + ret = 1; + } + + if (ret < 0 && limit.min > min) { + limit.min = min; + ret = __xa_alloc(xa, id, entry, limit, gfp); + if (ret == 0) + ret = 1; + } + + if (ret >= 0) { + *next = *id + 1; + if (*next == 0) + xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED; + } + return ret; +} +EXPORT_SYMBOL(__xa_alloc_cyclic); + +/** * __xa_set_mark() - Set this mark on this entry while locked. * @xa: XArray. * @index: Index of entry. |