diff options
Diffstat (limited to 'lib/xarray.c')
-rw-r--r-- | lib/xarray.c | 205 |
1 files changed, 121 insertions, 84 deletions
diff --git a/lib/xarray.c b/lib/xarray.c index 5f3f9311de89..6be3acbb861f 100644 --- a/lib/xarray.c +++ b/lib/xarray.c @@ -57,6 +57,11 @@ static inline bool xa_track_free(const struct xarray *xa) return xa->xa_flags & XA_FLAGS_TRACK_FREE; } +static inline bool xa_zero_busy(const struct xarray *xa) +{ + return xa->xa_flags & XA_FLAGS_ZERO_BUSY; +} + static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark) { if (!(xa->xa_flags & XA_FLAGS_MARK(mark))) @@ -232,6 +237,8 @@ void *xas_load(struct xa_state *xas) if (xas->xa_shift > node->shift) break; entry = xas_descend(xas, node); + if (node->shift == 0) + break; } return entry; } @@ -430,6 +437,8 @@ static void xas_shrink(struct xa_state *xas) break; if (!xa_is_node(entry) && node->shift) break; + if (xa_is_zero(entry) && xa_zero_busy(xa)) + entry = NULL; xas->xa_node = XAS_BOUNDS; RCU_INIT_POINTER(xa->xa_head, entry); @@ -506,7 +515,7 @@ static void xas_free_nodes(struct xa_state *xas, struct xa_node *top) for (;;) { void *entry = xa_entry_locked(xas->xa, node, offset); - if (xa_is_node(entry)) { + if (node->shift && xa_is_node(entry)) { node = xa_to_node(entry); offset = 0; continue; @@ -604,6 +613,7 @@ static int xas_expand(struct xa_state *xas, void *head) /* * xas_create() - Create a slot to store an entry in. * @xas: XArray operation state. + * @allow_root: %true if we can store the entry in the root directly * * Most users will not need to call this function directly, as it is called * by xas_store(). It is useful for doing conditional store operations @@ -613,7 +623,7 @@ static int xas_expand(struct xa_state *xas, void *head) * If the slot was newly created, returns %NULL. If it failed to create the * slot, returns %NULL and indicates the error in @xas. */ -static void *xas_create(struct xa_state *xas) +static void *xas_create(struct xa_state *xas, bool allow_root) { struct xarray *xa = xas->xa; void *entry; @@ -625,9 +635,13 @@ static void *xas_create(struct xa_state *xas) if (xas_top(node)) { entry = xa_head_locked(xa); xas->xa_node = NULL; + if (!entry && xa_zero_busy(xa)) + entry = XA_ZERO_ENTRY; shift = xas_expand(xas, entry); if (shift < 0) return NULL; + if (!shift && !allow_root) + shift = XA_CHUNK_SHIFT; entry = xa_head_locked(xa); slot = &xa->xa_head; } else if (xas_error(xas)) { @@ -687,7 +701,7 @@ void xas_create_range(struct xa_state *xas) xas->xa_sibs = 0; for (;;) { - xas_create(xas); + xas_create(xas, true); if (xas_error(xas)) goto restore; if (xas->xa_index <= (index | XA_CHUNK_MASK)) @@ -753,10 +767,12 @@ void *xas_store(struct xa_state *xas, void *entry) void *first, *next; bool value = xa_is_value(entry); - if (entry) - first = xas_create(xas); - else + if (entry) { + bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry); + first = xas_create(xas, allow_root); + } else { first = xas_load(xas); + } if (xas_invalid(xas)) return first; @@ -786,7 +802,7 @@ void *xas_store(struct xa_state *xas, void *entry) * entry is set to NULL. */ rcu_assign_pointer(*slot, entry); - if (xa_is_node(next)) + if (xa_is_node(next) && (!node || node->shift)) xas_free_nodes(xas, xa_to_node(next)); if (!node) break; @@ -1251,35 +1267,6 @@ void *xas_find_conflict(struct xa_state *xas) EXPORT_SYMBOL_GPL(xas_find_conflict); /** - * xa_init_flags() - Initialise an empty XArray with flags. - * @xa: XArray. - * @flags: XA_FLAG values. - * - * If you need to initialise an XArray with special flags (eg you need - * to take the lock from interrupt context), use this function instead - * of xa_init(). - * - * Context: Any context. - */ -void xa_init_flags(struct xarray *xa, gfp_t flags) -{ - unsigned int lock_type; - static struct lock_class_key xa_lock_irq; - static struct lock_class_key xa_lock_bh; - - spin_lock_init(&xa->xa_lock); - xa->xa_flags = flags; - xa->xa_head = NULL; - - lock_type = xa_lock_type(xa); - if (lock_type == XA_LOCK_IRQ) - lockdep_set_class(&xa->xa_lock, &xa_lock_irq); - else if (lock_type == XA_LOCK_BH) - lockdep_set_class(&xa->xa_lock, &xa_lock_bh); -} -EXPORT_SYMBOL(xa_init_flags); - -/** * xa_load() - Load an entry from an XArray. * @xa: XArray. * @index: index into array. @@ -1308,7 +1295,6 @@ static void *xas_result(struct xa_state *xas, void *curr) { if (xa_is_zero(curr)) return NULL; - XA_NODE_BUG_ON(xas->xa_node, xa_is_internal(curr)); if (xas_error(xas)) curr = xas->xa_node; return curr; @@ -1319,13 +1305,12 @@ static void *xas_result(struct xa_state *xas, void *curr) * @xa: XArray. * @index: Index into array. * - * If the entry at this index is a multi-index entry then all indices will - * be erased, and the entry will no longer be a multi-index entry. - * This function expects the xa_lock to be held on entry. + * After this function returns, loading from @index will return %NULL. + * If the index is part of a multi-index entry, all indices will be erased + * and none of the entries will be part of a multi-index entry. * - * Context: Any context. Expects xa_lock to be held on entry. May - * release and reacquire xa_lock if @gfp flags permit. - * Return: The old entry at this index. + * Context: Any context. Expects xa_lock to be held on entry. + * Return: The entry which used to be at this index. */ void *__xa_erase(struct xarray *xa, unsigned long index) { @@ -1339,9 +1324,9 @@ EXPORT_SYMBOL(__xa_erase); * @xa: XArray. * @index: Index of entry. * - * This function is the equivalent of calling xa_store() with %NULL as - * the third argument. The XArray does not need to allocate memory, so - * the user does not need to provide GFP flags. + * After this function returns, loading from @index will return %NULL. + * If the index is part of a multi-index entry, all indices will be erased + * and none of the entries will be part of a multi-index entry. * * Context: Any context. Takes and releases the xa_lock. * Return: The entry which used to be at this index. @@ -1378,7 +1363,7 @@ void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) XA_STATE(xas, xa, index); void *curr; - if (WARN_ON_ONCE(xa_is_internal(entry))) + if (WARN_ON_ONCE(xa_is_advanced(entry))) return XA_ERROR(-EINVAL); if (xa_track_free(xa) && !entry) entry = XA_ZERO_ENTRY; @@ -1444,18 +1429,14 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index, XA_STATE(xas, xa, index); void *curr; - if (WARN_ON_ONCE(xa_is_internal(entry))) + if (WARN_ON_ONCE(xa_is_advanced(entry))) return XA_ERROR(-EINVAL); - if (xa_track_free(xa) && !entry) - entry = XA_ZERO_ENTRY; do { curr = xas_load(&xas); - if (curr == XA_ZERO_ENTRY) - curr = NULL; if (curr == old) { xas_store(&xas, entry); - if (xa_track_free(xa)) + if (xa_track_free(xa) && entry && !curr) xas_clear_mark(&xas, XA_FREE_MARK); } } while (__xas_nomem(&xas, gfp)); @@ -1465,40 +1446,45 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index, EXPORT_SYMBOL(__xa_cmpxchg); /** - * __xa_reserve() - Reserve this index in the XArray. + * __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. * - * Ensures there is somewhere to store an entry at @index in the array. - * If there is already something stored at @index, this function does - * nothing. If there was nothing there, the entry is marked as reserved. - * Loading from a reserved entry returns a %NULL pointer. - * - * If you do not use the entry that you have reserved, call xa_release() - * or xa_erase() to free any unnecessary memory. + * 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 the xa_lock to be held on entry. May - * release the lock, sleep and reacquire the lock if the @gfp flags permit. - * Return: 0 if the reservation succeeded or -ENOMEM if it failed. + * 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. -EBUSY if another entry was present. + * -ENOMEM if memory could not be allocated. */ -int __xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp) +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, XA_ZERO_ENTRY); + xas_store(&xas, entry); if (xa_track_free(xa)) xas_clear_mark(&xas, XA_FREE_MARK); + } else { + xas_set_err(&xas, -EBUSY); } } while (__xas_nomem(&xas, gfp)); return xas_error(&xas); } -EXPORT_SYMBOL(__xa_reserve); +EXPORT_SYMBOL(__xa_insert); #ifdef CONFIG_XARRAY_MULTI static void xas_set_range(struct xa_state *xas, unsigned long first, @@ -1567,7 +1553,7 @@ void *xa_store_range(struct xarray *xa, unsigned long first, if (last + 1) order = __ffs(last + 1); xas_set_order(&xas, last, order); - xas_create(&xas); + xas_create(&xas, true); if (xas_error(&xas)) goto unlock; } @@ -1591,25 +1577,25 @@ EXPORT_SYMBOL(xa_store_range); * __xa_alloc() - Find somewhere to store this entry in the XArray. * @xa: XArray. * @id: Pointer to ID. - * @max: Maximum ID to allocate (inclusive). + * @limit: Range for allocated ID. * @entry: New entry. * @gfp: Memory allocation flags. * - * Allocates an unused ID in the range specified by @id and @max. - * Updates the @id pointer with the index, then stores the entry at that - * index. A concurrent lookup will not see an uninitialised @id. + * 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. * * Context: Any context. Expects xa_lock to be held on entry. May * release and reacquire xa_lock if @gfp flags permit. - * Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if - * there is no more space in the XArray. + * Return: 0 on success, -ENOMEM if memory could not be allocated or + * -EBUSY if there are no free entries in @limit. */ -int __xa_alloc(struct xarray *xa, u32 *id, u32 max, void *entry, gfp_t gfp) +int __xa_alloc(struct xarray *xa, u32 *id, void *entry, + struct xa_limit limit, gfp_t gfp) { XA_STATE(xas, xa, 0); - int err; - if (WARN_ON_ONCE(xa_is_internal(entry))) + if (WARN_ON_ONCE(xa_is_advanced(entry))) return -EINVAL; if (WARN_ON_ONCE(!xa_track_free(xa))) return -EINVAL; @@ -1618,22 +1604,71 @@ int __xa_alloc(struct xarray *xa, u32 *id, u32 max, void *entry, gfp_t gfp) entry = XA_ZERO_ENTRY; do { - xas.xa_index = *id; - xas_find_marked(&xas, max, XA_FREE_MARK); + xas.xa_index = limit.min; + xas_find_marked(&xas, limit.max, XA_FREE_MARK); if (xas.xa_node == XAS_RESTART) - xas_set_err(&xas, -ENOSPC); + xas_set_err(&xas, -EBUSY); + else + *id = xas.xa_index; xas_store(&xas, entry); xas_clear_mark(&xas, XA_FREE_MARK); } while (__xas_nomem(&xas, gfp)); - err = xas_error(&xas); - if (!err) - *id = xas.xa_index; - return err; + return xas_error(&xas); } 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. @@ -1927,6 +1962,8 @@ void xa_destroy(struct xarray *xa) entry = xa_head_locked(xa); RCU_INIT_POINTER(xa->xa_head, NULL); xas_init_marks(&xas); + if (xa_zero_busy(xa)) + xa_mark_clear(xa, XA_FREE_MARK); /* lockdep checks we're still holding the lock in xas_free_nodes() */ if (xa_is_node(entry)) xas_free_nodes(&xas, xa_to_node(entry)); |