#include <linux/export.h> #include <linux/generic-radix-tree.h> #include <linux/gfp.h> #include <linux/kmemleak.h> #define GENRADIX_ARY (PAGE_SIZE / sizeof(struct genradix_node *)) #define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY) struct genradix_node { union { /* Interior node: */ struct genradix_node *children[GENRADIX_ARY]; /* Leaf: */ u8 data[PAGE_SIZE]; }; }; static inline int genradix_depth_shift(unsigned depth) { return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth; } /* * Returns size (of data, in bytes) that a tree of a given depth holds: */ static inline size_t genradix_depth_size(unsigned depth) { return 1UL << genradix_depth_shift(depth); } /* depth that's needed for a genradix that can address up to ULONG_MAX: */ #define GENRADIX_MAX_DEPTH \ DIV_ROUND_UP(BITS_PER_LONG - PAGE_SHIFT, GENRADIX_ARY_SHIFT) #define GENRADIX_DEPTH_MASK \ ((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1)) static inline unsigned genradix_root_to_depth(struct genradix_root *r) { return (unsigned long) r & GENRADIX_DEPTH_MASK; } static inline struct genradix_node *genradix_root_to_node(struct genradix_root *r) { return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK); } /* * Returns pointer to the specified byte @offset within @radix, or NULL if not * allocated */ void *__genradix_ptr(struct __genradix *radix, size_t offset) { struct genradix_root *r = READ_ONCE(radix->root); struct genradix_node *n = genradix_root_to_node(r); unsigned level = genradix_root_to_depth(r); if (ilog2(offset) >= genradix_depth_shift(level)) return NULL; while (1) { if (!n) return NULL; if (!level) break; level--; n = n->children[offset >> genradix_depth_shift(level)]; offset &= genradix_depth_size(level) - 1; } return &n->data[offset]; } EXPORT_SYMBOL(__genradix_ptr); static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask) { struct genradix_node *node; node = (struct genradix_node *)__get_free_page(gfp_mask|__GFP_ZERO); /* * We're using pages (not slab allocations) directly for kernel data * structures, so we need to explicitly inform kmemleak of them in order * to avoid false positive memory leak reports. */ kmemleak_alloc(node, PAGE_SIZE, 1, gfp_mask); return node; } static inline void genradix_free_node(struct genradix_node *node) { kmemleak_free(node); free_page((unsigned long)node); } /* * Returns pointer to the specified byte @offset within @radix, allocating it if * necessary - newly allocated slots are always zeroed out: */ void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset, gfp_t gfp_mask) { struct genradix_root *v = READ_ONCE(radix->root); struct genradix_node *n, *new_node = NULL; unsigned level; /* Increase tree depth if necessary: */ while (1) { struct genradix_root *r = v, *new_root; n = genradix_root_to_node(r); level = genradix_root_to_depth(r); if (n && ilog2(offset) < genradix_depth_shift(level)) break; if (!new_node) { new_node = genradix_alloc_node(gfp_mask); if (!new_node) return NULL; } new_node->children[0] = n; new_root = ((struct genradix_root *) ((unsigned long) new_node | (n ? level + 1 : 0))); if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) { v = new_root; new_node = NULL; } } while (level--) { struct genradix_node **p = &n->children[offset >> genradix_depth_shift(level)]; offset &= genradix_depth_size(level) - 1; n = READ_ONCE(*p); if (!n) { if (!new_node) { new_node = genradix_alloc_node(gfp_mask); if (!new_node) return NULL; } if (!(n = cmpxchg_release(p, NULL, new_node))) swap(n, new_node); } } if (new_node) genradix_free_node(new_node); return &n->data[offset]; } EXPORT_SYMBOL(__genradix_ptr_alloc); void *__genradix_iter_peek(struct genradix_iter *iter, struct __genradix *radix, size_t objs_per_page) { struct genradix_root *r; struct genradix_node *n; unsigned level, i; restart: r = READ_ONCE(radix->root); if (!r) return NULL; n = genradix_root_to_node(r); level = genradix_root_to_depth(r); if (ilog2(iter->offset) >= genradix_depth_shift(level)) return NULL; while (level) { level--; i = (iter->offset >> genradix_depth_shift(level)) & (GENRADIX_ARY - 1); while (!n->children[i]) { i++; iter->offset = round_down(iter->offset + genradix_depth_size(level), genradix_depth_size(level)); iter->pos = (iter->offset >> PAGE_SHIFT) * objs_per_page; if (i == GENRADIX_ARY) goto restart; } n = n->children[i]; } return &n->data[iter->offset & (PAGE_SIZE - 1)]; } EXPORT_SYMBOL(__genradix_iter_peek); static void genradix_free_recurse(struct genradix_node *n, unsigned level) { if (level) { unsigned i; for (i = 0; i < GENRADIX_ARY; i++) if (n->children[i]) genradix_free_recurse(n->children[i], level - 1); } genradix_free_node(n); } int __genradix_prealloc(struct __genradix *radix, size_t size, gfp_t gfp_mask) { size_t offset; for (offset = 0; offset < size; offset += PAGE_SIZE) if (!__genradix_ptr_alloc(radix, offset, gfp_mask)) return -ENOMEM; return 0; } EXPORT_SYMBOL(__genradix_prealloc); void __genradix_free(struct __genradix *radix) { struct genradix_root *r = xchg(&radix->root, NULL); genradix_free_recurse(genradix_root_to_node(r), genradix_root_to_depth(r)); } EXPORT_SYMBOL(__genradix_free);